in this issue: - exoplanets - eso.org

Published by the EIROforum: Supported by the European Union: Part of the NUCLEUS project:

In this Issue:

Highlighting the best in science teaching and research ISSN: 1818-0353

Summer 2006 Issue 2

Exoplanets

Using insects to fight crime

Uffe Gråe Jørgensen describes thesearch for Earth-like planets aroundother stars.

Also:

Forensic entomology

titel_SiS_Issue2.RZ 05.07.2006 14:23 Uhr Seite 1

PublisherEIROforumwww.eiroforum.org

EditorDr Eleanor Hayes, European Molecular Biology Laboratory, Germany

Editorial BoardDr Giovanna Cicognani, Institut Laue Langevin, FranceDr Dominique Cornuéjols, European Synchrotron Radiation Facility, FranceDr Richard Harwood, Aiglon College, SwitzerlandRuss Hodge, European Molecular Biology Laboratory, GermanyDr Rolf Landua, European Organization for Nuclear Research (CERN), SwitzerlandDr Dean Madden, National Centre for Biotechnology Education, University of Reading, UKClaus Madsen, European Organisation for Astronomical Research in the Southern Hemisphere (ESO),GermanyDr Karl Sarnow, European Schoolnet, BelgiumDr Silke Schumacher, European Molecular Biology Laboratory, GermanyBarbara Warmbein, Deutsches Elektronen-Synchrotron (DESY), GermanyChris Warrick, European Fusion Development Agreement, UKHelen Wilson, European Space Agency, the Netherlands

Editorial AdvisorRuss Hodge, European Molecular Biology Laboratory, Germany

Copy EditorDr Caroline Hadley, European Molecular Biology Organization, Germany

CompositionNicola Graf, GermanyEmail: [email protected]

PrintersColorDruckLeimen, Germanywww.colordruck.com

Layout DesignerVienna Leigh, European Molecular Biology Laboratory, Germany

Web ArchitectFrancesco Sottile, European Molecular Biology Laboratory, Germany

Technical PartnersEuropean Schoolnetwww.eun.org

ISSNPrint version: 1818-0353Online version: 1818-0361

Cover ImagesArtist’s impression of the exoplanet OGLE-2005-BLG-390LbImage courtesy of ESOLucilia sericata (Meigen) Image courtesy of insectimages.org/Joseph Berger

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Science in School Issue 2 : Summer 2006 3

Editorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

EventsForthcoming events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7

Feature articleThe scientist of the future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10

Cutting-edge scienceAre there Earth-like planets around other stars? . . . . . . . . . . . . . . . . . . . . . . 11-16A new tree of life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-19

Teaching activitiesScientists at play: contraptions for developing science process skills . . . . . . 20-23Modelling the DNA double helix using recycled materials . . . . . . . . . . . . 24-28The chocolate challenge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-33Environmental chemistry: water testing as part of collaborative project work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34-37

Projects in science educationPromoting science and motivating students in the 21st century . . . . . . . . . 38-41The exhibition ship MS Einstein: a floating source of scientific knowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-45Linking university and school: addressing the challenges of science teaching in Italy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46-48

Science topicsForensic entomology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49-53Symmetry rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54-58Chocolate's chemical charm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59-61Epigenetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62-64

Spotlight on educationGRID: a European network of good practice in science teaching . . . . . . . . 65-67

Scientist profileA search for the origins of the brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68-71

Teacher profileA zoologist at school: my pupils and other animals . . . . . . . . . . . . . . . . . . 72-73

Science in filmVideo clip collection of European Space Agency . . . . . . . . . . . . . . . . . . . . 74-77

ReviewsPower, Sex and Suicide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78The Science Behind Medicines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Success Strategies for Women in Science . . . . . . . . . . . . . . . . . . . . . . . . . . 80The Physics of Superheroes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Real Mosquitoes Don’t Eat Meat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Learning from Patients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Resources on the webFree science journals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Back in the staffroomPutting the fizz into physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Contents

3

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www.scienceinschool.org4 Science in School Issue 2 : Summer 2006

S ince the publicationof the first issue, we

have received a lot ofenthusiastic feedbackfrom our readers. Science

teachers from across Europe particu-larly liked our innovative teachingideas, accessible science coverage,interdisciplinary topics and Europeanapproach. And these are features thatwe intend to continue to offer.

In this issue, we have contributionsfrom ten countries covering topics asvaried as astronomy, environmentalchemistry and insect biology. ExcitingEuropean projects include a floatingexhibition in Germany, an Italian uni-versity-school laboratory and a UKscheme to bring young scientists intothe classroom. Among my personalfavourites are two articles that togeth-er address the ‘theory and practice’ ofone of my favourite substances:chocolate.

Some of you have told us a little bitabout how you have used the articles

in our first issue. It seems a shamejust to tell us, though, when teacherseverywhere might be able to put yourexperience to good use. So we wouldlike to use your work to support theteaching community across Europe.Have you perhaps turned one of ourscience articles into a teachingresource? Did you adapt some of ourteaching materials to your own cur-riculum? Have you translated one ofour articles for your students? Or didyou use one in a completely differentcontext, such as a language lesson oran art class? Please tell us – we areeager to spread your ideas! We mayuse them in the journal; otherwise,you will soon have the opportunity tojoin a discussion forum on our web-site, to exchange creative ideas anduseful information.

Remember that while the print edi-tion of Science in School is in English,we are adding value to the articles we publish by offering them online in many European languages. I’mpleased to be able to report that, with

Welcome to the second issue ofScience in School

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the help of many people from acrossEurope, we already have articlesavailable in Albanian, Czech, Dutch,French, German, Italian, Portuguese,Russian, Spanish and Swedish. Ofcourse, we want to build on this, so ifyou would like to translate articles,please get in touch.

Each issue has a print run of 20,000copies, which are being sent free ofcharge to European science teachers.In this, too, we have received a greatdeal of support: teacher organisations,scientific institutes, education min-istries and others have kindly agreedto distribute print copies of Science inSchool in their own countries. If youare able to help us by distributing this free European resource further,for example, by mailing a copy with other printed material you sendto teachers, that would be a greathelp.

Finally, we are delighted to havereceived many excellent contributionsfrom readers. We hope you enjoy

reading some of them in this issue –and please continue to send usarticles!

Eleanor HayesEditor, Science in [email protected]

Editorial

www.scienceinschool.org 5Science in School Issue 2 : Summer 2006

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10 May - 30 September 2006worldwide Plus New Writers Award – bringing mathematics to lifePlus magazine is launching the PlusNew Writers Award to find peoplewho can bring mathematics to life.Published online and free of charge,Plus is an award-winning magazineabout mathematics which is aimed atthe general public. Its articles by topmathematicians and science writersprovide a window into the world ofmathematics with all its beauty andapplications, and cover fields asdiverse as art, medicine, cosmologyand sport.The competition is open to new writ-ers of any age and from any back-ground who can explain a mathemati-cal topic or application they think thepublic needs to know about. There aretwo categories of entrants: secondaryschool students and the general pub-lic. The winning entries will be readby an international audience of over100 000 in the December issue of Plus,and the prize pool includes an iPod.The closing date is 30 September 2006.More information:http://plus.maths.org/competition

15 May - 15 September 2006worldwideHave your Say: bioethics publicconsultationThe Nuffield Council on Bioethics,UK, has launched a consultation onthe ethical dilemmas related to publichealth, such as the difficulties in bal-ancing individual choice and commu-nity benefit. It is interested in theviews of young people, so pleaseencourage your students to have theirsay. A consultation paper providesbackground information and asksquestions in the context of five case

studies: infectious diseases, obesity,smoking, alcohol, and the supplemen-tation of food and water. For example:

· Are there cases where the vaccina-tion of children against the wishesof their parents could be justified?

· Would measures such as forcedquarantine, which helped to con-trol the outbreak of SARS in Asia,be acceptable in countries such asthe UK?

· What are the roles and obligationsof parents, schools, school-foodproviders and the government intackling childhood obesity?

· Should people who smoke or drinkexcessively be entitled to fewerresources from the public health-care system, or should they beasked for increased contributions?

· Fortification of foodstuffs such asflour and margarine has beenaccepted for some time. Why doesthe fluoridation of water meet withsuch resistance?

You might decide to pick one topic fora lesson – the consultation paperincludes lots of information to usewith a class. Your students’ views willcertainly be heard, as all responseswill be considered by the NuffieldCouncil. The deadline for responses is15 September 2006.More information: www.nuffieldbioethics.org

20-25 August 2006University of Amsterdam, the NetherlandsGIREP ConferenceGIREP conferences aim to bringtogether physicists, physics educatorsand physics teachers from all levels ofeducation to discuss issues in physicseducation and physics educationresearch. The biannual conferenceshave developed into major events

with over 300 participants from allcontinents except Antarctica.The theme of this year’s conference is‘modelling in physics and physicseducation’, and guides the morninglecture sessions and some workshops.The parallel paper, poster, sympo-sium, and workshop sessions mayfocus on other themes in physics edu-cation such as physics curricula, labo-ratory equipment, teacher educationand professional development, assess-ment, the use of ICT in physics educa-tion, and teaching physics for engi-neering or medicine.More information: www.girep2006.nlContact: Ton Ellermeijer ([email protected]) or Ed van denBerg ([email protected])

4-9 September 2006Braga, Portugal3rd International Conference onHands-on ScienceThe 3rd International Conference andSymposium on Hands-on Scienceoffers those involved in science edu-cation an opportunity to exchangeexperience on syllabus and policymatters, social factors and the learn-ing of science, and other issues relat-ed to science education, concentratingon the increased use of hands-onexperiments in the classroom.The contact seminar, ‘Buildingbridges: Towards an ImprovedScience Education’, will promote thediscussion and preparation of newComenius 1 and Comenius 2 schoolprojects.More information:www.hsci.info/hsci2006/index.htmlContact: [email protected]

Forthcoming events

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Events


8 September 2006Universität Kassel, GermanyEnglischsprachiger Biologie-unterricht an deutschen Schulen(English-language biology lessons inGerman schools)Biology teachers who teach in English are invited to a free workshoporganised by the Verband deutscherBiologen and the Hessian Vereinigungfür bilinguale Schulen. English-language teaching materials will be developed in small workinggroups and presented to all partici-pants. Teachers from outsideGermany are warmly welcome.More information: www.vdbiol.deContact: Matthias Bohn([email protected])

22-24 September 2006Wolfsburg, Germany‘Teaching Science in Europe’conferenceAt the conclusion of the biennialEuropean exchange process for devel-oping teaching concepts and materialsin science education, the publication‘Teaching Science in Europe’ will bepresented.More information: www.science-on-stage.deContact and registration: [email protected]

27-29 September 2006EMBL Heidelberg, GermanyELLS LearningLABThe European Learning Laboratoryfor the Life Sciences (ELLS) is an edu-cation facility to bring secondaryschool teachers into the research labfor a unique hands-on encounter withstate-of-the-art molecular biologytechniques. ELLS also gives scientistsa chance to work with teachers, help-ing to bridge the widening gapbetween research and schools.Teachers are invited to join this work-shop (theme to be arranged; theworking language will be English).More information: www.embl.de/ELLSContact: [email protected]

October 2006At-Bristol, Bristol, UKDynamic engineering course forgifted and talented youthHow do engineers design objects thatmove? How do you apply sciencefrom the natural world to solve com-plex problems? Students will designand build their own creatures usinganimation, modelling and specialistsoftware, while learning all about thedesign and engineering process ofdynamic modelling in this fun andhands-on five-day course. Get yourstudents enthused about science andengineering, while gaining invaluableskills yourself as part of your owncontinued professional development.Places are available free to groups offour students aged 12-14 and theirteachers during October half-term 2006.More information: www.at-bristol.org.ukContact: [email protected]

3-4 November 2006EMBL Heidelberg, Germany7th EMBL/EMBO Joint Conference2006: Genes, Brain/Mind andBehaviourThis conference will consider the cur-rent – and future – uses of new neuro-logical knowledge and technologies.What are the consequences when bio-chemical solutions to behavioural prob-lems such as depression, addiction, oreating disorders take precedence overattempts to repair the social environ-ment or defective interpersonal rela-tions? How do we avert the risk ofpsychopharmacology being abusedfor neurochemical enhancement?Although new knowledge coming outof the neurosciences has an enormouspotential benefit, treating or manipu-lating the mind also has importantsocial, legal and bioethical implica-tions. These are some of the mainissues that will form the basis of thisconference.More information:www.embl.de/aboutus/sciencesociety/conferences/2006/scope06.htmlContact: [email protected] [email protected]

Throughout 2006Europe-wideMarine photography competitionBy sharing the enthusiasm of scientif-ic discovery and the beauty of the sea,Marine Genomics Europe wishes toraise awareness among European citi-zens of the value of science and theneed to protect our marine heritage.In a photography competition, under-water images will be publicly exhibit-ed during 2006 in a travelling exhibi-tion at aquaria, museums and schools.Schools, science museums and othersare invited to host the exhibition.More information: www.marine-genomics-europe.orgContact: [email protected]

Date by arrangementSchullabor Novartis, Basel,SwitzerlandWorkshop ‘Gentechnik Erleben’(Experience Genetic Engineering)These workshops focus on practicallaboratory work, but backgroundinformation is given for all experi-ments. Students isolate plasmid DNAfrom bacterial cultures and digest itwith restriction enzymes. The result-ing DNA fragments are separated andvisualised by gel electrophoresis.Students should already have the nec-essary theoretical background and beover 17 years of age. The workshopsare free, conducted in German orEnglish (on request) and have amaximum of 20 participants.More information: www.schullabor.chContact: [email protected]

If you organise events or competi-tions that would be of interest toEuropean science teachers andwould like to see them mentioned inScience in School, please emaildetails, including date, location, title,abstract, website and contact emailaddress to [email protected].

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Think for a moment of all thescientific and technological

developments in recent years, andabout the prediction that new innova-tions will be introduced with increas-ing frequency: surely we should con-sider what the scientists of the futurewill need?

As developments in communicationtechnologies make information evenmore accessible, scientists are in dan-ger of drowning in a sea of irrelevantreports that range from scientific datato folklore. Future scientists will needthe skills not only to transform infor-mation into knowledge, but also toselect which information to consider.

In this century, the Internet is likelyto continue to be one of the mainsources of information for scientists.Despite the ubiquitous nature of theInternet and the general acceptancethat it is important (according to 82%of pupils and 73% of people of work-ing age), a substantial proportion of

The scientist of the future

Author, Susan Greenfield

Susan Greenfield and MartinWestwell from the Institute for theFuture of the Mind consider theneeds of the future scientist.

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Feature article


the population (30% of 9-19 year-olds)have received no lessons on using theInternet (Dutton et al., 2005). In fact,only one-third (33%) of those childrenwho are daily and weekly users havebeen taught how to judge the reliabili-ty of online information, whereas 38%trust most of the information on theInternet (Livingstone & Bober, 2005).

There seems to be a gap betweenthe information processing abilitiesand skills that will be required by thescientists of the future and the educa-tion that they receive. As the worldchanges we need to ask ourselves animportant question: what is scienceeducation for?

The first purpose of school scienceeducation should be to give the nextgeneration of citizens who choose notto continue their formal science edu-cation the means by which to under-stand science and how it works. Eachindividual should be given the toolsto appreciate how real-world scienceaffects them and how they mightform their own opinions on issues ofscience and technology. Some existingand planned courses help to meet thisneed, such as the UK’s Nuffieldw1 ASqualification (ages 16-18) in ‘Sciencefor the Public Understanding’, with afull A-level qualification (also for ages16-18 but with more detail than theAS) being considered for introductionin September 2008.

But how can we teach the way thatscience works? Think about what

happens in a class experiment todetermine the boiling point of water.One thing is certain: almost no-onewill achieve 100 °C unless theyalready know the answer and are try-ing to please the teacher. Skip will get102 °C, Tania will get 105 °C, Johnnywill get 99.5 °C, Mary will get 100.2 °C, Zonker will get 54 °C, whileBrian will not quite manage to get aresult; Smudger will boil the beakerdry and burst the thermometer. Tenminutes before the end of the experi-ment, the results are gathered: Skiphad his thermometer in a bubble ofsuperheated steam when he took hisreading; Tania had some impurities inher water; Johnny did not allow thebeaker to come fully to the boil;Mary’s result showed the effect ofslightly increased atmospheric pres-sure above sea-level; and Zonker,Brian and Smudger have not yetachieved the status of fully competentresearch scientists. At the end of thelesson, each child will be under theimpression that their experiment hasproved that water boils at exactly 100 °C, or would have done were itnot for a few local difficulties that donot affect the grown-up world of sci-ence and technology, with its fullytrained personnel and perfected appa-ratus. And yet that ten minutes rene-gotiation of what really happened isthe important part; by reflecting uponthat ten minutes, the class could learnmost of what there is to know about

how science works (Collins & Pinch,1993).

The second purpose of school sci-ence education is to reach that smallproportion of students who go on tohigher education in science and/or towork in science and technology. Forthem, building a foundation of basicknowledge and an understanding of ascientific approach is important.However, in a changing world, thisnecessary foundation will not be suf-ficient.

Modern-day and future science willincreasingly demand specialised pro-ficiency from scientists, coupled withan ability to work with other scien-tists outside their own expertise. Anatural consequence of this specialisa-tion within interdisciplinary teams isthat future scientists will have to riseto the challenge of explaining theirscience in ways that other scientistsand non-scientists can understand.Chemists will have to engage withpsychologists, molecular biologistswith nanotechnologists, and neurosci-entists with economists, until theedges between the disciplines areblurred. Even with the introduction ofnew technologies, communicationand interpersonal skills will be moreimportant than ever.

The future scientist will have to goa step further and engage with widersociety if science and technology areto maintain their place at the heart ofmodern culture. The majority of peo-

Author, Martin Westwell

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ple who did not pursue a science edu-cation will look to the minority tohelp them make decisions and formu-late opinions. However, the enthusias-tic scientist will have to take thisresponsibility seriously – it is notabout telling people what to think.

Professor Ian Diamond, the Chair ofResearch Councils UK, recently saidthat although a survey (MORI, 2005)showed that more than 80% of adultsthink science makes a good contribu-tion to society and that science willmake our lives easier, we should bedoing more to increase this number.The future scientist will be required toplay a part in ensuring that everyonein society is adequately engaged inscience. Non-scientists should feelable to contribute to scientific debateswith confidence in their opinions,whether or not they agree that sciencemakes a positive contribution to soci-ety. The integration of science withwider society and future culture iscrucial for our social as well as eco-nomic development, and this integra-tion starts at school.

In a shrinking world, science isbecoming ever more global and thisinternational community of scientistswill be pivotal if we are to seriouslyaddress worldwide problems such asclimate change and disease. Yet, inthis globalisation of science there is adanger that we are dividing intoworlds of technological ‘haves’ and‘have-nots’. Through initiatives suchas the Science Corpsw2, the scientistsof the future will be able to use theirskills and abilities to apply scienceand technology to problems in boththe developing and developedworlds.

The scientist of the future will needto be equipped to ask the right ques-tions and to find the right answers.

ReferencesCollins HM, Pinch T (1993) The Golem:

What Everyone Should Know AboutScience. Cambridge, UK:Cambridge University Press

Dutton WH, di Gennaro C, HargraveAM (2005) The Internet in Britain:The Oxford Internet Survey (OxIS).Oxford, UK: Oxford InternetInstitute. www.oii.ox.ac.uk

Livingstone S, Bober M (2005) UKChildren Go Online: Final Report ofKey Project Findings. London, UK:UK Children Go Online. www.children-go-online.net

MORI (2005) Science in Society:Findings from Qualitative andQuantitative Research. London, UK:Office of Science and Technology,Department of Trade and Industry.www.mori.com/polls/2004/ost.shtml

Web referencesw1 - The Nuffield Foundation

‘Science for Public Understanding’website: www.scpub.org

w2 - The Science Corps: www.sciencecorps.info

Baroness Greenfield CBE is Directorof the Royal Institution of GreatBritain (the first woman to hold that position) and Professor ofPharmacology at the University ofOxford, UK, where she leads a multi-disciplinary team investigating neu-rodegenerative disorders. In additionshe is Director of the Oxford Centrefor the Science of the Mind, exploringthe physical basis of consciousness,and of the Institute for the Future ofthe Mind, UK.

Her books include The Human Brain:A Guided Tour (1997), The Private Life ofthe Brain (2000), and Tomorrow’s People:How 21st Century Technology IsChanging the Way We Think and Feel(2003). She has started four compa-nies based on her research, made adiverse contribution to print andbroadcast media, and led a Govern-ment report, Women In Science. Shehas received 28 honorary degrees, anhonorary fellowship of the RoyalCollege of Physicians (2000), a non-

political life peerage (2001) as well as the Ordre National de la Legiond’Honneur (2003). In 2006 she wasinstalled as Chancellor of Heriot-WattUniversity, UK, and voted HonoraryAustralian of the Year.

Dr Martin Westwell is DeputyDirector of the Institute for the Futureof the Mind at Oxford University, UK,determining how we can harness newtechnologies to maximise the poten-tial of all individuals and safeguardtheir individuality. Martin receivedhis degree and PhD in organic chem-istry from Cambridge University andthen moved to Oxford as a researchfellow where he discovered neuro-science, the biotech industry and anumber of science and society proj-ects including the Café Scientifique.His awards as a science communica-tor include being named Scientist ofthe New Century in 1999 by TheTimes/Novartis .


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There are 100 billion stars in ourgalaxy, the Milky Way. Many of

them are quite similar to our star, theSun. Does that mean that there aremillions or billions of planets likeEarth in our galaxy? Maybe evenplanets with life like us? Until recent-ly, astronomers had only been able tospot planets quite unlike those in ourown Solar System, but in August 2005our group discovered the first planet

outside our Solar System which mighthave formed and developed in thesame way as Earth.

Scientists believe that our own SolarSystem formed from a big interstellarcloud that collapsed 4.6 billion yearsago. Most of the cloud became theSun, but because the cloud was rotat-ing, a small fraction of it was forcedinto a flat disk of gas and dust aroundthe newborn Sun. In the outer part of

the disk, far away from the Sun andbeyond the present-day orbit ofJupiter, it was cold enough for waterto form ice crystals and snowflakes.Just like on a cold winter day, it wassnowing out there – but it snowed formillions of years. Colliding snow-flakes and dust grains slowly becamelarger clumps of solid material, a bitlike dirty snowballs. Once the firstclump grew larger than 15 times the

Are there Earth-like planetsaround other stars?

Uffe Gråe Jørgensenfrom the Universityof Copenhagen,Denmark, describesthe search for Earth-like planetselsewhere in ourgalaxy.

Imag

e co

urte

sy o

f ESO

The ESO observatory at La Silla, Chile

Cutting-edge science

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mass of Earth, its gravity dragged inthe surrounding gas. In this way, theclump transformed itself into a gigan-tic planet with a solid core surround-ed by huge amounts of compressedgas – we call it a gas planet, eventhough it also has a solid core of icewith small amounts of stone andmetal inside. Jupiter, which is thelargest gas planet in our Solar System,contains 300 times more mass thanEarth, mainly in the form of com-pressed hydrogen and helium gas.

In the inner part of the disk, nearerthe Sun, however, it was too warm forwater to form snow. Instead, waterstayed in the cloud, just like it stays inthe air on a warm summer day. Onlythe very rare dust particles made ofstone and metal could form solidclumps, and therefore the inner plan-ets, Mercury, Venus, Earth, and Mars,became ‘small’ stone clumps (with aniron core), just like the rocky sur-roundings of Earth with which we arefamiliar. The lack of snow in the innerpart of the cloud prevented the plan-ets in this region from ever becominghuge gas planets like Jupiter. Thesmall amount of water and atmos-phere we have today came later toEarth (in a very complicated way,which is still a subject of intensedebate between scientists), but it isnext to nothing compared with thehuge gas masses of Jupiter and theother gas planets.

It was therefore a big surprise whenthe first planet discovered aroundanother star, in 1995, was a giganticgas planet in a tiny orbit. At firstglance, the discovery of this planet, 51Pegasi b, strongly conflicted with ourunderstanding of how planetary sys-tems should form, as we had learnedfrom studying our own Solar System:large gas planets in large orbits andsmall, Earth-like, solid planets insmaller orbits. However, the methodthat had been used to find planets(see below) was sensitive to such‘strange’ planets. Today, it is generallybelieved that these large gas planets

A comparison of the orbits of Mercury, Venus, and Earth with the orbit of 51Pegasi b, the first discovered exoplanet

Our Solar System

New Solar System51 Pegasi

Venus

EarthMercury

Comparison of planets

Mercury Earth Jupiter Saturn 51 Pegasi b

Mass 0.06 1.00 317.8 95.2 148.8Diameter 0.38 1.00 11.2 9.5 ca. 10Density (water=1) 5.4 5.5 1.3 0.7 ca. 1Distance from star 0.39 1.00 5.20 9.54 0.52Orbital period 88 days 1year 11.9 years 29.5 years 4.2 daysDay temperature (°C) 350 15 -150 -180 1000Composition iron rock H and He H and He H and He

rock iron gas gas gas

Comparison of the Sun and 51 Pegasi

Sun 51 Pegasi

Radius 1.0 1.4Mass 1.0 0.95Temperature (°C) 5500 5430Age 4.6 billion years 8 billion yearsMetallicity 1.0 1.2 to 1.5Spectral type G2 (main sequence) G3 (main sequence)Luminosity 1.0 1.8

New planet (51 Pegasi b)

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formed in the same way as didJupiter and Saturn, but then slowlydrifted inwards, towards the star theyorbit. If Jupiter had behaved like thatin our Solar System, it would mostlikely have engulfed our small Earthinto its huge interior while passingus, and there would be no Earthtoday. But the orbits of all the planetsin our Solar System are remarkablystable. We do not know if this stabili-ty is normal for planetary systems, orif it is unique to our Solar System.

Without it, conditions in our systemwould most likely have changed toodrastically and too often for our frag-ile life to have survived. For example,the stability of the outer planetscaused more than a thousand billioncomets to be removed from the innerSolar System shortly after Earth wasformed. If they had still been aroundtoday, regular collisions with themwould most likely have removed our atmosphere and evaporated theoceans, preventing life from gaining

a foothold. Maybe we exist in ourSolar System precisely because it isthe only place in the Universe thatallows life to survive and developover biological time-scales (i.e. bil-lions of years).

If a planet orbits a star other thanthe Sun, we call it an extrasolar plan-et, or an exoplanet. Since 1995, scien-tists have discovered almost 200 exo-planets. Most of them (including thefirst) have been discovered using theradial velocity technique, which looks


Recent developments on exoplanets at ESO

The discovery at La Silla of an exoplanet of five timesthe mass of Earth is the latest achievement in a longseries of breakthroughs made with ESO’s telescopes.The ESO La Silla Paranal Observatory, with its largeinstruments equipping the Very Large Telescope(Pierce-Price, 2006) and the various smaller tele-scopes, is very well equipped for the study of exoplan-ets, with instruments for adaptive optics imaging, highresolution spectroscopy and long-term monitoring. Alist of the most recent of these achievements is givenbelow.

2002: Discovery of a dusty and opaque disc in whichplanets are forming or will soon form, surrounding ayoung solar-type star. This disc is similar to the one inwhich astronomers think the Earth and other planets inthe Solar System formed. For more details, seewww.eso.org/outreach/press-rel/pr-2002/pr-09-02.html

2004: Confirmation of the existence of a new class ofgiant planet. These planets are extremely close to theirhost stars, orbiting them in less than two Earth days,and are therefore very hot and ‘bloated’. For moredetails, see www.eso.org/outreach/press-rel/pr-2004/pr-11-04.html

2004: Discovery of the first possible rocky exoplanet,an object 14 times the mass of Earth . For more details,see www.eso.org/outreach/press-rel/pr-2004/pr-22-04.html

2004: First image achieved of an exoplanet, leadingthe way for a more direct study of exoplanets. For moredetails, see www.eso.org/outreach/press-rel/pr-2004/

pr-23-04.html and www.eso.org/outreach/press-rel/pr-2005/pr-12-05.html

2004: Ingredients for the formation of rocky planetsdiscovered in the innermost regions of the proto-plan-etary discs around three young stars. This suggests thatthe formation of Earth-like planets may not be sounusual. For more details, see www.eso.org/outreach/press-rel/pr-2004/pr-27-04.html

2005: Discovery of a planet of mass comparable toNeptune around a low-mass star, the most commontype of star in our Galaxy. For more details, seewww.eso.org/outreach/press-rel/pr-2005/pr-30-05.html

2006: Discovery of the smallest known exoplanet, withonly five times the mass of Earth (this paper). For moredetails, see www.eso.org/outreach/press-rel/pr-2006/pr-03-06.html

2006: Detection of three Neptune-like planets, each ofmass between ten and 20 times that of Earth, around astar that also possesses an asteroid belt. Of all knownsystems, this is the most similar to our own SolarSystem. For more details, see www.eso.org/outreach/press-rel/pr-2006/pr-18-06.html

2006: Observations show that some objects with sev-eral times the mass of Jupiter have a disc surroundingthem and may form in a similar way to stars. It thusbecomes much more difficult to define precisely whata planet is. For more details, see www.eso.org/outreach/press-rel/pr-2006/pr-19-06.html

Henri Boffin, ESO

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for changes in the position of spectrallines from the star and is most sensi-tive to very big planets in very smallorbits. Most of the many other tech-niques that are now used to search forextrasolar planets are also mainly sen-sitive to planets that are very differentfrom the planets in our Solar System.Therefore we continue to find mainly‘unexpected’ planets. We find largegas planets in small orbits where theycannot have formed, or small solidplanets in ultra-small orbits wherethey cannot have formed, or extreme-ly large and bright planets in extreme-ly large orbits around very smallstars, and so forth. But this does notnecessarily mean that even Earth-likeplanets are rare in the Universe. Wejust need to look for them with othermethods. The main difficulty indetecting Earth-like exoplanetsaround distant stars is that Earth issmall (so its light is obscured by thelight of the star it orbits) and at thesame time in a relatively large orbit(so its star must be observed for avery long time before any periodicmovement can be detected).

For some years, our group has beenworking on the implementation of amethod called microlensing (see fig-ure on page 16), which is particularlysensitive to planets in orbits resem-bling that of Earth, and those withmasses as small as that of Earth.When one star passes almost directlyin front of another, its gravitationalfield will bend the light from thebackground star. The front star willthen act as a magnifying lens, becauseit causes the light from the back-ground star to reach us from severaldirections at the same time, therebymaking it appear brighter. If the frontstar is alone (i.e. there is no planetmoving around it), its gravitationalfield will be symmetric, and thebrightness of the background star willtherefore first increase, as the starsapproach one another, and thendecrease, as the two stars slide awayfrom one another again. In this case,

the light curve is symmetric in time.If, on the other hand, the front star isorbited by a planet, the gravitationalfield will be asymmetric. The bright-ness of the background star will thendecrease in a way different to how itincreased: the light curve will beasymmetric. It is these asymmetriesthat we look for. Typically the frontstar will be a star somewhat smallerthan the Sun (there are simply moreof these in our galaxy) and the back-ground star will be a cool, red giantstar (easiest to spot because they arevery bright).

At Las Campanas observatory inChile, a Polish team called OGLEw1

monitors about 100 million stars, andalerts the scientific community whenany of them become microlensed. In acollaboration between telescopes atthe European Organisation forAstronomical Research in theSouthern Hemisphere (ESO) inAustralia and South Africa, we haveformed the PLANETw2 group, whichmonitors the best of the OGLE alerts24 hours a day. During the most criti-cal stages, we observe a given starevery few minutes. In this way, wehave resolved the light curves of morethan 200 microlensing events duringthe last three years. From the manylight curves that did not show anyplanetary signs, we conclude thatJupiter-Saturn-like planets (i.e. largegas planets) in Jupiter-Saturn-likeorbits (i.e. large orbits) are rare in ourgalaxy. In other words, the kinds ofplanets that stabilised our own SolarSystem over biological time-scalesseem to be uncommon in the Uni-verse – a central conclusion for esti-mating the odds of finding life likeours elsewhere in the galaxy.

On 9 August 2005, however, theDanish telescope at the ESO observa-tory at La Silla, Chile, spotted the firstsigns of the kind of light-curve asym-metry we had been looking for, sug-gesting the presence of an orbitingplanet. We immediately notified ourcollaborators, both inside and outside

our team, and over the next six hours,four telescopes in Chile, New Zealandand Australia confirmed the nature ofthe deviation. After three months ofintensive modelling of the light curve,we were finally convinced that we hadseen the signal from the smallest exo-planet that was ever observed, and inJanuary 2006, we announced the dis-B

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covery in Nature (Beaulieu et al., 2006).The new planet has the name

OGLE-2005-BLG-390Lb, or, in short,OB05390. It is five times the mass ofEarth (i.e. it is more ‘Earth-like’ thanMars, which is one-tenth Earth’smass), and circles a star 22 000 light-years away, in an orbit three times thesize of Earth’s orbit. This makes it the

only known exoplanet which, accord-ing to theories, is made of solid rock,like Earth, and orbits its star at a dis-tance at which it could also haveformed. It may be the first extrasolarsystem ever seen in which the planetsare in stable orbits, and where condi-tions for life are stable over biologicaltime-scales, as in our own Solar System.


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This article providesup-to-date informa-tion on develop-ments in the field ofextrasolar planet dis-covery. It details thediscovery of a newEarth-like planetorbiting a star 22 000light-years awayusing a new tech-nique called micro-lensing – the detec-tion of asymmetry inthe gravitational lens-ing of light from adistant star as it pass-es behind a closerstar – instead of theusual search for a‘wobble’ in a star’sspectral lines.

The article is of inter-est mainly to thosestudying or teachingastronomy or relativi-ty (as an applicationof Einstein’s ideas ofgravitational lensing)to update their sub-ject knowledge or forgeneral-interest read-ing. The article itselfcontains no pedagog-ical content. Theclear language andinteresting subject,however, mean that itcould be used withc o m p r e h e n s i o nquestions even forlower age groups(e.g. 15-16 year-olds). The articlecould also be usedwith more advancedstudents as the begin-ning of a researchtopic.

Mark Robertson, UKRE

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ReferencesBeaulieu JP et al. (2006) Discovery of

a cool planet of 5.5 Earth massesthrough gravitational microlens-ing, Nature 439: 437-440. doi:10.1038/nature04441

Pierce-Price D (2006) Running one ofthe world’s largest telescopes,Science in School 1 56-60.www.scienceinschool.org/2006/issue1/telescope/

Web referencesw1 - OGLE:

www.astrouw.edu.pl/~oglew2 - PLANET: http://planet.iap.fr

ResourcesCalifornia & Carnegie Planet Search, a

regularly updated site with impor-tant information about exoplanets:http://exoplanets.org

The Extrasolar Planets Encyclopaedia:http://exoplanet.eu

A recent in-depth and technicalreview of the subject: Marcy G etal. (2005) Observed properties ofexoplanets: masses, orbits, andmetallicities. Progress of TheoreticalPhysics Supplement 158: 24-42.http://ptp.ipap.jp/link?PTPS/158/24

Further information about theresearch of Uffe Gråe Jørgensen andhis colleagues is available here:www.nbi.ku.dk/side22730.htm

Uffe Gråe Jørgensen is AssociateProfessor at the Niels Bohr Institute,University of Copenhagen, Denmark

Explanation of microlensing

Image courtesy of K

night Ridder / Tribune Inform

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In the margins of one of CharlesDarwin’s notebooks is a small, twig-

like drawing – unimpressive until yourealise that it represents an enormousintellectual leap, a milestone in humanhistory. It is the first modern sketch of atree of life, representing the fact that dis-tinct species had common ancestors. Fora century, naturalists had collected factsabout species, naming them and group-ing them according to their similarities.Darwin suddenly understood that thesimilarities represented familial relation-ships.

Two decades later, another tree wasmeticulously composed by ErnstHaeckel, the great German naturalistand embryologist and a fanatical admir-er of Darwin. Haeckel’s chart attempts to synthesize the plant and animal king-doms into a single genealogical record oflife on Earth. He got a lot of things right,but the tree goes back only so far. Once it reached one-celled organisms, he wasstuck – scientists were only beginning to glimpse the amazing variety of suchspecies alive on Earth; they certainlydidn’t know enough to make a convinc-ing phylogeny stretching back before the divergence of plants and animals.

Since then, scientists have filled inbranches and twigs, climbed down thetrunk, and pushed deeply into the roots,

At the European Molecular BiologyLaboratory in Heidelberg, Germany, PeerBork’s research group has meticulouslyreconstructed a new tree of life – tracingthe course of evolution. Russ Hodgeexplains.

A new tree of life


Science in School Issue 2 : Summer 2006

From the top: Tobias Doerks,Christian von Mering, Peer Bork and

Christopher Creevey

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drawing on the written record of evo-lution that is preserved in DNA. Still,questions remain, particularly withregard to the early history of life onEarth. Peer Bork’s group at theEuropean Molecular BiologyLaboratory in Heidelberg, Germany,has now finished the highest-resolu-tion tree of evolution that has yetbeen made. It may never be final –millions of species surely remain to befound, and those we know will con-tinue to evolve. But it fills in many ofthe gaps, and will help scientists sortout fragmentary clues of the existenceof new organisms. It also sheds lighton the very early history of life onEarth.

Early in Earth’s history, there exist-ed an organism that would give riseto all the species known today. In1994, Christos Ouzounis and NikosKyrpides gave this shadowy creaturea name: LUCA, for the last universalcommon ancestor. Studies of DNAsequences taken from plants, fungi,animals, bacteria, and another form ofone-celled organism called Archaeaproved that it must have existed. Butuntil recently, scientists could sayvery little else about it.

“Two things have changed,” Peersays. “First is the immense amount ofinformation we have from DNAsequencing – over 350 organismshave been completely sequenced,spread across the entire spectrum oflife. This gives us a huge amount ofdata that can be compared to make agood tree and also to answer somequestions about LUCA. Certain keygenes can be found in all of them, andthe chemical ‘spelling’ of these genespermits us to group them into fami-lies and historical relationships.”

It also allows researchers to recon-struct hypothetical ancestors. A fun-damental principle of evolution,called the principle of commondescent, states that if two organismsshare features, it is almost always

because they inherited the characteris-tics from a common ancestor. So bycomparing existing species, scientistscan obtain a picture of more ancientforms of life.

“Over the past few decades, scien-tists have realised there is an impor-tant exception to this rule,” Peer says.“Bacteria can swap genes with eachother, and sometimes they can evensteal a gene from a plant or an ani-mal. Once that has happened, theypass the gene on to their descendents.Such genes have a completely differ-ent profile to genes inherited the nor-mal way. It’s like finding a branchfrom a tree that grows crosswise andfuses into another branch.”

Peer says that attempts have beenmade to find such genes and elimi-nate them when building trees fromDNA sequence data. But no one knewhow often such events, called hori-zontal gene transfer (HGT), hap-

pened, or had developed a convincingmethod for finding them. “For awhile, it was almost as if the amountof data was increasing the problemrather than solving it,” Peer says.“There were big debates, and thenumbers of classifications were grow-ing rather than reaching a consensus.”Part of the problem lay in the fact thatthe work could only be done by com-puter in a highly automated way, dueto the incredible amount of genomicdata that had to be sifted through.

Francesca Ciccarelli, a postdoc inPeer’s group, decided to tackle theproblem of the tree anew and find asolution to the problem of the HGTs.She started by combing the completegenomes of 191 species for uniqueorthologues – genes in differentspecies that had evolved from a com-mon ancestral gene. The task was dif-ficult because it couldn’t be complete-ly automated. Francesca found 36

The new tree of life includes all three domains of life: Archaea, Bacteria andEukaryota. There are so many species that the tree has to be drawn in a circle

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cases, five of which seemed to havebeen shuffled around through HGTsand were thus discarded.

Eliminating these from the analysis,the scientists could now build a com-plete tree by combining informationfrom 31 genes. Peer was worried thatsome HGTs might have still haveslipped in – a single mistake couldspoil the quality of the tree. So the sci-entists put the computer to workdoing some heavy lifting. The 31genes were randomly divided intofour groups. Trees were systematical-ly drawn over and over again, for allof the genes in each group, with theexception of a single gene that waseliminated in each round. Then theresults were compared. If the branch-es of the trees changed from pass topass, an HGT was likely to beinvolved, and the gene was submittedto two more tests. In the end, the sci-entists found seven more candidates

for HGTs, which they elimi-nated from their analysis.

The remaining informa-tion was combined into asuper-tree which was com-pared once again to treesbased on individual genes inthree different ways. “Anyone of these methods on itsown might have left a treewith some mistakes,” Peersays, “but by combiningthem, we’re confident thatwe have an extremely accu-rate picture of the evolution-ary history of these mole-cules and the species.”

The results clear up someold controversies, for exam-ple, a debate about the veryearly evolution of animals.Some trees in the past pro-posed that the vertebrates(which include humans)split off from another branchwhich would remain unitedfor a while before splittinginto separate branches lead-ing to worms and insects.

The new version groups things differ-ently: vertebrate and insect ancestorssplit off from the worms together, anddiverge from each other later.

The higher resolution of the tree isalso important, Peer says, because ofmetagenomic studies which areunderway to sequence all the genesfound in environments such as farmsoil or ocean water. His group hasparticipated in several such projects.“Most sequencing approaches startwith a given organism and workthrough its whole genome systemati-cally,” he says. “Metagenomics issequencing a place – like a globalpositioning system coordinate. Inmany cases we recover fragmentarytraces of thousands of genes, andhave no idea what organism theycome from. Often these moleculesrepresent creatures that have neverbeen seen before.” The breadth anddetail of the new tree will allow scien-

tists to make much better guessesabout where such fragments fit in and what types of living beings theybelong to.

Has the living world been fairlysplit up into major branches, limbs,and twigs, or have we overempha-sized the prominence of our ownlineage? A close look at the new treeshows that the latter seems to be thecase. The eukaryotes, which includeyeast, plants and animals such as our-selves, are so visibly different fromone another that scientists havepushed them apart from each otheron the tree. Genetically speaking,however, the species are often muchmore closely related than manysingle-celled forms of life.

“Smaller genomes evolve faster,”Peer says. “There isn’t a single organ-ism that has been sequenced that isboth evolving fast and has a largegenome. It suggests that some of thesimplest species around have endedup that way because they havepruned things down. Evolution isn’talways about acquiring complexity.”

The study also gives the scientists acloser look at LUCA. “One very bigquestion has been what the earliestbacteria were like when they split off from the Archaea. Bacteria aregrouped into two classes, calledGram-positive and Gram-negative,based on features of their membranes.The new tree reveals that Gram-posi-tive bacteria evolved first. And if youlook at their repertoire of genes, theyseem to be suited to a very hot envi-ronment. The first Archaea were dis-covered in hot ocean vents, and mostof the species alive today are ther-mophilic. It strongly suggests thatLUCA was, too.”

This article appears in the annualreport of the European Molecular BiologyLaboratory, a collection of articles ontopics from the most current science. The rest of the report can be seen at:www.embl.org/aboutus/news/publications/report.html

Haeckel’s tree of life, from The Evolution of Man(1879)


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To recap, science process skills arefundamental to science, allowing

everyone to conduct investigationsand reach conclusions. We are con-vinced that there is a serious educa-tional gap in this area, both in bring-ing these skills into the classroom and in training teachers to do this. To facilitate the introduction of sci-ence-inquiry principles in school, wedeveloped a set of lab activities foruse in primary and secondaryschools. In the first of two articles (Tifi et al., 2006), we discussed thedevelopment of these activities anddescribed games involving ‘trans-former machines’. Below, we describecontraptions – physical black boxes to inspire exploration, hypothesis and testing.

ContraptionsThe principle behind contraptions

is similar to that of the operatingmachines described in our first article,

but these are physical black-boxmachines that have at least twoexternal movable parts that act asinput and output. The parts may becoloured threads, rotating knobs orstems, penetrating bars or tiltinglevers. The two are coupled throughan inner mechanism of gears, pulleysand belts, wheels or Technic Lego®.Alternatively, common objects may be

used, such as the rollers found incorrector pens.

The students explore the contrap-tions and do experiments, manipulat-ing one of the external parts (input)and observing causal behaviour(output) on other external parts.

The students can only infer theinner mechanism by developingmodels and comparing the predic-tions from the models with whathappens with the actual machine.

Gear and pulley machines can havetwo or more wheels of the same ordifferent diameters. They can becoupled using a single thread, or acontinuous belt, creating a wideassortment of hidden mechanisms.

In the second of two articles on developingthe processes of enquiry, hypothesis and test-ing, Alfredo Tifi, Natale Natale and AntoniettaLombardi describe how to build and applysome of the low-cost equipment they havedeveloped.

Scientists at play:contraptions for developingscience process skills

Lego gear wheels

Corrector pen roller

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Science in School Issue 2 : Summer 2006www.scienceinschool.org 21

See page 23 for a construction plan ofthe tape contraption.

With a simple reelwound with twocoloured threads inopposite directions,all hidden inside acard box, you canmake a machine inwhich pulling a redthread causes awhite thread on theopposite side to bedrawn inside. If the threads arewound in opposite directions on twocoaxial bobbins of very different

diameters, pulling both threads caus-es the box itself to move vertically,

whereas pullingjust one threadcauses the otherthread to bedrawn into thebox at a differentrate. See page 22for a constructionplan of the thread-lifting contraption.

These investiga-tions were the most popular amonggrade 4-5 children (ages 10-12): ideaswithin ‘research groups’ (3-4 pupils)

were discussed and the childrenenthusiastically searched for effectivemodels, using ribbons, wheels, pencil-made axis, and paper stripsw1.

Not only did the students closelyobserve the machine behaviour andrecord the factual evidence, as well asconjecturing, improving, debating anddefending their models; they also had astrong creative need to make their ownprototypes of the models. One groupused the principle of the threadmachine to build pretty gadgets fortheir mothers, in which different wordsof affection were displayed on thesame fabric band, depending on theside from which the band was pulled.

The manipulative aspect of thesetangible machines encourages repre-sentative and kinaesthetic thinking,both of which are crucial for scientificinsight and speculation. Furthermore,the children feel comfortable withthese investigations, because they areat the same level, tackling a complete-ly new job with classmates of equalabilities. This is in sharp contrast tothe low self-esteem that children oftenhave in content-based curricular sub-jects. It is not uncommon to find chil-dren who cope successfully and par-ticipate actively in these modellingand creative activities, despite lowscores in traditional schoolwork.

Investigating gears

Modelling gears

A gadget for mother

Teaching activities

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Materials· Cardboard box

· Two 50-70 cm pieces of strong,coloured thread

· Two pieces of compact foam poly-styrene cut to fit the opposite wallsof the box, both with a hole in thecentre

· A plastic tube (e.g. from a pen) andan axis to be inserted inside theplastic tube (this latter is as long asthe opposite sides of the box andpermits the external tube to slideand to rotate freely; the tube isshorter then the internal axis sothat it is free to rotate once it ismounted in the box)

· A spool that can be fixed on thetube with the larger diameter

· One or two discs adaptable to therotating tube, to control therolling-up of the thread

· Two nuts.

Method1. Open a paperclip and heat it over

a flame; use this hot point to makea hole in the plastic spool whereyou want to fix the thread andwhere the thread will be rolled up.Pass the thread through this holeand fix it with a big knot.

2. Attach another piece of thread,tying it tightly near the centre ofthe tube.

3. Insert the spool almost onto thecentre of the tube, and then fix the

knot with a drop of quick-dryingglue (above centre). The twothreads must be rolled up as far aspossible near the centre of thetube.

4. Insert the counter-disc on theopposite side of the big spool (thisis optional). If the spool groove isnot deep enough, use another discto separate the two threads andprevent them from tangling. Fix allpieces over the tube with quick-drying glue.

5. Cut 50-70 cm of each thread; maketwo narrow holes at the centre oftwo opposite sides of the box at aright angle to the rotating axisdirection, then pass the threadsthrough the two holes. Only onethread must be completely rolledaround its seat. Tie two nuts to thefree end of the threads.

6. Insert the axis inside the tube andmount the rotating axis over thetwo facing styrofoam rectangles,standing outside of the box.

7. Insert the mechanism into the box,pulling out the threads to leavethem free to go out and in. Closethe box and seal it only when youare sure it works well; then give itto the children!

OperatingWhen both threads are pulled, the

box moves upwards and towards thethread that is rolled around the small-

er pulley. Relaxing the pulling forceallows the box to drop under gravity.The rates of disappearance and emer-gence of the two threads are propor-tional to the diameter of the pulley towhich they are fixed.

It is advisable to start playing witha similar machine where the big pul-ley is absent and the two threads arerolled on the same reel. The childrenwill devise a simpler model; then itwill be easier for them to jump to thetwo-wheel model.

Attaching the threadMaterials Assembling the contraption

The contraption in operation

Construction plan for the thread-lifting contraption

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1. Open an old recording tapecassette.

2. Unblock one end of the tape, cutout most of the tape, leaving 20-25cm, and fix the free end to thewheel again (above centre)

3. Enclose the tape cassette in a box,fixing it with adhesive tape.

4. Make two small holes in the box,corresponding to the two wheelson the cassette. Cover the gears tomake them invisible from outsideand then close the box.

5. Model two suitable pens, adaptingthem to the gears behind the holes.

This contraption is very puzzling forchildren and should be introducedafter the simpler gear and pulleyscontraptions. The tape contraptioncan be complicated further by chang-ing one of the two wheels for a biggerone.

This article deals with science process learning in school, and I rec-ommend it for teachers both in primary and secondary schools.These are practical descriptions of how to construct the black boxeswith hidden contents. There are good examples of different boxesthat can be used with different ages of students according to theirability. Pictures showing the boxes and experiments are provided tohelp the teacher make the black boxes.

Sølve Marie Tegner Stenmark, Norway

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Construction plan for the tape contraption

Reattach the tape to the wheelMaterials The finished tape contraption

Alfredo Tifi teaches at the technicalschool (istituto tecnico industrialestatale) E. Divini San Severino,Marche, MC, ItalyNatale Natale teaches at the middleschool (scuola media) Caiatino,Chiazzo, CE, ItalyAntonietta Lombardi works at theeducation office (direzione didattica),Bernalda, MT, Italy

ReferencesTifi A, Natale N & Lombardi A (2006)

Scientists at play: teaching scienceprocess skills. Science in School 1:37-40. www.scienceinschool.org/2006/issue1/play/

Web referencesw1 - www.scienzainrete.it/unita_

didattiche/marchingegno.htm

ResourcesThe American Association for the

Advancement of Science stresses thatkey science concepts need to be givenin the context of an authentic under-standing of how scientists go abouttheir work to reach conclusions. Foran example, see:www.project2061.org/publications/bsl/online/ch1/ch1.htm

Investigatinggears

Teaching activities

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Dionisios Karounias,Evanthia Papanikolaou andAthanasios Psarreas, fromGreece, describe theirinnovative model of theDNA double helix – usingempty bottles and cans!

This proj-ect to

construct a 3Dmodel of a DNA

molecule, using every-day materials, stimulated

the students’ interest, encour-aged teamwork, dexterity and the

investigation of the properties of mate-rials, and allowed the students toexpress their own opinions and solveproblems. More specifically, studentslearned the basic structural elements ofDNA and their 3D molecular organisa-tion.

Molecular structure of DNA The basic unit of DNA is the

nucleotide, consisting of a phosphategroup, a sugar molecule (deoxyribose)and one of four nucleobases (alsoknown as bases): adenine (A), thymine(T), guanine (G) or cytosine (C). TheDNA molecule consists of successivenucleotides arranged in a double helix– a spiral ladder – the sides of whichare formed from sugar and phosphategroups, with each step consisting of apair of bases. The base pairs are formedfrom complementary nucleotides: ade-nine pairs with thymine, while guaninepairs with cytosine.

Modelling the DNA

double helixusing recycled

materials

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DNA molecule Model

Phosphate group Coca Cola® can

Deoxyribose Sprite® can

molecule

Base Plastic bottle

The model Each of the three constituents of the

nucleotide were represented with 3Dobjects (see Table 1) which were con-nected to form a double helix with tensteps (base pairs). See below.

Table 1: DNA molecular componentsand the corresponding model materials

MaterialsRecycled materials

Our choice of materials reflectedtheir abundance in the school recy-cling bins.

· 20 aluminium Coca Cola® cans

· 20 aluminium Sprite® cans

· 20 plastic Coca Cola bottles (500 ml)

· 60 red caps from Coca Cola bottles

· 10 plastic Fanta® bottles (500 ml)

· 20 orange caps from Fanta bottles

· a thin piece of paper or plastic,approximately 1 m long.

Additional materials· 6 m thin rope

· 20 plastic drinking straws

· 20 nuts and thin double-threadedbolts

· 4 sheets of coloured confectionerycellophane (blue, green, red andyellow).

Tools · Scalpel or sharp knife for cutting

the plastic bottles

· Thick nail for the making holes inplastic and aluminium

· Small pliers

· Stapler

· Two pieces of thin telephone cable,about 40 cm long, for passing therope through the straws.

MethodFirst, each of the three nucleotide

constituents (deoxyribose, phosphateand base) are modelled, reflecting thegeometry of the molecule as far aspossible. Next, the components areassembled to form nucleotides andthe DNA helix is constructed.

Puncture the aluminium cans andthe bottle caps with the same nail.Heating the nail will enable the capsto be more easily pierced. Choose asuitable thickness of nail to enable the plastic drinking straws to passthrough the holes and fit firmly, creat-ing a stable link between the structur-al elements.

DeoxyriboseDeoxyribose is modelled with a

Sprite can with three red bottle capsattached, representing the carbonatoms at the 1’, 3’ and 5’ positions(above right). An orange bottle cap atposition 3’ represents the hydroxidethat will be connected to the nextnucleotide. 1. Puncture the can in positions 1’, 3’

and 5’, as shown above .2. Puncture four bottle caps (three

red and one orange) in the centre.3. Using a nut and bolt, attach a red

cap firmly in position 1’ so that abottle can be screwed on.

4. Firmly attach two caps, one red andone orange, to one end of a straw(first the red, then the orange).

5. Pass the straw through the can,using holes 3’ and 5’.

6. Fix the can to the straw, threadinganother red cap to the side of thecan in position 5’. The final resultcan be seen above right.

Phosphate groupUsing the same nail, puncture the

centre of the Coca Cola can base,which represents the phosphategroup. Thread the straw attached tothe Sprite can (deoxyribose) throughthe Coca Cola can (phosphate group),with the top of the Coca Cola can clos-est to the Sprite can. The phosphategroup is now attached to the deoxyri-bose in position 5’ (see page 26, left).


Teaching activities

Phosphategroup

Deoxyribose

O

O

O

P

CH2

C4’

HCH

H3’

COH

H2

1’

5’

CH

O =O

A nucleotide

Base

5’

1’

3’

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The straw connects the two cans,and also makes it easy to pass the thinrope through both cans, connectingthe nucleotides into a molecule chain(see below). For this reason, it isimportant not to bend the straw. To maintain the correct scale betweenthe molecule and the model, thedistance from the base of the CocaCola can to the orange cap should be 23 cm.

Complementary base pairsNext, plastic bottles representing

the bases are modelled so that theycan only be connected to their com-plementary base (adenine to thymine,and guanine to cytosine).

To construct two complementarybase pairs, cut two Fanta bottles andthree Coca Cola bottles in cross-sec-tion, using the scalpel and scissors.Take care!1. Remove the base of two Coca Cola

bottles (incision c above centre)2. From the third Coca Cola bottle,

removea) the neck, cutting 10 cm below

the mouth (incision a) andb) the lower part of the bottle,

cutting 4 cm above the base (incision b).

Using scissors, make five to sixincisions, 2 cm long, in the neck andthe base of the third Coca Cola bottle.These can then open to allow otherbottles in (see above right).

Using these building blocks and thecoloured cellophane, the structuralelements that represent the bases canbe created (see page 27).

Thymine (T)Place green cellophane in a Coca

Cola bottle without a base.

Adenine (A)To the base of a Fanta bottle, attach

the neck of another Coca Cola bottle.Place blue cellophane inside bothparts.

Thymine (T), represented by thecolour green, is connected by twohydrogen bonds to adenine (A), rep-resented by the colour blue. To modelthis, push the blue neck firmly intothe green bottle without the base.

Guanine (G)Place red cellophane in a Fanta

bottle.

Cytosine (C)Place yellow cellophane in a Coca

Cola bottle without a base. Firmlyattach the base of another Coca Colabottle, upside down.

Guanine (G), represented by thecolour red, is connected by threehydrogen bonds to cytosine (C), rep-resented by the colour yellow. Tomodel this, open the base of the yel-low bottle (cytosine) along the inci-sions to allow the base of the red bot-

tle (guanine) to enter and lock firmly.For symmetry and the scale of the

model, the two pairs of linked com-plementary bases should be 42 cmlong. Each coloured bottle is screwedinto the bottle cap (carbon) at position1’ of a deoxyribose molecule, formingfour different nucleotides (see page 28).

This representation of the hydrogenbonds enables the easy connectionand detachment of complementarybases. This, in turn, facilitates notonly the separation of the DNAstrands but also the change in posi-tion of bases for teaching purposes.

Constructing the DNA molecule Having constructed 20 nucleotides,

we can build a double helix with 10steps – two strands of 10 nucleotideseach. Because the distance from theend of the Coca Cola can (phosphategroup) to the orange cap (hydroxidelinked with the next phosphategroup) is 23 cm, the strand of 10nucleotides will be 2.3 m long.

Attach the telephone cable toapproximately 3 m of the thin ropeand use the stiff cable to pass the ropethrough the straws of the nucleotidesto form two strands of molecules,which are hung vertically 2 m highand 65 cm apart. The two strands ofthe DNA molecule are read in thedirection 5’ to 3’ and are anti-parallel.In the model, the direction in whichwe read the word Coca Cola coincides

Phosphate group

Deoxyribose5’

3’

1’

c

b

a

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with the direction 5’ to 3’. Thus, inone of the strands, the words CocaCola can be read from top to bottomand in the other strand, from bottomto top. Our model DNA strands arethus also anti-parallel.

We must also make sure that thebases on one strand are complementa-ry to those on the opposite strand.Adenine should be opposite thymineand cytosine opposite guanine.

If these criteria have been met, tiea paper roll at the end of each strand

so that a thin bar can be passedthrough the roll and used to twist the linked strands clockwise, 360degrees (see page 28, bottom right).

ScaleThe model represents a DNA

molecule at a scale of 320 000 000:1,that is, 320 million times bigger thanit really is. If we tried to represent anentire human DNA molecule with ourmodel, we would need a double helix 640 000 km long, capable of

wrapping around Earth’s equator 16times.

Using the model in class The model was constructed and used

in three phases over one to two weeks.

Phase 1: Constructing the modelStudents aged 14 followed the con-

struction directions with interest andwere involved in resolving practicalproblems.

Phase 2: Representing a DNAmolecule

In the appropriate unit of their biol-ogy course, students aged 15 weregiven a worksheet where they recog-nised and matched the preparedstructural materials of the model withthose of the DNA molecule as illus-trated in their textbook. They com-posed and twisted the double chain ofthe model. They asked a lot of ques-tions and had an intense and interest-ing discussion.

DNA molecule Model

Diameter 2 nm 0.65 m

Helix step 3.4 nm 1.1 m

Helix length 7.14 nm 2.30 m

Helix length: diameter 3.57 3.53

Helix step: diameter 1.7 1.7

Table 2: Sizes and proportions of a DNA molecule and the model

Teaching activities

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Students learn much more quickly and easily whenthey are actively involved in the lesson. Teaching thestructure of DNA is made much easier if a 3D repre-sentation of the molecule is used. Jigsaw puzzle-typeactivities give a 2D picture, but it is difficult to visualisethe shape of the molecule. This ingenious projectdescribes how a scale model of DNA can be madeusing cans and bottles. It would be easy to collect thematerials required to make this model, as studentscould recycle cans and bottles.

It may be a good idea for a technician or teacher to dosome of the preparation work; this would decrease theamount of time needed in the lesson as well asaddressing safety considerations with the use of a hot

nail to puncture the bottle tops and a sharp implementto cut the plastic bottles. Alternatively, the model couldbe made in a design-technology class and then used inbiology lessons. Group work could be designed so thatteams race each other to prepare a DNA model. Themodel could be used as a teaching tool to demonstrateDNA replication, either in mitosis or in the polymerasechain reaction. The fact that the model is to scale willhelp the students appreciate the spatial relationship ofthe components of the DNA molecule. I feel that stu-dents will enjoy learning about DNA using this idea,which means that the lesson will be both understoodand remembered.

Shelley Goodman, UKRE

VIE

W

Phase 3: Copying a DNAmolecule

In their free time and as a theatre game, the same 15-year-oldstudents pretended to be suitableenzymes and, with the help of the model, performed the followingsteps:1. Splitting hydrogen bonds between

the complementary bases, from thetop of the molecule until the sixthbase (bottle) pair on the model(enzyme: DNA helicase).

2. Separating the two strands.3. Beginning to create daughter

strands complementary to theparental strand (DNA polymerase).

4. Splitting the rest of the hydrogenbonds.

5. Creating daughter strands comple-mentary to the parental strand(DNA polymerase).

6. Checking for possible errors andcorrecting them if necessary.

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The chocolate challengeJohn Schollar from the National Centre

for Biotechnology Education at theUniversity of Reading, UK,

finds an excuse for eatingone of his favouritefoods – chocolate.

Teaching activities

Every country in Europe seems tohave its own favourite chocolate,

and the characteristics of the best-sell-ing brands vary greatly. Thus, milkchocolate with a caramel note domi-nates the English market while theFrench prefer darker chocolate with agreater content of cocoa solids. Howcan different brands of chocolate beobjectively compared, and how canquantitative data be obtained fromsuch comparisons? Here are somesimple yet effective comparative pro-cedures that are widely used in thefood industry. Typically, they are usedfor quality control, to assess changesin the product (for example, as a resultof changes in raw materials or produc-tion methods), to monitor shelf lifeand to assist in the development of

new products. The methods yield datasuitable for statistical analysis and canbe used for chocolate or for other foodproducts such as fruit juice or biscuits.

Preparing the chocolateFor this exercise, you will need a

minimum of three different products.The maximum number of brands youcan compare will be determinedlargely by the time you have avail-able, but in practice it is difficult tocompare more than six products. Weusually find that four different typesof chocolate, carefully selected to givea range of characteristics, are ideal fora classroom activity.

To avoid bias, the chocolate shouldbe presented to the students withoutidentifying the brand. Identify each of

the products with a three-digit codepicked at random so that there is nonumber bias.

Manufacturers’ names are oftenmoulded into chocolate bars, so youmay wish to remove the name to pre-serve the anonymity of each type ofchocolate. This can be done in twoways. We have a laboratory heatingblock set to 40 °C, which we coverwith a clean sheet of aluminium foil.We place the each chocolate bar facedown on the foil for a few secondsuntil the manufacturer’s name hasbeen melted away. If you do not havea heating block, remove the namewith a spoon or knife that has beenwarmed in boiling water; this takes alittle time, but it is effective as mostchocolate melts at about 37 °C.

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Unfortunately theshapes of choco-late bars oftenprovide a clueabout the identityof the brand, soremoving the namemay not be a fool-proof means of ensuringthat the tasters are not biased.

Once the names have beenremoved, cut chocolate into piecesthat are suitable for tasting - we usu-ally provide students with piecesabout 10 mm square.

For each working group, put sam-ples of each type of chocolate intoseparate clean plastic bags, labelledwith the appropriate identificationcode. Provide one sample for eachstudent (we usually ask students towork in groups of four).

Materials and equipment neededby each person· Three or four different brands of

chocolate, cut into small squaresabout 10 mm x 10 mm (one sampleof each type)

· A clean paper plate on which toplace the chocolate samples

· A glass of water for cleaning thepalette after tasting each sample

· Photocopied sheets (pages 31-33)on which to record the results

· A ruler marked in millimetres

· Coloured pencils (a differentcolour for each type of chocolate)

Procedure1. Taste each chocolate sample in

turn, and as you do so, use thesensory testing chart to record thecharacteristics of each brand ofchocolate. Use a different coloured

pencil for each choco-late sample. Take

a sip of waterafter tastingeach sampleto refreshyour palette.

2. Measure the distancesbetween the beginning ofeach line and the colouredmarks you have made onthe lines. Convert the

positions marked for eachcharacteristic for each

chocolate sample into percent-age values, and record these val-

ues in the personal summary table.Note that each line on the firstchart is 100 mm long, so that thepositions marked on the line areeasily converted into percentages.

3. Collate the results for your groupin the group summary table. Notethat it may be easier if you dividethe work and one person collectsall the data for one chocolate type.

4. Calculate the group mean for eachcharacteristic. If desired, you mayalso collect the data for theentire class.

5. In the chart on page33, plot a sensoryprofile (zero at thecentre, 100% at theextremity) for eachchocolate brand. Eachbrand of chocolate willhave a sensory profile repre-sented by a different shape. If youuse coloured pencils for this, allthe data can be shown on onechart.

6. If time allows, the data for theentire class can be collated andcompared. Your personal percep-tion of each chocolate’s characteris-tics can be compared with groupor class results.

7. Finally, discover the identity ofeach of the different brands ofchocolate you have tasted. Look at the ingredients such as milk andcocoa solids listed on the wrappersfor each of the chocolate samples.Try to relate the results you haveobtained to information on chocolate wrapper and any advertising claims made for eachbrand.

SafetyFor reasons of hygiene, wear dis-

posable plastic gloves while you arepreparing the chocolate. The samplesmust be prepared in a kitchen orroom suitable for food preparation,not a laboratory. The chocolate shouldnot be tasted in a laboratory.

IMPORTANT! Teachers should beaware that some students may havefood allergies (e.g., to nuts) and willtherefore be unable to carry out thiswork.

Preparation and timingThe activity takes about 60 minutes.

The chocolate samples should be pre-pared in advance.

ResourcesFurther information about chocolate

manufacture, including prac-tical investigations suit-

able for the school lab-oratory are given in:

Beckett ST (2004)The Science of

Chocolate. London,UK: Royal Society of

Chemistry

Additional information is provided inChapter 12 of:

McGee H (2004) McGee on Food andCooking: an Encyclopedia of KitchenScience, History and Culture. London,UK: Hodder and Stoughton Ltd

A useful compendium of chocolatefacts and figures is provided in:

Ayral D (2001) A Passion for Chocolate.London, UK: Cassell & Co

Science in School Issue 2 : Summer 200630 www.scienceinschool.org

SIS_2_2-37_RZ 10.07.2006 10:32 Uhr Seite 30

Sensory testing chart

For each chocolate sample, mark a point on the line showing where you think the relativestrength of each attribute lies. Use a different coloured pencil for each chocolate sample, orwrite the chocolate’s code above the mark.

NONE A LOT

Aroma COCOA

Aroma MILK

Flavour SWEET

Flavour BITTER

Flavour COCOA

Texture MELTING

Personal summary table

Each line on the sensory testing chart is 100 mm long. By measuring the distances from the left-hand edge to your marks, turn your assessment for each chocolate and characteristic into a percent-age, where 1 mm = 1%. Record your assessment of each chocolate sample in the chart below.

CHOCOLATE SAMPLE CODE

273 475 620 948

Aroma COCOA

Aroma MILK

Flavour SWEET

Flavour BITTER

Flavour COCOA

Texture MELTING


Teaching activities

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Class summary table

OPTIONAL: Collate the results for your class in the table below and calculate the class mean for each characteristic. You will need a separate copy of this table for each chocolate sample.

CHOCOLATE SAMPLE CODE:

GROUP NUMBER

1 2 3 4 5 6 7 8 9 10

Aroma COCOA

Aroma MILK

Flavour SWEET

Flavour BITTER

Flavour COCOA

Texture MELTING

Group mean


Group summary table

Collate the results for your group in the table below and calculate the group mean for each characteristic. Youwill need a separate copy of this table for each chocolate sample.

CHOCOLATE SAMPLE CODE:

GROUP MEMBER NAMES

Aroma COCOA

Aroma MILK

Flavour SWEET

Flavour BITTER

Flavour COCOA

Texture MELTING

Group mean

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Sensory profile

On the chart below, plot a sensory profile (zero at the centre, 100% at the extremity) for each chocolate sample.Each sample will have a sensory profile represented by a different shape. If you use coloured pencils for this, allthe data can be shown on one chart.

Aroma COCOA

Texture MELTING Aroma MILK

Flavour COCOA Flavour SWEET

Flavour BITTER

Teaching activities


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Environmental issues centred onwater are among the key con-

cerns in our modern world; the globalproblem of disappearing wetlandregions is particularly significant.Wetland regions are key habitats inthe preservation of a vast range ofwildlife species, and the health ofsuch regions is an important indicatorof the health of the ‘blue planet’. Thepast 50 years have seen the earth’swetlands reduced by around 50%.

Concern over wetland regions pro-vides part of the background to aseries of cross-curricular studies thatwe have carried out at AiglonCollege, an international school basedin western Switzerland. The collabo-ration between our geography andchemistry departments in carryingout these studies was also seen asimportant, emphasizing the interac-tion between the skills and methodsinvolved in the two subjects. Thestudies were carried out by studentsin their final two years of secondaryschool.

Aiglon’s location close to the east-ern end of Lake Geneva allows usready access to a small, but highlysignificant, wetland region at the

delta of the Rhone where it flows intothe lake. This region of Switzerland isexperiencing rapid urbanisation andthe development of services for thetourist industry, which are puttingincreasing pressure on the fewremaining natural habitats of theRhone plain. The delta wetlands area,known as Les Grangettes, is rich in

wildlife, featuring a great diversity ofreptiles, amphibians, invertebratesand birds. Around 265 bird specieshave been identified in the reserve,including many migratory water-birds. Since 1990, the area has beenrecognized as a wetland of interna-tional importance under the RamsarConvention, but it is still threatenedby the encroachment of human activi-ties and modifications of the naturalenvironment, whether intentional orunintentional.

The scope of the studiesOur studies of this region included

a range of approaches involving landuse surveys, an analysis of the impactof tourism, biodiversity data collec-tion and the assessment of waterquality. To carry out a thorough studyof water quality, it was important tostrategically choose the points in thearea to collect water samples. Watersamples were taken from some 24 dif-ferent sites in the Les Grangettesregion, covering a range of differentlocations – canals, drainage ditches,lake frontage and stagnant pools.

We tested water for a range ofparameters, such as:

Environmental chemistry:water testing as part ofcollaborative project work

Collecting a sample from a canal

Wetlands are key habitats for a vast range of wildlife. RichardHarwood and Chris Starr, from Aiglon College, Switzerland,describe a school project to measure water quality in a localwetlands region.

SIS_2_2-37_RZ 10.07.2006 10:32 Uhr Seite 34


· pH

· dissolved oxygen

· nitrate ion concentration

· phosphate ion concentration

· turbidity

Some of these tests were carried outimmediately in the field, but thesewere also followed up with moresophisticated testing back in the lab.

The type of testing that we carriedout varied from simple test stripmethods for pH and nitrate ion con-centration to electronic sensing (fordissolved oxygen and turbidity, forexample), reflectometric reading oftest strip colours (for nitrate andphosphate ion concentration), and theuse of specific ion electrodes (fornitrate ion concentration). The elec-

tronic sensors were linked to data-log-ging instruments and electronic calcu-lators. The use of this range of meth-ods not only served to check the relia-bility of the methods but also intro-duced the students to the differentlevels of sensitivity available formeasuring these factors.

A major focus was to assesswhether fertilisers were leaching from

Teaching activities

Reed beds in the Okavango Delta – one of Earth’s most unique wetlands

The team minibus serves as a base as wemove around the 24 sites

Testing the water samples – in both the field and the lab. A range of equipment wasused, from pH strips to datalogging sensors

SIS_2_2-37_RZ 10.07.2006 10:32 Uhr Seite 35


surrounding agricultural land into theprotected area. Such leaching wouldresult in eutrophication and its conse-quent impacts on the ecology of thisenvironmentally sensitive area. Thereare strict local restrictions on farmersin the immediate area and we wereable to link our data with that fromthe Grangettes Foundation, the organ-isation responsible for the manage-ment of wildlife conservation in theprotected area.

The analysis of the data from thesetests is of crucial importance inincreasing the usefulness of the study.Applying valid statistical methods tothe analysis of the results is importantin establishing their meaning. Oneaspect of our studies that has pro-duced revealing results on statisticalanalysis was the testing of nitrate lev-els. The choice of the most appropri-ate statistical test is key here, and, as

with the use of practical techniques ofdiffering sensitivity, this gives stu-dents a useful insight into researchtechniques.

Statistical analysis of nitrate ionresults

Our aim was to see if there was anyrelationship between nitrate concen-trations and agricultural activity atdifferent sites. We first conducted astraightforward rank correlation test(Spearman’s, see box) using all of thedata. The test was used to see if therewas any correlation between the dis-tance from the nearest arable landand the nitrate content of the watersample. The results showed no appar-ent correlation.

This led us to consider the differentnature of the sample sites more close-ly. Lakefront sites, part of the largebody of water that is Lake Geneva,

were likely to have very low nitratelevels through dilution when com-pared with, say, drainage ditches.Lakefront samples were therefore dis-counted and the other sites were thenexamined more closely. A pattern didemerge when the origins of the waterin the channels and ponds within thereserve were analysed. The water insome sites had its origin within theboundaries of the reserve, while otherchannels flow in, bringing water thathas drained land outside the reserveboundaries. When the results wereinterpreted with this added informa-tion, it appeared that all the sites thathad measurable nitrate ion concentra-tions contained water originating fromoutside the reserve (see table). On theother hand, water bodies and channelsoriginating within the boundary ofLes Grangettes showed no measurableconcentrations of nitrate.

Statistical analysesThe purpose of the statistical tests used is describedbelow. Details of how the tests are performed can befound in Lenon & Cleves (2001).

Spearman’s Rank Correlation CoefficientThis technique is used to summarise the strength anddirection of any correlation between two variables,such as nitrate [NO3-] content of water and distancefrom arable land. The correlation coefficient (numeri-cal index of correlation) varies from +1 (a perfect pos-itive correlation) to -1 (a perfect negative correlation).A value of 0 indicates no correlation between the twosets of variables. The greater the sample size and num-ber of measurements, the more significant the correla-tion is likely to be. Its significance can be tested byusing a test of significance, such as the t-test.

Remember, this coefficient does not necessarily provea causal relationship between the variables. However,it may suggest that it is worthwhile conducting furtherresearch to uncover the processes which may have ledto the correlation.

Mann-Whitney U-TestThis is a test of statistical significance, used to establishwhether the differences between two sets of data arereally significant or could have occurred by chance.For example, here we are trying to establish whetherthere is a significant difference between the nitrate[NO3-] content in water bodies originating inside thenature reserve, where strict controls on the use of fer-tilisers exist, and that of water originating outside thereserve, which is likely to have been more affected byarable land uses.

Remember, if we find that there is a high probabilitythat the relationship between the data sets could haveoccurred by chance, it may indicate that there is nosignificant difference between the data sets. However,it could also reflect the fact that our sample size wastoo small to produce a significant result.

A statistically significant difference between data setsis obviously a starting point for further investigationinto the processes which may have led to these differ-ences.B

AC

KG

RO

UN

D

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Teaching activities


The reliability of this apparent dif-ference was tested using the Mann-Whitney U-test (see box). The resultsof the Mann-Whitney test indicated aless than 5% probability that the dif-ferences observed between the twotypes of site could have occurred by chance. There was more than a95% probability that the differenceobserved between our samples origi-nating within and outside the reservereflected a wider pattern.

Concluding remarksThe discovery of a statistically sig-

nificant difference between the twotypes of site was important for tworeasons. It was supported by our sub-sequent finding, in an interview withthe Director of the GrangetteFoundation, that there are very strictregulations on the use of fertilisers byarable farmers within the reserve,whereas such restrictions do notapply to farmers outside the reserve.The local farmers seem to abide bythese regulations. Secondly, the stu-dents’ reactions to successful data col-lection and analysis were encourag-ing; it gave us and them much pleas-ure to apply skills from different sub-ject areas to real-life situations.

A number of students took part indifferent aspects of these studies, andthe methods and results formed thebasis of successful examination proj-ects for students taking chemistryand/or geography courses.

Water analysis techniques can beapplied to a variety of local situationsand there are useful websites andInternet-based projects that can beaccessed to give further dimensions tolocal studies. Two such sites are thoseof the GLOBE Programw1 and theGlobal Water Sampling Project w2.

ReferencesLenon B & Cleves P (2001) Fieldwork

Techniques and Projects inGeography. London, UK:HarperCollins

Web referencesw1 - GLOBE Program:

www.globe.govw2 - Global Water Sampling Project:

www.k12science.org/curricu-lum/waterproj/index.shtml

ResourcesAquaData, a school project using five

different methods to measurewater quality (German):www.bionet.schule.de/aquadata/

Information about measuring riverquality, including results for yourlocal (UK) area, can be found on

the UK Environment Agency web-site: www.environment-agency.gov.uk/yourenv/eff/1190084/water/213902/river_qual/?lang=_e

The Water Quality StandardsHandbook from the USEnvironment Protection Agency:www.epa.gov/waterscience/standards/handbook/

This article is an example of good practice for secondary schoolteachers interested in a scientific approach to environmental edu-cation. It is interdisciplinary, involving chemistry, earth sciences,statistics, and a heuristic methodology; focuses on a real situation;and demonstrates the transferability of the situation and the meth-ods used in the study.

The style is plain and clear, so the material can easily be used inlower grades in secondary schools with only minor simplifications.

The web references will enable interested teachers to find furtherinformation and guidance to plan similar experiments in their owncountries.

Giulia Realdon, ItalyRE

VIE

W

Table: Nitrate content at different types of site within the Grangettes Reserve

Site number Nitrate content Site number Nitrate content[water from sources [mg/dm3] [water flowing in [mg/dm3]

inside Les Grangettes] from outside sources]

5 0 2 0

6 0 4 0

11 0 9 8

12 0 10 9

18 0 13 11

19 0 14 9

20 0 17 0

23 9 24 6

Total number of sites 7 Total number of sites 9

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When science is taught out ofcontext and seems irrelevant

to their lives, many students loseinterest. And if a student’s own moti-vation is disregarded, even the mostcareful preparation on the part of theteacher will be wasted. It is crucial,therefore, to highlight the importanceof science and its relevance to stu-dents’ lives. Students also need morepositive and realistic demonstrationsof the scope and limitations of scienceand scientists. Both of these chal-lenges can be addressed by mobilis-ing the scientific and engineeringresearch community.

Some underpinning researchThe UK has a long tradition of

educating and training scientists,engineers and mathematicians who

have contributed greatly to theeconomic stability of the nation.However, even though more youngpeople are entering higher education,fewer students are choosing mathe-matics, physics and chemistry (HESA, 2005), resulting in a skillsshortage. The key to reversing thistrend is to inspire and enthuse youngpeople in science and engineeringthroughout their school education.Mathematics and the physical sci-ences, however, lack positive rolemodels and effective careers advicefor aspiring students (Roberts, 2002;Rasekoala, 2001). A survey of 50schools across the UK showed thatalthough most students enjoyedlearning science at school, fewwanted to study science after school(Bevins et al., 2005). Physics in

particular was seen as complex anddifficult.

“[Physics] is too hard. There are toomany laws and stuff. It doesn’t reallymatter anyway. I will never need thattype of stuff when I start work. You onlyneed to know it if you want to do physicsas a job.”

13-year-old student

Students recognised that access topractising scientists and engineerswould increase their interest andenthusiasm, as well as provide valu-able information on careers and stud-ies. They also felt that an expert in theclassroom would help to put the sub-ject into context and make classroomactivities more exciting.

Promoting scienceand motivatingstudents in the 21st centuryMarilyn Brodie from the Centre forScience Education, UK, describes two projects to involve the scientificresearch community in schools andraise enthusiasm for science amongstudents.

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Projects in science education

“When we’re doing things like gases, ifan expert is in school to help us theycould show us why we use gases and howthey use them in their jobs – that wouldmake [the concept] really interesting.”

14-year-old student

“It would be good to ask them ques-tions about their jobs and find out whatthey do, how they do it and how theylearned to do it – how much they getpaid.”

13-year-old student

Students also suggested that schoolvisits by professionals and to theirworkplaces would help them to learnabout and understand specific profes-sions.

Researcher with students at the RoyalInstitution, London

The Centre for Science Education(http://extra.shu.ac.uk/cse) is one of theUK’s foremost groups in science educationresearch and development, and is thelargest academic group in the field inEurope. Its wide portfolio includes continu-ing professional development, the creationof motivating and innovative interventionschemes, and curriculum development inboth print and digital media.

The Centre for Science Education is com-mitted to reversing the trend away from sci-ence careers and qualifications by inspiringand capturing the imagination of youngpeople in science through the developmentof ‘creativity-rich’ resources and activities.B

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“It would be good to visit a universityto see what they do. It would be exciting.”

12-year-old student

Both the Researchers in Residenceproject and the Express Yourself con-ferences expose students to practisingscientists and engineers, developingthe students’ images of scientists andengineers, as well as of the fields ofscience and engineering.

Researchers in ResidenceResearchers in Residence is a proj-

ect to bring some of the most creativeresearch talents in the UK into sec-ondary schools. The chosenresearchers are fiercely passionateabout their subject and their enthusi-asm can ignite a fresh interest for sci-ence among young people.

PhD students and post-doctoralresearchers in science, technology,engineering and mathematics volun-teer to spend four to five days in sec-ondary schools. They may give class-room support or presentations,arrange visits or attend field trips.After the initial placement, manyresearchers continue their involve-ment with the schools (Brodie &Hudson, 1995).

Among the reasons given byresearchers for their involvement arethe opportunities to: act as a positive

role model (~40% are female); demys-tify research; improve the image ofscientists; and pass on enthusiasm forscience, technology, engineering andmathematics. Furthermore, theresearchers may benefit by improvingtheir communication skills, investigat-ing the world of education and teach-ing, enhancing their CV – or simplyby taking a break from their normalroutine.

“Working with school children andknowing that there is a lot of upcomingtalent”

“I think the programme is a welcomereturn to the ‘real world’ and helps putresearch in perspective. You have a differ-ent view of your thesis topic once youhave had to explain it to young peopleand relate it to the subjects studied andskills learned at secondary school.”

Two PhD students

The project is funded by theResearch Councils UK and theWellcome Trust, and managed by theCentre for Science Education (seebox). Since it began in 1995, theResearchers in Residence project hasrecruited, trained and placed around3500 researchers in over 2000 schools,working with about 2000 teachers and300 000 students.

Express Yourself conferencesCelebrating science and the achieve-

ments of school students not onlyhelps to promote science but also canbe highly motivating for the studentsinvolved.

The Express Yourself conferencesare linked to the Researchers inResidence project. Hosted by researchscientists, these conferences giveschool students a forum in which topresent the findings of their own sci-ence investigations. The conferencesare run similarly to real research con-ferences, with opportunities for stu-dents to:

· Communicate and share their ideaswith other students, teachers andresearchers

· Present research papers in semi-nars chaired by researchers in resi-dence

· Present and host displays of theirinvestigations

· Participate in other activities, suchas discussing their work with expe-rienced researchers, attendingkeynote lectures and demonstra-tions, and participating in practicalworkshops.

SummaryScience teachers and the scientific

community have an important role inpromoting science and raising its pro-file with young people, particularly


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Many countries in Europe struggle to overcome thefalling interest in university science studies. This arti-cle describes two innovative projects to provide stu-dents with a positive and realistic image of science.Bringing researchers into secondary schools moti-vates students by providing them with role modelsand a genuine picture of research. For example, com-municating ideas and results at conferences is anessential part of scientific research – but one that ishabitually overlooked when explaining to studentswhat research actually involves.

The initiatives presented in this article are useful forscience teachers who want to enhance their students’

motivation for science, either by inviting researchersto visit their schools or by organising student scienceconferences. Both projects provide science teacherswith ideas that can be incorporated into classroomactivities and in schools.

Organising such events is time-consuming, butunquestionably worthwhile. Cooperation across sci-ence subjects might give an even more completeimage of scientific research. Ask researchers at yourlocal university to participate in these projects – theytoo will benefit.

Roeland van der Rijst, the Netherlands

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by increasing student participation,motivation and success. This can beencouraged by mobilising profession-al scientists and engineers to supportschool science and by celebrating stu-dents’ achievements in science.

ReferencesBevins S, Brodie E, Brodie M (2005)

UK Secondary School Pupils’Perceptions of Science & Engineering.A report for the Engineering &Physical Sciences Research Council& the Particle Physics & AstronomyResearch Council (unpublished).Available on request:[email protected]

Brodie M, Hudson T (1995) PupilResearcher Initiative: Researchers inResidence. Education in Science 165:18-19

HESA (2005) Qualifications Obtainedby, and Examination Results of, HigherEducation Students at Higher

Education Institutions in the UnitedKingdom for the Academic Year2003/04. SFR PR82. Cheltenham,UK: Higher Education StatisticsAgency

Rasekoala E (2001) African-CaribbeanRepresentation in Science &Technology (ACRISAT). London, UK:National Endowment for Science,Technology and the Arts

Roberts G (2002) SET for Success: The Supply of People with Science,Technology, Engineering andMathematical Skills. London, UK:Her Majesty’s Stationery Office

ResourcesResearch Councils UK is a strategic

partnership of seven UK researchcouncils championing science, engi-neering and technology:www.rcuk.ac.uk

The Wellcome Trust is the world’slargest medical research charity

funding research into human andanimal health: www.wellcome.ac.uk

Researchers in Residence:http://extra.shu.ac.uk/cse/site/projects/cse/rinr

Express Yourself conferences:http://extra.shu.ac.uk/cse/site/projects/cse/pri



Researchers in residence working with school students Help is at hand

If you are interested insetting up a similarscheme in your owncountry and would likeadvice, the Researchersin Residence team wouldbe happy to help.Contact Marilyn Brodie([email protected]).

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The most important thing is tonever stop questioning.” That

was the advice given to a youngstudent by Albert Einstein in 1955. Itwas therefore an appropriate motto to adopt for the exhibition aboard the MS Einstein – Wissenschaft imDialog’s exhibition ship. Beginning on 9 May 2005, the ship travelledthrough Germany, stopping at 36 dif-ferent cities along the way. It finallyended its tour in Basel, Switzerland,on 19 September.

The 105-metre barge had alreadybeen underway with its unusualcargo for a number of years. It wasnot, you see, carrying a load of con-tainers or coal but rather a muchmore sensitive freight: a science exhi-bition designed for a wide audience,including children and young adults.The exhibition theme is chosen eachyear to coincide with the current sci-ence year proclaimed by the GermanMinistry of Education. In 2002, theUniversity of Bremen created theGeoship. Subsequently, the MS Chemie(chemistry, 2003), the MS Technik(technology, 2004) and the MS Einstein

(2005) were floated by Wissenschaftim Dialogw1. The goal of this initiativeby German science organisations is to draw attention to current scientificresearch as well as to encourage alively dialogue between the world of science and the general public.

Two weeks before the planned startof the exhibition, captain AlbrechtScheubner brought the MS Jenny(the ship’s name for much of the year) to the appointed harbour inBremen. The exhibition, which hadbeen planned over the preceding


Imagine a barge carrying not coal or other heavy cargo, butsomething much more precious – inspiration! Beate Langholffrom Wissenschaft im Dialog, Germany, describes a scienceexhibition that travels the rivers of Germany with a differenttheme each year.

The exhibition ship MS Einstein: a floating sourceof scientific knowledge

MS Einstein in Berlin by day

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months, was then rapidly set up on board. Crewed by young scientists, the exhibition was free to visit.

“How fast does time pass?”, “Isthere really nothing faster than thespeed of light?”, “Why will I agefaster on earth than I will in a rockettravelling through space?” Answersto these questions and many morewere to be found on the MS Einstein.

Nine themed zones in the bowels ofthe exhibition ship explained theNobel prize-winner’s theories in sucha way that even non-physicists couldunderstand them. The zones coveredthe photoelectric effect, the generaland special theories of relativity,mass-energy equivalence, stimulated

emission as well as cosmology. Alongthe side of the ship, a time-line reflect-ed aspects of Einstein’s personal life.Finally, Einstein’s failed search for aunified theory of everything wasdemonstrated symbolically throughthe use of a giant three-dimensionaland (almost!) unsolvable woodenpuzzle.

These are only a few examples ofthe numerous interactive stations atthe exhibition. The purpose of thehands-on exhibits was, of course, tohandle and examine them. Curiositydrove a school group to press aroundthe table in the ‘Einstein and me’room. And that was exactly the pointof this room – to awaken curiosityand stimulate the appetite of both


MS Einstein in Berlin by night


Help is at hand

If you are interested insetting up a similar exhibi-tion in your own countryand would like advice, theWissenschaft im Dialogteam would be happy tohelp.

Contact Beate Langholf([email protected]).B

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children and adults for explorationand investigation. The students coop-erated to try to find solutions to thetricky puzzles on display; for exam-ple, try to join nine points (arrangedin rows of 3 x 3) with four straightlines. Everyone wanted to try theirown luck and numerous attemptsfailed. With a helpful hint from one ofthe exhibition’s organisers, however,the students finally succeeded and theresulting euphoria accompanied themto the next table and the next chal-lenge.

The exhibition on the MS Einsteinwas designed for students in grade 9(age 15) and above. Younger childrenwere nonetheless able to stay busyand have fun with the numerousplayful components of the exhibition.

Many teachers had never seen theirstudents so engaged. For the teachers,the visit to the exhibition ship com-plemented their natural-sciences les-sons. The exhibition demonstrated theuses of scientific theories in everydaylife, as well as showing research beingdone in colleges and research centres.The students were thereby able totake a close look at the practical anddaily relevance of scientific work.Classroom knowledge and school-work could be seen in relation to abigger picture.

Some students, of course, refuse tobe enthused by anything. None-theless, there is almost never anytrouble on the exhibition ship: thecontinuous refinement of the interac-tive concepts has gradually succeededin ridding the exhibition of vandal-ism. The mixture of interactivity, sus-pense and concentration has been key.

Among those planning the exhibi-tion ship were representatives fromthe participating science organisations

such as the Fraunhofer Gesellschaft,Helmholtz Gemeinschaft, LeibnizGesellschaft and the Max PlanckGesellschaft. Together with the exhibi-tion agency, they ensured that theproposed exhibits were suitable forexhibiting and developed somehands-on exhibits specially. The over-all goal of the exhibition was to makeup-to-date research findings readilyaccessible to a broad audience.

The fact that the exhibition was on abarge meant that many people attend-ed who would not normally visit ascientific exhibition. The unusuallocation and the fact that it was freealso drew many chance visitors.People who only wanted to take alook often ended up spending manyhours in the floating science centreand showed up again the next daywith friends or family in tow. Theexhibition organisers heard almostnothing but positive feedback.

Young scientists in teams of four‘pilots’ were responsible for answer-ing visitors’ questions and supervis-ing the exhibition. Many have been sothrilled by the work that they comeback year after year. These studentsfrom the most diverse fields of study


Trying to solve the nearlyunsolvable puzzle

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Welcome aboard a scientificcruise on German rivers!

An exhibition ship has been travelling through many cities onGerman rivers each summer with a scientific exhibition. The ideais that what is researched and discovered in laboratories and uni-versities is of interest to all of us because science and researchsignificantly influence the living conditions and culture of oursociety.

The boat (which was originally called MS Jenny but whichchanges its name each year according to the theme of the exhi-bition) is open to school classes and all visitors from May toSeptember. This year’s name is MS Wissenschaft – Sport andComputer Science. Read this article and go on board!

Sølve Marie Tegnér Stenmark, Norway

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were able to gain a familiarity withcommunication and conveying scien-tific subject matter to others. And theywere also willing to accept that, at theend of the day, they might be handeda vacuum cleaner or a screwdriver toensure that everything was ship-shape, ready for the next day.

After about four months and 100 000 visitors, the exhibition wasdismantled: the attendants and organ-isers went home, the exhibits werereturned to their institutions, and theMS Jenny went back to carrying hernormal freight. But the planning con-tinues: the MS Wissenschaft – Sport andComputer Science will use sportingthemes in 2006 to answer questionslike “how does computer sciencefunction?”, “what can it do?” and“where can it be found at work?”w2

So, once again, the slogan will be:science ahoy!

Web referencesw1 – Wissenschaft im Dialog is com-

mitted to ensuring a constant dia-logue between scientists and asmany people and social groups as

possible: www.wissenschaft-im-dialog.de/english/wid.php4

w2 – Details of the MS Wissenschaft’strip in 2006, including a timetable(German): www.ms-wissenschaft.de



View into infinity

Relativistic cycling

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Evaluation ofMutation Effects

DNS SequenceAnalysis


Mariolina Tenchini, Director of Cus-Mi-Bio inMilan, Italy, introduces a university initiativeto motivate science teachers and provideboth them and their students with hands-onexperience of cutting-edge science.

Linking university and school:addressing the challenges ofscience teaching in Italy

Genes andDiseases course

Sequencing

DNA Extractionand PCR

Diagnosis ofGenetic Diseases

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Science teaching in Europe pro-vides many rewards, but also

many challenges. Some of these arefamiliar to teachers in all countries:keeping up with developments inscience, for example, or dealing withdifficult children. Other problemsdepend to an extent on where you are teaching: which country, whichregion or which type of school.

In Italy, unlike in some otherEuropean countries, science teachersare expected to cover the full range ofsciences from geology to molecularbiology, from stoichiometry to astro-physics. Although this offers theopportunity to teach some fascinatinginterdisciplinary topics (e.g. Farusi,2006), it makes it very difficult forteachers to feel confident about theirown knowledge.

Of course, colleagues in the regionmay have the necessary expertise andbe willing to help, but the opportuni-ties to exchange opinions, discussproblems and offer advice are notalways available.

The vast majority of Italian schoolshave little if any money to invest inlaboratory equipment. In schools thathave laboratories, the equipment isoften outdated and unsafe, reagentsare inappropriately stored and wastedisposal is problematic.

Responding to the need for teachersto receive training in the latest scien-tific developments, swap advice, anduse modern and well-equippedlaboratories, the University of Milan,in cooperation with the EducationOffice of Lombardy, has developed a centre for science education in sec-ondary schools: Cus-Mi-Bio. Since2004, Cus-Mi-Bio, the CentroUniversità di Milano Scuola per laDiffusione delle Bioscienze, hasoffered teachers an innovative andstimulating opportunity to combineinstruction in theoretical develop-ments in biology with hands-onlaboratory work.

Cus-Mi-Bio organises activitiesfor both high-school students and

high-school teachers. The two areclosely linked, with teachers helping to develop the courses for the stu-dents.

Courses for teachers and high-school students

Courses for teachers at Cus-Mi-Bioare intended not only to update theirscientific knowledge but also to moti-vate teachers by getting them person-ally involved in the process ofimproving science education in highschools. The topics covered so farinclude recent advances in moleculargenetics, such as genetic engineering,forensic science, the Human GenomeProject, regulation of gene expression,and bioinformatics. The teachers learnabout modern scientific developmentsand work in well-equipped universitylaboratories, and they are providedwith materials and ideas to use intheir own schools. Most of the coursesare in Italian but some, in collabora-tion with the European LearningLaboratory for the Life Sciencesw1,have been in English. Courses con-ducted over the last few years include‘Recent advances in molecular genet-ics’, ‘From organisms to genes: whatzebrafish can tell us’, ‘Genes and dis-eases’, e-learning activities, and‘Bioteach: tools and tips for biologyteachers’.

A key feature is that some of theattendees not only benefit themselvesbut also work together to developresources for all teachers, which arepublished on the Cus-Mi-Bio web-sitew2. Together with university scien-tists, about 50 high-school teachers, incollaborative groups of ten, preparenew materials or tools to be used inschool. The school teachers, therefore,have a dual role: they not only learnnew information, but also use theirexpertise and experience to ensurethat the materials developed areappropriate and interesting for theirstudents.

Once the materials have been pre-pared, the teachers in the collabora-

tive groups test them in their schoolsand provide feedback. Then the nextstep begins: bringing the high-schoolstudents into the University of Milan.Students attend courses in groups of20-25, accompanied by their teacher.The course, ‘Try the BioLab’, consistsof various laboratory activitiesdevised by the collaborative groups.Each student has his or her ownworking space and gains hands-onexperience of working in a laboratory.The accompanying teachers shouldfirst attend a course for teachers onthe same activities, so that they canprepare their students for the course,with the help of handbooks preparedby the collaborative groups.

The courses are run by ‘lead’ teach-ers employed by the Education Office;these are high-school teachers whohave worked in one of the groups todevelop the materials. Additionally,research students from the universitywork as tutors, explaining the equip-ment to small groups of five or sixschool students. The involvement ofthese young scientists is very impor-



Search forEuropeanpartners

Cus-Mi-Bio aims to estab-lish a network of Europeanuniversities working toimprove science educationfor high-school students. Ifyou are interested in set-ting up a similar centre inyour own country andwould like advice, the Cus-Mi-Bio team would behappy to help. [email protected] or [email protected]

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tant, as they act as role models for thestudents and are able to give careersadvice.

The courses are popular with bothteachers and their students; manyteachers return several times with dif-ferent classes. Now in its second year,Cus-Mi-Bio has increased the num-bers of students attending from 1000in the first year to 4000.

Although many of the peopleattending the Cus-Mi-Bio courses arefrom around Milan, participants arewelcome from all over Italy. Atten-dees receive handbooks includingprotocols of the experiments and aCD of information. Teachers unable toattend the courses can still downloadmaterials from the Cus-Mi-Bio website.

Other activitiesCus-Mi-Bio also enables Italian

high-school teachers to attend nation-al or international meetings, wherethey can swap ideas with teachersfrom other backgrounds. In 2005, forexample, one group of teachersattended a summer course in Sweden,while another presented activitiesdeveloped together with Cus-Mi-Bioat a meeting in Germany.

In addition to the ‘Try the BioLab’courses, which are open to all high-school students, Cus-Mi-Bio also offersa work-experience programme for afew selected students. The students,who spend a week working alongsidescientists in the laboratory, all declaredit to be a fantastic experience.

ReferencesFarusi G (2006) Teaching science and

humanities: an interdisciplinaryapproach. Science in School 1: 30-33.www.scienceinschool.org/2006/issue1/francesca/

Web referencesw1 - The European Learning

Laboratory for the Life Sciences(ELLS): www.embl.de/ELLS

w2 - Cus-Mi-Bio:www.cusmibio.unimi.it


After nearly 30 years of teaching science,we still enjoyed it: students are often verystimulating and we both love the subjectswe teach. The chance to join the Cus-Mi-Bio team was a new and exciting chal-lenge. It was a chance to do something webelieved in: to help enthuse our col-leagues and provide them with the mate-rials to teach inspiring lessons in modernscience.

Very important is the friendly atmosphereat Cus-Mi-Bio, where teachers can get toknow each other. We are now a real land-mark for teachers who want advice, infor-mation, or a place to study or exchangeexperiences. The enthusiastic responseshows that high-school teachers neededsomething like this. The two differentworlds of university and school are slowlydrawing closer, thanks to the support ofsome university professors. Working at theinterface is not always easy, but it isalways interesting.

Anna Cartisano and Cinzia Grazioli, high-school teachers working at Cus-Mi-BioB

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A personal slant

Cinzia Grazioli

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Forensic entomology is the studyof insects and other arthropods in

a legal context. The applications arewide-ranging, but the most frequentis to determine the minimum timesince death (minimum post-morteminterval, or PMI) in suspicious deathinvestigations. This is done by identi-fying the age of the insects present ona human corpse, which can provide arelatively precise estimate in circum-stances where pathologists may onlybe able to give a broad approxima-tion. The fundamental assumption isthat the body has not been dead forlonger than it took the insects toarrive at the corpse and develop.Thus, the age of the oldest insects onthe body determines the minimumPMI.

Two examples of this are:

1. A body discovered in the summerin southern England had sufferedextensive burns, making thepathologist’s interpretation of theconventional post-mortemchanges in the body very difficult.Ageing the blowfly larvae on thebody indicated that the first fly

eggs had been laid on the body sixdays before. Witnesses subse-quently testified that the fatal firewas observed on the night beforethe estimated day of egg-laying.

2. A body discovered in late winter innorthern England was well pre-served because of the cold temper-atures, and pathological evidence

Science topics


Forensic entomologyAre you a biologist with a mission? Doyou want to fight crime with science?Martin Hall and Amoret Brandt from TheNatural History Museum in London, UK,introduce the fascinating (and smelly) fieldof forensic entomology.

Female (left) and male (right) adults of the common bluebottle blowfly, Calliphora vicina (Diptera: Calliphoridae)

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suggested that the person haddied two to three weeks before. Incontrast, insect evidence suggestedthat the person had died morethan two months before the bodywas discovered. This was consis-tent with other evidence and wasaccepted by the coroner’s court.

The insects of greatest value toforensic entomology are blowflies(family Calliphoridae), because theyare usually the first insects to colonisea body after death, often withinhours. Because of this, the age of theoldest blowflies gives the most accu-rate evidence of the PMI. Many otherspecies of fly, beetle, wasp and mothare also associated with cadavers,resulting in a succession of insectsarriving at the body, but as they tendto arrive after the blowflies, they areless useful in establishing a PMI.

Blowfly infestations of human bod-ies are a natural outcome of the flies’role in the environment as primarydecomposers. The ubiquity of fly lar-vae on carrion is clear to anyone whocomes across the dead body of ahedgehog or rabbit while walking inthe country. The larval infestationsmight look gruesome, but they are avital component of the natural recy-cling of organic matter and, onhuman bodies, they can provide vitalclues to the timing and cause ofdeath.

Adult blowflies are well adapted tosensing and locating the sources ofodours of decay, so cadavers arequickly found. Eggs are usually laidin the natural orifices (e.g. eyes, nose,mouth, ears) or other dark and moistplaces, such as the folds of clothes orjust under the body. Eggs hatch intofirst instar larvae that grow rapidly,moulting twice to pass through sec-ond and third instars until they finishfeeding. Depending on the species,they pupate on the body or moveaway to find a suitable site. They maymove many metres before burrowinginto the soil or under objects such asrocks and logs or, if indoors, undercarpets and furniture. The larva thencontracts and the cuticle hardens anddarkens to form the barrel-shapedpuparium, within which the pupametamorphoses into an adult fly.When the fly emerges, the emptypuparial case is left behind as long-lasting evidence of the insect’s devel-opment.

The rate of development of allinsects is directly dependent on theambient conditions, particularly tem-perature. Between upper and lowerthresholds, which vary betweenspecies, the higher the temperature,the faster the insects will develop; thelower the temperature, the slowerthey will develop (see graph below).

If the ambient temperatures duringthe period of development areknown, then, in theory, the minimumPMI can be determined.

However, there are many compli-cating factors that affect the rate ofdevelopment of larvae on a body:

· Temperature (which can depend ongeographical location, indoor oroutdoor exposure, sun or shade,time of day and season)

· Heat generated by the maggotmass

· Food source (tissue type, e.g. liver,heart, lungs)

· Contaminants and toxins (externaland internal)

· Burial or other obstructions (e.g.plastic sheets, water) that hinderaccess and egg-laying by adultinsects.

All of the above need to be consid-ered when estimating a PMI, yet formany of them, little information isavailable. For example, the elevatedtemperature due to the maggot masscan be readily appreciated by anyangler reaching into a bowl of baitmaggots, but quantifying its effect onlarval development still requiresdetailed study, for example usingnovel thermal imaging techniques(see box).

The degree to which a forensic ento-mologist is involved in a case can


Life cycle of a calliphorid fly (clockwisefrom bottom left): adults, eggs, first instarlarvae, second instar larvae, third instarlarvae, puparia containing pupae

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Graph showing therate of developmentof the immaturestages of blowflieswith temperature,based on publisheddata for the bluebot-tle blowfly Calliphoravicina (Diptera:Calliphoridae)

Temperature (ºC)

Days from egg-layingto adult emergence

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Science topics


Scientists at The Natural HistoryMuseum, London, UK, are justbeginning to explore the thermaldynamics of larval masses usinginfrared photography. The temper-ature of individual blowfly larvaecan be measured (bottom right).The still-born piglet (above)

appears untouched by insects in anormal photograph, but thermalimaging indicates an active larvalmass in the throat and chestregions (top right) that causes anincrease in temperature where thelarvae are feeding.

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Thermal imaging

Still-born piglet

Temperature of individual blowflylarvae, measured using thermalimaging

Larval mass on the piglet, shownwith thermal imaging

vary. The entomologist may attendthe crime scene personally to collectthe insect specimens from the body orits surroundings. This is ideal,because he or she can use knowledgeof insect biology and behaviour tomake sure that as many specimens aspossible are collected and to helpinterpret the results. Alternatively, theentomologist may collect insect speci-mens during the post-mortem exami-nation as well as viewing photos ofthe crime scene or visiting the sceneafter the body has been removed.Finally, the specimens may be collect-

ed by the police, for example, ideallyafter telephone consultation with theentomologist. Photographs of thescene and the post-mortem examina-tion will then be shown to the ento-mologist.

When investigating a suspiciousdeath, the main questions which needto be answered by the forensic ento-mologist are:

Which species of blowfly are present onthe body? The collected specimensmust be correctly identified, so that allof the relevant information on physi-ology, behaviour and ecology of that

insect species can be used. This ques-tion is answered by taxonomy, one ofthe most neglected of the natural sci-

Author, Martin Hall

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After a zoology degree and a masters in taxono-my and biodiversity,Amoret worked on vari-ous groups of insects,such as hoverflies andwasps, and spent threeyears rewriting TheHandbook of BritishFleas. In search of moreapplied work, leading toa career in entomology,she then moved intoforensics. She is studying part-time for a PhD at King’sCollege London, as well as doing casework in foren-sic entomology at The Natural History Museum.

“I think the most interesting thing about the job is thevariety and uncertainty of it. You never know whenthe phone’s going to ring. Every case is different, andI guess one of the hardest things is never quite know-ing what you’re going to be confronted with.

Casework constantly raises new questions, andmakes you realise how little we know, even about themost common of insects. For instance, a couple ofyears ago, we were asked to visit a crime scene to

search for puparial cases. The problem was that thecrime was two years old, and no research has beendone on how long empty puparial cases remain intactin the soil. So I started a study where I buried a largenumber of empty puparial cases and over a period ofthree years I dig them up. The results should be ableto tell us the rate at which the puparial cases degradeover time, at least over a three-year period. So thenext time we’re faced with an ‘old’ crime, we’ll bebetter able to help.

Probably the most fascinating thing I’ve done is towork at the Anthropological Research Facility (orBody Farmw1, as it is also known) at the University ofTennessee in Knoxville, USA. This is the only place inthe world where the decomposition of humans canbe studied, so it’s an amazing opportunity to study thesuccession of insects on humans, rather than pigs,which is what we usually use.

There’s no obvious route to getting into forensic ento-mology, but I believe that being an entomologist first,and then branching into forensics, is the right way todo it. You need the training and skills of an entomol-ogist to understand the ecology and behaviour of theinsects you’re dealing with.”

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Interview with a forensic entomologist

Searching soil samples from agravesite for insect speci-mens. The initial search at thescene is made on a plasticsheet, before bagging thesamples for further analysisin the laboratory. Note theuse of full protective clothing

Third instar blowfly larvae feeding on a humanbody, many head down, in a maggot mass at a tem-perature approximately 15 ºC above ambient

Author, Amoret Brandt

ences but the foundation for all others.Which are the oldest specimens of

blowfly? They may still be feeding onthe body; they may have left the bodyto pupate elsewhere; or they mayhave already emerged as adults andleft behind their empty puparial cases.

How old are the oldest specimens?Estimating age involves detailed mor-phological study of the insects undera binocular microscope, to determinetheir stage of development and tocompare that with data from standarddatabases relating developmentalstage to age at different temperatures(see next question).

What were the ambient temperatures atthe scene while the flies were developingon the body? An electronic temperature

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data logger is placed at the crimescene for seven to ten days and thereadings are compared with datafrom the meteorological station overthe same period. This comparison andthe data from the meteorological sta-tion for the time before the discoveryof the body can then be used to esti-mate the temperatures during thatperiod at the scene of the crime. Thisdetermines the temperature at whichthe larvae developed.

Forensic entomology is a relativelyyoung science, so there are manyareas which need further investiga-tion. DNA studies are currently beingcarried out to determine genetic dif-ferences between fly species and alsobetween populations of the samespecies, which could help to deter-mine whether a body has been movedafter the initial infestation. Extractingand analysing the gut from larvaewhich have been feeding on a bodymay help determine whether drugswere present in the body, suggesting asuicide or overdose. Gunshot residuein the larval gut would indicate ashooting when physical evidence nolonger exists. It is even possible thathuman DNA could be extracted from

larvae, showing the previous presenceof a body, even when that body hasbeen removed, leaving the larvaebehind.

The most common species ofblowfly can be found all year round,but the effect of cold on the differentlife stages of blowflies has been poor-ly studied. A greater understanding ofthis subject would be valuable, as theslow rate of development in cold peri-ods allows useful PMI estimates to bemade much longer after death than ispossible in summer. Further researchwould help to improve the accuracyand robustness of case reconstructionsbased on forensic entomology.

Web referencesw1 - The Body Farm:

http://web.utk.edu/~anthrop/index.htm

ResourcesReaders interested in forensic ento-

mology are encouraged to consultthe following publications and web-sites for further information:

Byrd JH, Castner JL (eds; 2000)Forensic Entomology: the Utility of

Arthropods in Legal Investigations.Boca Raton, FL, USA: CRC Press

Catts EP, Haskell NH (eds; 1990)Entomology and Death: a ProceduralGuide. Clemson, SC, USA: ForensicEntomology Associates

Erzinçlioglu Z (2000) Maggots, Murder,and Men: Memories and Reflections ofa Forensic Entomologist. Colchester,UK: Harley Books

Goff ML (2000) A Fly for theProsecution: How Insect EvidenceHelps Solve Crimes. Cambridge, MA,USA: Harvard University Press

Greenberg B, Kunich JC (2002)Entomology and the Law: Flies asForensic Indicators. Cambridge, UK:Cambridge University Press

Smith KGV (1986) A Manual ofForensic Entomology. Ithaca, NY,USA: Cornell University Press

American Board of ForensicEntomology: www.research. missouri.edu/entomology/

European Association for ForensicEntomology: http://new.eafe.org

Forensic Entomology: www.forensic-entomology.com

North American Forensic EntomologyAssociation: www.nafea.net

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This article is engaging and fascinating for all teachers, as it dealswith the inevitable decay after death. It gives an interesting insightinto the area of forensic science, which is quite popular today, asshown by many television series on the subject.

The language and the content of the article are easily understood.The biological (entomological) forensic approach is particularlyfascinating, as the most common view of this topic is biochemi-cal or medical. This article shows that you have to work in aninterdisciplinary way to solve crimes. Sherlock Holmes is indeeddead – instead the scientist, police officer and legal team are allnecessary. Maybe this will inspire teachers to work across disci-plines more often?

Unfortunately, any classroom activity with meat and blowflieswould be too disgusting and smelly, but if a creative person couldcome up with a good idea to reduce the bad smell, it would be avery fascinating task for students.

Paula Starbäck, Sweden

Why not take up Paula

Starbäck’s challenge:

can you devise a way to

teach forensic entomol-

ogy in school? Email

your suggestions to

editor@scienceinschool

.org and we’ll publish

the best ideas.

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Everybody will recognize theinkblot above right as being sym-

metrical, but few know that the figurebelow is also considered symmetricalin the precise mathematical sense. So,what is symmetry, really? And whyhas this concept become so pivotalthat many scientists believe it to bethe basis of the laws of nature?

When things that could havechanged, don’t

Symmetry represents immunity topossible alterations – those stubborncores of shapes, phrases, laws, ormathematical expressions that remainunchanged under certain transforma-tions. Consider, for instance, thephrase “Madam, I’m Adam”, which issymmetrical when read back to front,letter by letter. That is, the sentenceremains the same when read back-wards. The title of the documentary,A Man, a Plan, a Canal, Panama, hasthe same property. Phrases with thistype of symmetry are known as palin-dromes, and palindromes play animportant role in the structure of themale-defining Y chromosome. Until2003, genome biologists believed that,

due to the fact that the Y chromosomelacks a partner (with which it couldswap genes), its genetic cargo wasabout to dwindle away through dam-aging mutations. To their surprise,however, the researchers whosequenced the Y chromosome discov-ered that it fights destruction withpalindromes. About 6 million (out of50 million) of the chromosome’s DNAletters form palindromic sequences.These ‘mirror’ copies provide back-ups in the case of damaging muta-tions, and allow the chromosome, insome sense, to have sex with itself –strands can swap position.

For two-dimensional figures andshapes, like those drawn on a piece ofpaper, there are precisely four typesof ‘rigid’ symmetry (when stretching


Everyone knows what symmetryis. In this article, though, MarioLivio from the Space TelescopeScience Institute, Baltimore,USA, explains how not onlyshapes, but also laws of nature,can be symmetrical.

Symmetry rules

...but so is this!

This inkblot is obviouslysymmetrical...

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and distortions are not allowed),known as: reflection, rotation, transla-tion, and glide reflection.

We encounter symmetry underreflection all around us – this is thefamiliar bilateral symmetry that char-acterises animals. Draw a line downthe middle of a picture of a butterfly(see below). Now flip it over, whilekeeping the central line in place. Theresulting perfect overlap indicatesthat the butterfly remains unchangedunder reflection about its central line.Many letters of the alphabet also havethis property. If you hold a sheet ofpaper up to a mirror, with the phrase‘MAX IT WITH MATH’ written verti-cally, it looks the same.

Symmetry under rotation is alsovery prevalent in nature. A snowflake(see below) rotated through 60, 120,180, 240, 300, or 360 degrees about an

axis through its centre (perpendicularto its plane) leads to an indistinguish-able configuration. A circle rotatedthrough any angle about a central,perpendicular axis will remain unal-tered.

Symmetry under translation is thetype of immunity to change that isencountered in recurring, repeatingmotifs, such as the one at the bottomof page 54. Translation means a dis-placement or shift, by a certain dis-tance, along a particular line. Manyclassical friezes, wallpaper designs,rows of windows in high-rise apart-ment buildings, and even centipedes,exhibit this type of symmetry.

Finally, the footprints generated bya left-right-left-right walk are sym-metrical under glide reflection (seeright). The transformation in this caseconsists of a translation (or glide), fol-lowed by a reflection in a line parallelto the direction of the displacement(the dotted line).

All of the symmetries discussed sofar are symmetries of shape and form– ones that we can actually see withour own eyes. The symmetries under-lying the fundamental laws of natureare in some sense closely related tothese, but instead of focusing on formor figure they address a differentquestion: what transformations can beperformed on the world around usthat would leave unchanged the lawsdescribing all observed phenomena?

Symmetry rulesThe ‘laws of nature’ collectively

describe a body of rules that are sup-posed to explain literally everythingwe observe in the universe. That sucha grand set of rules even exists wasinconceivable before the 17th century.Only through the works of scientificgiants such as Galileo Galilei (1564-1642), René Descartes (1596-1650),and in particular, Isaac Newton (1642-1727), did it become clear that a merehandful of laws could explain a widerange of phenomena. Suddenly,things as diverse as the falling of

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A butterfly’s bilateral symmetry

A snowflake is symmetrical under rotation

Footprints are preservedby glide reflection

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apples, tides on the beach, and themotion of the planets all fell underthe umbrella of Newton’s law of grav-itation.

Similarly, building on the impres-sive experimental results of MichaelFaraday (1791-1867), the Scottishphysicist James Clerk Maxwell (1831-

1879) was able to explain all the clas-sical electric, magnetic, and light phe-nomena with just four equations!Think about this for a moment – theentire world of electromagnetism infour equations.

The laws of nature were found toobey some of the same symmetrieswe have already encountered, as wellas a few other, more esoteric, ones. Tobegin with, the laws are symmetricalunder translation. The manifestationof this property is simple: whetheryou perform an experiment in NewYork or Los Angeles, at the other edgeof the Milky Way or in a galaxy a bil-lion light-years from here, you will be

able to describe the results using thesame laws. How do we know this tobe true? Because observations ofgalaxies all across the universe shownot only that the law of gravity is thesame there as here, but also thathydrogen atoms at the edge of theobservable universe obey precisely

the same laws of electromagnetismand quantum mechanics as they obeyhere on Earth.

The laws of nature are also symmet-rical with respect to rotation – thelaws look precisely the same whetherwe measure directions with respect tonorth or the nearest coffee shop –physics has no preferred direction inspace.

If it were not for this remarkablesymmetry of the laws under transla-tion and rotation, there would be nohope of ever understanding differentparts of the cosmos. Furthermore,even here on Earth, if the laws werenot symmetrical, experiments would

have to be repeated in every laborato-ry across the globe.

A word of caution is needed to dis-tinguish between symmetries ofshapes and symmetries of laws. Theancient Greeks thought that the orbitsof the planets around the sun weresymmetrical with respect to rotation:circular. In fact, it is not the shape ofthe orbit, but Newton’s law of gravitythat is symmetrical under rotation.This means that the orbits can be (andindeed are!) elliptical, but that theorbits can have any orientation inspace (see left).

In my opening paragraph, I made astatement stronger than merely say-ing that the laws obey certain symme-tries; I said that symmetry may be thesource of laws. What does this mean?

The source of natural lawsImagine that you have never heard

of snowflakes before, and someoneasks you to guess the shape of one.Clearly, this is an impossible task. Forall you know, the snowflake may looklike a teapot, like the letter S, or likeBugs Bunny.

Even if you are given the shape ofone ray of the snowflake (below, a)and are told that this is part of itstotal shape, this is not much help. Thesnowflake could still look, for exam-ple, like the configuration below, b. If


Newton’s law of gravity may be symmetrical under rotation, but this doesn’t mean theorbits are

Trying to reconstruct a snowflake

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you are told, on the other hand, thatthe snowflake is symmetrical underrotations through 60 degrees about itscentre, this information can be usedvery effectively. The symmetry imme-diately limits the possible configura-tions to six-cornered, twelve-cornered,eighteen-cornered, and so on, snow-flakes. Assuming, based on experi-ence, that nature would opt for thesimplest, most economical solution, asix-cornered snowflake (page 56, c)would be a very reasonable guess. Inother words, the requirement of thesymmetry of the shape has guided usin the right direction.

In the same way, the requirementthat the laws of nature would be sym-metrical under certain transforma-tions not only dictates the form ofthese laws, but also, in some cases,necessitates the existence of forces orof yet undiscovered elementary parti-

cles. Let me explain, using two inter-esting examples.

One of Einstein’s main goals in hisexplanation of general relativity wasto formulate a theory in which thelaws of nature would look preciselythe same to all observers. That is, thelaws had to be symmetrical underany change in our point of view inspace and time (in physics, this isknown as ‘general covariance’). Anobserver sitting on the back of a giantturtle should deduce the same laws asan observer on a merry-go-round orin an accelerating rocket. Indeed, ifthe laws are to be universal, whyshould they depend on whether theobserver is accelerating?

Although Einstein’s symmetryrequirement was certainly reasonable,it was by no means trivial. After all, amillion whiplash injuries per year inthe United States alone demonstrate

that we feel acceleration. Every timean aeroplane hits an air pocket, wefeel our stomachs leap into ourthroats – there appears to be anunmistakable distinction betweenuniform and accelerating motion. So how can the laws of nature be thesame for accelerating observers, whenthese observers appear to experienceadditional forces?

Consider the following situation. If you stand on bathroom scalesinside an elevator that is acceleratingupward, your feet exert a greaterpressure on the scales – the scales willregister a higher weight (above, a).The same would happen, however, ifgravity somehow became stronger ina static elevator. An elevator accelerat-ing downward would feel just likeweaker gravity (above, b). If the ele-vator’s cable snapped, you and thescales would free-fall in unison, and

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Weight control, elevator style – gaining weight when the elevator accelerates upward (a), losingweight when it accelerates downward (b) and achieving weightlessness when it free-falls (c)

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Dr. Mario Livio, a Senior Astrophysicist at the Space TelescopeScience Institute, gives a very interesting account of the symmetryof the laws of nature. For figures and shapes drawn on a piece ofpaper, there are four types of symmetries: reflection, rotation,translation, and glide reflection. How can these be applied to thelaws of nature? Are the laws of nature symmetrical? And whichtransformations can be performed on them so that the laws remainunchanged?

Although not directly connected with curriculum material forschool science, this article will surely interest all science teacherswho would like to improve their understanding of the laws thatgovern the universe. Mathematics teachers would find this articleof particular interest.

Elton Micallef, Malta

the scales would register zero weight(above, c). Free-fall is therefore equiv-alent to someone miraculouslyswitching gravity off. This ledEinstein in 1907 to a ground-breakingconclusion: the force of gravity andthe force resulting from accelerationare in fact one and the same. Thispowerful unification has been dubbedthe ‘equivalence principle’, implyingthat acceleration and gravity are real-ly two facets of the same force – theyare equivalent.

In a lecture delivered in Kyoto in1922, Einstein described that momentof epiphany he had in 1907: “I wassitting in the patent office in Bernwhen all of a sudden a thoughtoccurred to me: if a person falls freely,he won’t feel his own weight. I wasstartled. This simple thought made adeep impression on me. It impelledme toward a theory of gravitation.”

The equivalence principle is really astatement of a pervasive symmetry;the laws of nature – as expressed byEinstein’s equations of general relativ-ity – are the same in all systems,including accelerating ones. So whyare there apparent differencesbetween what is observed on a merry-go-round and in a laboratory at rest?General relativity provides a surpris-ing answer. They are differences onlyin the environment, not in the lawsthemselves. Similarly, the directionsof up and down only appear to bedifferent on Earth because of theEarth’s gravity. The laws of naturethemselves have no preferred direc-tion (they are symmetrical under rota-tion); they do not distinguish betweenup and down. Observers on a merry-go-round, according to general rela-tivity, feel the centrifugal force that isequivalent to gravity. The conclusionis truly electrifying: the symmetry ofthe laws under any change in thespace-time co-ordinates necessitatesthe existence of gravity! This explainswhy symmetry is the source of forces.The requirement of symmetry leavesnature no choice: gravity must exist.

Dr. Mario Livio is a SeniorAstrophysicist at the Space TelescopeScience Institute (STScI; Baltimore,MD, USA), the institute which con-ducts the scientific programme of theHubble Space Telescope.

His interests span a broad range oftopics in astrophysics, from cosmolo-gy to the emergence of intelligent life.He has done much fundamental workon the topic of accretion of mass ontoblack holes, neutron stars, and whitedwarfs, as well as on the formation ofblack holes and the possibility toextract energy from them. During thepast few years, his research hasfocused on supernova explosions andtheir use in cosmology to determinethe nature of the ‘dark energy’ thatpushes the universe to accelerate, andon extrasolar planets. His latest popu-lar book, The Equation that Couldn’t beSolved, discusses symmetry.

This article was first published in alonger form in Plus, a free online maga-zine which aims to introduce readers tothe beauty and applications of mathemat-ics. The original article can be read here:www.plus.maths.org/issue38/features/livio/index.html

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The use of chocolate by humansdates as far back as the Pre-clas-

sic period (900 BC to AD 250). Usinghigh-performance liquid chromatog-raphy, scientists have discoveredcocoa residues in Mayan ceramic potsused in food preparation, datedaround 600 BC (Hurst et al., 2002).Numerous Mayan murals and ceram-ics are inscribed with hieroglyphs

depicting chocolate poured for rulersand gods. Perhaps this is not surpris-ing, considering that the Latin namefor the cacao tree, Theobromacacao,means ‘food of the gods’.

When chocolate was introduced to Europe in the 16th century by theSpanish conquistadors, a sweetenedversion became a luxury itemthroughout the continent. In 1847,

the first commercial chocolate barswere invented in England by JosephStorrs Fry, with the Cadbury brothersfollowing soon after.

Ever since, chocolate has beenabsorbed into the fabric of daily life;however, few are familiar with theways in which it affects our body. Themedia’s message about chocolateremains confusing, as reports alter-

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Dhara Thakerar, asecond-year student ofnatural sciences atCambridge University, UK,elucidates the science ofchocolate.

Chocolate’s chemical charm

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nate between scrutinising chocolatefor health risks and praising it forhidden health benefits. So, is themantra of ‘eating just a piece a day’more detrimental than beneficial?

The pleasurable feelings that choco-late induces can be explained by itsphysical properties. Professor JohnHarwood and his colleagues atCardiff University believe that thehigh stearate content of cocoa butter,a key ingredient in chocolate, isresponsible for its melting behaviourand stability. Cocoa butter containsbetween 30% and 37% stearate in itslipid content. As a result, it is solid atroom temperature, but when con-sumed, its fat content absorbs heatfrom the mouth and melts at bodytemperature, producing the ‘melt inthe mouth’ effect.

Chocolate has long been suspectedof having aphrodisiac properties: theAztecs thought it invigorated menand made women uninhibited.Consistent with this, the chemicaltryptophan is found in chocolate. Thisis used in the brain to make serotonin,the neurotransmitter that can producefeelings of ecstasy. However, trypto-phan is present in chocolate in onlysmall quantities, fuelling debate as towhether it causes the elevated pro-duction of serotonin.

Phenylethylalanine, which pro-motes feelings of attraction, excite-ment, giddiness and apprehension,

has also been isolated in chocolate, butagain, its low concentration may beinsufficient to produce the effects typi-cally associated with this compound.

Theobromine – a weak stimulantfound in chocolate – in concert withother chemicals such as caffeine, maybe responsible for the characteristic‘buzz’ experienced when eatingchocolate. Scientists at the Neuro-sciences Institute in San Diego sug-gest that chocolate contains pharma-cologically active substances that pro-duce a cannabis-like effect on thebrain, such as anandamide: a cannabi-noid neurotransmitter (Di Tomaso etal., 1996). Chocolate also contains N-oleoylethanolamine and N-linoleoy-lethanolamine, which inhibit thebreakdown of anandamide, and thusmay prolong its effects. In addition,elevated levels of the neurotransmit-ter can intensify the sensory proper-ties of chocolate (texture and smell),thought to be essential in inducingcravings.

The high fat content of most choco-late – Cadbury’s Dairy Milk alone con-tains 30 g of fat per 100 g – means thatexcesses can contribute to obesity,which carries with it a range of healthrisks, including heart disease and dia-betes. Nevertheless, not all accusationslevelled at chocolate can be justified.The often-touted link between choco-late and acne has been intensivelystudied for three decades. In a 1969 study at the University ofPennsylvania School of Medicine, 65subjects with moderate acne ate eitherchocolate bars containing ten times theamount of chocolate found in a typicalbar or identical bars containing nochocolate. Test subjects who consumedthe excessive amount of chocolate forfour weeks did not show signs ofincreased acne (Fulton et al., 1969).

Additionally, chocolate has not beenproven to contribute to cavities ortooth decay. Cocoa butter may in factcoat teeth and help protect them bypreventing plaque formation.


Editor’scomment

Now that you’ve graspedthe theory of chocolate,it’s time for the practicalwork! See our chocolate-tasting activity on page29.B

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Although the sugar in chocolate con-tributes to cavities, it does so no morethan the sugar in other sweet foods.However, by altering blood flow tothe brain and releasing norepineph-rine, some chemicals in chocolate cancause migraines.

Perhaps the best compromise is tosnack in moderation, particularly ondark chocolate. Not only does it con-tain more cocoa and proportionallyless sugar and fat than milk chocolate,but it is also full of antioxidants calledflavonoids. In fact, dark chocolate hasbeen reported to contain moreflavonoids than other antioxidant-rich foodstuffs, such as red wine.Flavonoids reportedly prevent can-cers, protect blood vessels, promotecardiac health, and counteract mildhypertension (high blood pressure).

Milk chocolate may not offer thesame benefits. In one study, patientson separate days ate 100 g of darkchocolate,100 g of dark chocolate witha small glass (200 ml) of whole milk,

or 200 g of milk chocolate (Serafini etal., 2003). One hour later, those whoate dark chocolate alone had the high-est concentration of antioxidants intheir blood, suggesting that the milkin milk chocolate may interfere withthe absorption of antioxidants.

Science can explain a number offeatures that contribute to the lastingpopularity of chocolate, although howsome of its post-consumption effectsoccur is still debatable. Although it isunlikely to ever be marketed as ahealth product, eating the darker vari-eties and snacking in moderationcould prove beneficial. But one thingis certain: from both scientific andsensory perspectives, there is nothingquite like chocolate.

ReferencesDi Tomaso E, Beltramo M, Piomelli D

(1996) Brain cannabinoids in choco-late. Nature 382: 677-678.doi:10.1038/382677a0

Fulton JE Jr, Plewig G, Kligman AM(1969) Effect of chocolate on acnevulgaris. Journal of the AmericanMedical Association 210: 2071-2074

Hurst WJ et al. (2002) Cacao usage bythe earliest Maya civilization.Nature 418: 289-290

Serafini M et al. (2003) Plasma antiox-idants from chocolate. Nature 424:1013

ResourcesFor more information on the science

of chocolate, see the BBC’s HotTopics website: www.bbc.co.uk/science/hottopics/chocolate

Professor John Harwood’s research isdescribed here:www.cf.ac.uk/biosi/research/molecular/staff/harwood.html

This article was first published inBlueSci, a science magazine based atCambridge University: www.bluesci.org

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M m m . . . c h o c o l a t e !Everybody loves it. And itis potentially good foryou; that is, of course, if itis dark and in small quan-tities. This is what theshort but highly interest-ing and enlightening arti-cle by Dhara Thakerarsuggests, citing scientificevidence to support hercase.

Although the details of thechemical substances inchocolate might bebeyond the secondaryschool level, their effectson the body and healthcan be easily understoodand appreciated. This arti-cle can thus be directlyused in any science classto inform students aboutthe advantages and disad-vantages of eating choco-late. Furthermore, biologyand chemistry teachersmight find the article suit-able for a discussion onhow a single type of foodcan be either beneficial orharmful depending onhow, by whom and forwhat purposes it is used.In fact, a debate could becarried out with groups ofstudents acting as propo-nents or opponents of thehabit of eating chocolate.

Finally, if the theoreticaltreatment of the subject isconsidered insufficientand needs practical inves-tigation, all the teacherhas to do is to take a boxof dark chocolate into theclassroom...

Michalis Hadjimarcou,Cyprus

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How epigenetics shapes life“ … it is tempting to wonder if this

twisted sugar string of purine and pyrim-idine base beads is, in fact, God.”

James WatsonMore than 50 years have passed

since James Watson and Francis Crickfirst published the 3D structure of theDNA double helix. With Darwinianevolutionary theory now so wide-

spread, the discovery that DNAencodes hereditary characteristics hasproven popular. When Crick passedaway in 2004, broad media coveragesignified how much these conceptsare accepted beyond the scientificcommunity. However, we are comingto realise that gene-centric theories ofevolution are limited in their scope.The genetic blueprint, like a complex


EpigeneticsWe tend to think of our genetic informa-tion as being encoded in DNA – in ourgenes. Brona McVittie from EpigenomeNoE, UK, describes why this is only part of the story.

Chromatin

Image created by Nicolas Bouvier;courtesy of Genevieve Almouzni,Curie Institute, Paris, France

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musical score, remains lifeless with-out an orchestra of cells (players) andepigenotypes (instruments) to expressit.

Science is now uncovering whatplays our genetic score, and it appearsthat this performance can change dra-matically between generations with-out any alteration to the DNAsequence. The field of epigeneticsseeks to determine how genome func-tion is affected by mechanisms thatregulate the way genes are processed.Epigenetic factors include both spatialpatterns, such as the arrangement ofDNA around histone proteins (chro-matin), and biochemical tagging.

There are hundreds of differentkinds of cells in our bodies. Althougheach one derives from the same start-ing point, the features of a neuron arevery different from those of a livercell.

With some 30 000 genes in thehuman genome, the importance ofsilence, as in any orchestral perform-ance, must not be underestimated. Ascells develop, their fate is governedby the selective silencing of genes.This process is subject to epigeneticfactors. Patterns of DNA methylation,the addition of a methyl group, play arole in all sorts of phenomena inwhich genes are switched on or off,from the splash of purple on a petu-nia petal to the growth of canceroustumours.

Failure to silence genes can producea hazardous cacophony. AbnormalDNA methylation patterns can alterthe spatial arrangement of chromatin.This, in turn, affects which genes aresilenced after cell division.Hypermethylation can inhibit thework done by protective tumoursuppressor genes and DNA repairgenes. Such epimutations have beenobserved in a wide range of cancers.These epigenetic insights are offeringnew therapeutic avenues for explo-ration.

Epigenetics also provides a meansby which genetic material can

respond to changing environmentalconditions. Although plants do nothave a nervous system or a brain,their cells have the ability to memo-rise seasonal changes. In some bienni-al species, this ability is linked to theircapacity to flower in the spring, whenwarmer ambient temperatures aredetected. Research has shown howexposure to cold during winter trig-gers structural changes in chromatinthat silence the flowering genes inmouse-ear cress. These genes are reac-tivated in spring when longer daysand warmth are more conducive toreproduction.

The environment can also promptepigenetic changes that affect futuregenerations. Recent laboratory studieson inbred mice demonstrated howchanges to their diet might influencetheir offspring. Their fur can bebrown, yellow or mottled dependingon how the agouti gene is methylatedduring embryonic growth. Whenpregnant mothers were fed methyl-

rich supplements such as folic acidand vitamin B12, their young devel-oped mainly brown fur. Most of thebabies born to the control mice (notgiven the supplements) had yellowfur.

Just as the conductor of an orches-tra controls the dynamics of a sym-phonic performance, epigenetic fac-tors govern the interpretation of DNAwithin each living cell. Understandingthese factors could revolutionise evo-lutionary and developmental biology,and thus affect practices from medi-cine to agriculture. To answer Watson,“The genetic alphabet is more akin tothe word of God, and its translationto His hand.”

Twin profiles“At times in their lives they have

definitely striven to be perceived as aunit and at other times seem to wantpeople to acknowledge their differ-ences and respect them as individu-als,” says Jim of his friends Gavin andJason. Gavin and Jason are identicaltwins. One is literally a clone of theother.

Their similarities cannot be disput-ed, but when I first met them, I foundthem to be quite different people. HadI met them a few years earlier, I doubtI would have been able to tell themapart.

Monozygotic (identical) twins occurwith an incidence of 1 in every 250births worldwide. For reasons yetunknown, a fertilised egg cell clonesitself and gives rise to separateembryos. Each will begin and end lifewith the same genetic make-up, butas they grow and develop they willexperience differences in their envi-ronment, some of which might altertheir appearance and behaviour.

Gavin and Jason have exactly thesame DNA. If one committed a crimeand unwittingly left samples forforensic analysis, it would be impossi-ble to determine the culprit fromDNA fingerprint analysis. However,closer inspection of their molecules

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The twins aged 29: Jason (left) andGavin on the beach

The twins aged 7: Jason (left) and Gavinwith their mother and grandmother

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may reveal significant differences.Although the two share the samegenes, recent evidence suggests thatsome genes might be active in onetwin but not the other. They might beidentical genetically but not epigeneti-cally.

Such differences are discernable atthe molecular level in the way thattheir chromosomes are arranged with-in the nucleus of each cell. Twistedaround tiny protein (histone) balls,the same DNA string can have differ-ent consequences for a cell. Both ballsand string assume complex 3D struc-tures depending on their biochemicalflavour. A variety of small moleculescan affect the nuclear infrastructureby adhering to DNA and its associat-ed histone proteins. Such flavours areinfluenced by the environment, mostnotably our diet.

Biochemical fine-tuning of thegenome determines which genes areswitched on, so twins are not neces-sarily destined to share the same fate.Recent research (Fraga et al., 2005) onaround 80 different sets of monozy-

gotic twins has revealed that theirDNA is marked in different ways by atiny molecule called methyl. So it’snot really true to say that they areidentical. What’s more, these differ-ences were much more pronounced inolder than in younger twins.

This is new fodder for the age-olddebate over how much the environ-ment influences our fate relative toour genes. Although the similaritiesbetween identical twins are morestriking than the differences, theirinequalities could offer new avenuesfor disease research. For example,although Gavin and Jason are both atrisk for type II diabetes, Jason wasrecently admitted to hospital with apancreatic infection and had to injecthimself with insulin for some timeafterwards. The doctors were unableto make a more specific diagnosis.Had they been equipped with betterdiagnostic tools, such as those offeredby new advances in epigeneticresearch, they might have been able toprofile the twins to ascertain whatwas wrong with Jason.

ReferencesFraga MF et al. (2005) Epigenetic dif-

ferences arise during the lifetime ofmonozygotic twins. Proceedings ofthe National Academy of Sciences USA102: 10604-10609. doi:10.1073/pnas.0500398102

ResourcesFurther information about epigenetics

is available on the multilingualEpigenome NoE website:www.epigenome.eu

Traditionally, identical twins are considered identicalin all aspects of their make-up, right down to the wayin which their DNA functions. The debate over natureversus nurture has persisted for many years, with manystudies looking at identical twins who have been sepa-rated at birth and raised in different environments tosee how they differ. At last there appears to be concreteevidence that nurture or environmental pressures influ-ence how DNA is methylated or silenced in thegenome, leading to minute changes in gene expres-sion. These epigenetic changes, affecting the arrange-ment of DNA around histone proteins and its biochem-ical tagging, can be influenced by something as simpleas diet or, in plants, by seasonal changes. The discov-ery of this phenomenon means that identical twinscould, for example, react differently to the same med-icine. Investigating how genome function is affected by

gene silencing is thus an emerging and important field.

Although the control of gene expression in terms of the‘lac’ operon is included in some syllabuses, DNAmethylation as a mode of gene control is not consid-ered within the UK A-level biology syllabus. It is men-tioned in text-books in the context of bacterial DNAbeing methylated to prevent its own restrictionendonucleases from cutting endogenous DNA. Theidea of silencing genes by methylation could be intro-duced into genetics lessons as ‘how identical are iden-tical twins?’ Most students should be aware of thenature versus nurture debate in the upbringing oftwins, but this can now be extended. It may also bepossible to introduce the concept of DNA methylationinactivating one of the X chromosome in females.

Shelley Goodman, UKRE

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Spotlight on education

The GRID project, GRowingInterest in the Development of

teaching science, aims to create anetwork of decision-makers andschools to exchange good practices in European science teaching. Theprimary objective is to identify,analyse and promote primary- and

secondary-school initiatives to makescience teaching attractive. The ulti-mate aim is to disseminate the bestpractices thus identified via awebsitew1.

The first stage of the GRID projectwas to analyse European educationpolicies with a direct impact on

schools. This was done by reviewingpolicy reports, recommendations andinstitutional plans published by min-istries, regional and local educationauthorities, and educational institu-tions. This report is currently beingfinalised and will be available on theGRID website.

GRID: a Europeannetwork of good practicein science teachingSibylle Moebius introduces a project,GRID, to identify and promoteinnovative science education in Europe.

Sir Harry Kroto at a workshop for primary school children in Waterford, Ireland

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Via the GRID website, a major sur-vey has been launched to identify andanalyse existing school initiatives toincrease the attractiveness of science.If you are a science teacher in a pri-mary, lower or upper secondaryschool who is involved in an isolatedclassroom-based initiative, or who isrunning a major local, county, region-al, national or even international proj-ect, we encourage you to participatein the survey.

In each of the partner countries, thesix to 12 best projects will be selectedas case studies. The purpose of thecase studies is to maximise the impactof existing projects and encouragetheir spread across Europe. The casestudies will include video clips andinterviews with the teachers involved.

Subsequently, workshops will beorganised in each partner country, in

which teachers can sharetheir experiences and

offer advice to oth-ers interested insetting up simi-lar science edu-cation projects.

The first resultsThe GRID survey of innovative sci-

ence education projects in Europe hasalready identified some particularlyinspiring projects.

Physics is Cool (Belgium)The University of Antwerp has

developed a project for secondaryschools called ‘Physics is Cool’w2.Some 40 kits contain all the materialsneeded to carry out a wide range ofexperiments with 14-17 year-old stu-dents. A teacher’s guide and a CD arealso included. The experiments areintended to provoke discussion andimprove scientific communicationbetween students, to make themaware of the causes of everyday phe-nomena, and to confront them withexperiments which are rather easy todo but sometimes difficult to explain.

The Ada Lovelace Project:mentoring for women in scienceand technology (Germany)

Female university students in sci-ence, engineering and mathematicsact as mentors to schoolgirls as part ofthe Ada Lovelace Projectw3. The men-tors are trained in communicationand moderation methods, with super-vision by pedagogy or psychologystaff. They visit schools and discussreasons to study science, engineeringand mathematics, offer advice onovercoming obstacles, and inform theschool students about university life.As a second step, the mentors invitegirls to participate in universitycourses and laboratory work.

Life Learning Center (Italy)The main goal of the Life Learning

Centerw4 is to provide teachers andschool students with hands-on labora-tory experience of the life sciences atuniversity. They learn about modernmolecular biology, genetics andbiotechnology, and use advanced lab-oratory equipment with the supportand supervision of university tutors.

Chemistry at Work (UK)Chemistry at Workw5 events demon-

strate to school students the impor-tance of chemistry in everyday lifeand work, with particular emphasison what is happening in their localarea. The events offer a positiveimage of the chemical sciences andpresent them as exciting, interestingand financially beneficial activitiesthat are worth considering as thebasis of a career.

Updates on the GRID projectThe GRID newsletter, available on

the GRID website or by email, isaimed at project partners, scienceteachers, decision-makers, contribu-tors and all others involved and inter-ested in the project. It documents theproject and its activities and events,and provides partners and contribu-tors with practical information. To


Children enjoying ScienceWeek at the WaterfordInstitute of Technology,

Ireland

Pupils investigating solar power

CALMAST chem-istry display at the

Young Scientist andTechnology Exhibition,Ireland

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subscribe to this free newsletter, sendan email to Sibylle Moebius ([email protected]) with your name, sur-name, profession, country and emailaddress.

AcknowledgementsThe GRID project is funded within

the framework of the EuropeanCommunity Socrates Programme,coordinated by the Pôle Universitaire

Européen de Nancy-Metz, France,and carried out by a European multi-disciplinary consortium.

Web referencesw1 – GRID website:

www.amitie.it/gridw2 – Physics is Cool:

http://webhost.ua.ac.be/focus/Koffers/english.htm

w3 – The Ada Lovelace Project:

www.uni-koblenz.de/~alp/projekt_en.htm

w4 – Life Learning Center:www.golinellifondazione.org/eng/

w5 – Chemistry at Work:www.rsc.org/Education/chemwork/

Spotlight on education


All images courtesy of GRID partner Sheila Donegan,CALMAST, Waterford Institute of Technology, Ireland

Chamber of Challenges atthe Waterford Institute of

Technology, Ireland

Eoin Gill at the CALMAST stand at theYoung Scientist Exhibition, Ireland (left)

Primary school pupils at the YoungScientist Exhibition, Ireland (right)

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Through the glass windows of histiny office, you can see four or

five members of Detlev Arendt’sresearch team pipetting, scribbling intheir lab notebooks, and preparingexperiments. Detlev ventures out intothe lab every day, but he feels most athome at his desk, surrounded bystacks of books and journal articles.

“By nature I’m more of an armchairscientist,” he says. “I could easilyspend my whole day reading andwriting. But the best science comesfrom a marriage of theory and labwork. You can have great ideas, butwhen you produce data, things oftenturn out differently than you imag-ined, and the end result is more beau-tiful.”

Even Charles Darwin, fresh off theship HMS Beagle, had to put in histime at the microscope; he was toldthat a “serious biologist” had to havestudied one organism exhaustivelyand contributed original work on it.As a result, he dedicated himself for adecade to a creature which, until then,had received little attention: thebarnacle.

The armchair approach has beenunusually successful for Detlev, start-

ing during his third year of biologystudies at university. He says he wasa “typical undergraduate”, not terri-bly concerned about a career. Hechose biology because in school hehad been attracted to the most com-plicated topics he could find, andbiology was certainly complicatedenough.

Detlev had also considered workingin ecology. He had been introduced tothe field during an 18-month periodof civil service that young Germanmen can choose instead of militaryservice, when he had given guidedtours of the North German seashore.“It’s a fascinating habitat,” he says.“The tide runs out, and you can walkfor kilometres and kilometres amongthe mud flats, finding millions ofworms, mussels and snails that youdon’t see anywhere else.” But when itcame to deciding which subject toconcentrate on at university, Detlevfelt that ecology didn’t offer enough,and he chose biology instead.

When it came time to write his the-sis, he went to the library to read.Two topics that interested himtremendously were evolution anddevelopment: how animals’ bodies


A search for the origins of the brainDetlev Arendt, a molecular biologist at theEuropean Molecular Biology Laboratory,Heidelberg, Germany, describes to RussHodge how his cutting-edge research isfollowing in the footsteps of a 19th-centuryscientist.

Detlev Arendt

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grow from single egg cells. At thetime, these two fields had started tocome together on the molecular level,following in the footsteps of a 19th-century German scientist namedErnst Haeckel.

“Haeckel put forward the idea thatas an individual animal body forms, itgoes through phases that resemble thehistory of its evolution as a species.So human embryos start off as singlecells, then go through stages that firstresemble very simple multicellularanimals, then worms, fish and mam-mals, before they finally take on aform that is uniquely human.”

A century later, scientists began tounderstand that tissues and bodystructures arise when young cells acti-vate new sets of genes, changing theirshapes and interactions, building tis-sues and organs. Molecular develop-mental biology and genetics werecoming together in a new researchfield called evolution and develop-ment – or ‘evo-devo’.

In the early 1990s, as Detlev sat inthe library, this new field was in itsinfancy. One amazing study revealedthat a particular family of genes hadbeen conserved through nearly a bil-lion years of evolution in all sorts oforganisms. Called the homeobox(HOX) genes, they lay down the basichead-to-tail organisation of the bodyplans of widely diverse animals. HOXgenes are arranged next to each otheron a chromosome, like a string ofwords making up a sentence. As cellsin the early embryos of animalsdivide, HOX genes are activated oneafter another, in the order in whichthey appear on the chromosome. Theresult is the step-by-step formation ofthe head and lower segments of thebodies of worms, flies and humans.

Were other body parts built usingancient blueprints like the HOXgenes? “People went looking for pat-terns,” Detlev says. “For example,they had discovered molecules thatformed the ventral and dorsal – upperand lower – sides of flies. Then they

began looking for relatives of thesegenes in mammals. They found mostof the crucial ones, and there was lit-erature about how mutations in thesegenes affected the body plans ofmammals. But at first there didn’tseem to be a strong parallel betweeninsects and vertebrates.”

Detlev read paper after paper insearch of similarities between miceand flies. As he stared at two paperslying side-by-side on his desk, oneabout insects and the other aboutmice, a pattern suddenly leapt out athim.

“Maybe there was a simple geneticprogramme to determine these sidesafter all,” he says. “All you had to dowas make one assumption – that thegenes that formed the ventral side ofinsects were forming our dorsal side,and vice versa. In other words, atsome point in evolution, vertebrateshad flipped over.”

Detlev raced through all the litera-ture he could find on genes that guid-ed these developmental processes.Everything he found suggested thathe was right. So he checked theresults with one of his teachers at the

University of Freiburg, KatharinaNübler-Jung. She encouraged him tosend a letter to one of the most impor-tant scientific journals in the world –Nature.

The result was something almostunheard of – Nature printed a scientif-ic communication from an undergrad-uate student. Scientists everywherepeered more deeply into Detlev’shypothesis, even seeing patterns intheir own data that they had missed.He began to receive invitations toconferences all over the globe. Notonly was it exciting to be invited to somany places – it also gave him a the-sis topic.

Detlev walks me from his office,through the lab, then down the hall-way to another room. Here are aquar-ia full of his favorite organism: asmall marine worm called Platynereis

dumerlii. Detlev brought the animal toEMBL when he began doing postdoc-toral work in the lab of JochenWittbrodt.

Detlev was working on a fascinat-ing question: he wanted to discover

Scientist profile


Jochen Wittbrodt and Detlev Arendt

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the very early evolutionary origins ofthe brain. This was an excellent matchwith Jochen’s work, he says, becauseJochen was interested in studying theorigins of the eye. And if you go backfar enough in evolution, it’s really thesame question.

To explain this, he takes down around dish containing some wormsswimming energetically. This simplecreature holds important clues to theorigins of our own brain. “All livinganimals with brains and eyes – frominsects to humans – descend from oneancestor; Platynereis descends from itas well,” he says. “That ancestor hada symmetrical body plan from head totail: the right and left half mirroredeach other. Before it evolved, therewere other forms of life that didn’thave this symmetry, like sponges.”

Some features of this worm resem-ble that ancestor more than today’sinsects and vertebrates, making itsomething like a “living fossil”. ThePlatynereis brain is like a blueprint forwhat insect and vertebrate brainshave in common, and thus for thebrain of their common ancestor. Bystudying its development, Detlevhopes to discover how the first brainsarose.

Where does the brain come from?The question can mean two differentthings, Detlev says. The first is howour species’ brain evolved. The sec-ond is how an individual’s braingrows from a single cell. Very recent-ly, following in the footsteps of ErnstHaeckel, scientists like Detlev havebegun to connect these two stories.


Platynereis dumerlii

The 49th plate from Ernst Haeckel’s Kunstformen der Natur (1904), showing varioussea anemones classified as Actiniae

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A fertilised egg divides over andover, differentiating into specialisedtypes of cells like blood, muscle andneurons, which form all of our tissuesand organs within the space of ninemonths. This happens because ourgenetic code contains instructions forproducing tens of thousands of differ-ent molecules, like a huge recipebook. Although every cell in our bod-ies contains a copy of the entire book,each type draws on only a subset ofthe recipes, producing a unique cock-tail of molecules that determines itsshape and behaviour. Modern tech-nology allows scientists to analysethat protein cocktail, yielding a“molecular fingerprint” that identifiesthe type of cell. This permits them todiscover cells that are just on theverge of becoming the first nervesand parts of the brain, long beforethere are any recognizable organs.

Detlev is convinced that the molec-ular fingerprint can also be used tofind related cells among differentspecies. Over nearly a billion years,he believes, evolution has held ontothe basic recipe for creating the majorcell types and organs. Similar celltypes in different animals will sharethe most important ingredients of thecocktail because they were inheritedfrom a common ancestor. So if youcan find those cells in insects, fishand mammals, and then pin down acommon recipe, you most likely havethe original cocktail for buildingbrains. The patterns can be tested bychecking them against what happensin Platynereis.

It’s a new method that changes theway biologists are learning about evo-lution, and Detlev thinks it has solveda great debate about one of Darwin’sevolutionary riddles: how manytimes nature “invented” the eye. Evenafter the closest scrutiny of cells fromdifferent species under the electronmicroscope, scientists came to manydifferent conclusions – estimatesranged from two to 40 different acts of“evolutionary invention” for eyes.

The fingerprinting method has per-mitted Detlev, Jochen and manyenthusiastic PhD students to clear upsome of the confusion. “I’d be lostwithout my students,” Detlev laughs.Starting with the key genes involvedin making light-sensitive cells ininsects, they checked for related mole-cules in the genomes of mammals andfish. Then they began scanning earlylarvae of Platynereis, probing for cellsthat used these genes. A patternemerged: in all of these different

species, the same recipe was beingused to make two fundamentally dis-tinct types of photoreceptor cells. Soeven though the eyes of today’sinsects and vertebrates look very dif-ferent- even down to the architectureof the cells that compose them – theycan be traced back to these two typesof light-sensitive cells.

The project has also given the scien-tists a detailed view of how evolutioncan generate different organs from thesame basic cell types. Photoreceptorcells are used to create many differentstructures; different branches of lifeseemed to have spun off the cell indifferent ways. But they are all some-how related to the eye and its connec-tions to the brain.

The work with Jochen has nowgiven Detlev – “and my enthusiasticstudents” – the tools they need totackle the question of brain evolution.Doing so will require a healthy mix ofideas and data. That’s nothing new inthe science of evolution. Evidence thatspecies could change had been knownfor a long time; it took a young manabout Detlev’s age to step back fromthe data, retreat to his armchair, andweave it all together into a coherenttheory. So it shouldn’t come as a sur-prise that taking care of CharlesDarwin’s unfinished business, from150 years ago, will require a similarapproach.

Scientist profile


Detlev’s researchgroup: HeidiSnyman, KristinTessmar, PatrickSteinmetz andDetlev (clockwisefrom top left)

The 98th plate from Ernst Haeckel’sKunstformen der Natur (1904), depictingorganisms classified as Discomedusae

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From the field to the laboratory“Science is fun!” I thought, aged

seven, when I first read KonradLorenz’s King Solomon’s Ring. “I wantto be a scientist when I grow up!” Ididn’t change my mind during mytime at school, and so, many yearslater, I found myself as a biology stu-dent at the University of Milan, withthe impossible mission of writing athesis on a mathematical model todescribe the formation of armies inslave-maker ants.

After a couple of months filmingants in a national park in northernItaly, sleeping in a tent and walkinghours every day to reach the ant nest,I spent countless hours analysing mydata in front of the computer screen.Then, in the summer of 1996, Ireceived my biology degree and,thinking that nothing could be betterthan being paid to have fun, I happilystarted a PhD in invertebrate biology.

My new research was on sperm insmall annelid worms called Tubifextubifex, commonly found in pollutedand smelly streams. I spent most of

my time playing with immunocyto-chemical techniques, fluorescence andconfocal microscopes, and gettingexcited about pictures of wormsperm. But my first passion, the ants,had not been forgotten, and in 1998, Itook a break from my PhD to spendsix months at the University of Bathdeveloping a mathematical model ofactivity patterns in ant nests.

As often happens, the projectturned out to be quite complex andthe available time was very short, butI was lucky to find a good researchgroup to work with, and I learned avery important thing: the collabora-tive nature of science. Discussingideas and distributing work accordingto individuals’ different abilities isindeed the basis of research.

In 2000, I earned my PhD onannelid reproduction and, afteranother year working on the samesubject, my curiosity led me towardsmolecular biology and the study ofthe human genome. But (in everygood story, there is a ‘but’), aftermany stimulating years of research,

travel and meeting people, I wantedto spend more time with my family.Furthermore, it was clearly going tobe very difficult to find a permanentposition in academia: it was time tomove on.

In the same period, I became inter-ested in the public perception of sci-ence. I first thought about teachingscience at school, because I would beable to enjoy science together with mypupils. Although I would missresearch, the curiosity and wonder ofyoung people would add a new zestto science. I was lucky enough to beawarded a permanent position as ascience teacher and, almost before Iknew what had happened, I foundmyself standing for the first time infront of a classroom of 15-year-olds inan Istituto Professionale, a vocationalItalian high school.

Into the classroom“Science is fun,” I thought, as I

smiled confidently at the pupils. But Iwasn’t smiling a few minutes later as,during the usual first-day interview, I


A zoologist at school: my pupils and other animalsSilvia Boi, a science teacher from Italy,explains how her fascination with scienceled her to study ant behaviour, wormreproduction and the human genome –and how she now tries to awaken thatfascination in her pupils, using somewhatunusual techniques.

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asked the pupils to introduce them-selves and their opinions of science.“Science is boring,” they replied.“Science is difficult,” and, more dan-gerous than any other criticism, “sci-ence is useless”! In less than half anhour, I was involved in a discussionabout why they should learn somescience even though their professionalcurriculum did not specificallyrequire any scientific knowledge.

The second day was better. I beganto lecture and, as the pupils werequite prepared to deal with boredom,they happily occupied themselveswhile I tried to communicate theexceptionality of living systems.

One surprise for the scientist mov-ing to teaching is the amount ofbureaucracy: forms to fill in for everypupil and for the whole class, evaluat-ing their knowledge, behaviour andneeds; tests and questionnaires for thepupils, all written in incomprehensi-ble jargon. Schools often seem to bemore concerned with bureaucracythan with how much their pupilslearn. Sometimes, even the pupils

seem to be interested in the teacheronly as a marking machine: “What’smy mark for this answer?”

Where to start? How to convincestudents that science is useful,accessible and fun? The school whereI work, like many in Italy, has noscience lab, and for safety reasons, no experiments may be performed in the classrooms.

There are no microscopes, noglobes, no stellar maps, no anatomicalmodels or tables. The only resourcesavailable are a computer lab, a TVand a projector. The first idea I hadwas to use simple models to explainthings. I showed my students an atommade out of little coloured balls ofPlasticine®. I represented a cell with a box of different components (a bat-tery representing mitochondria, aninstruction manual representing theDNA in a plastic bag to represent thenuclear membrane and so on...). AndI let them act out the Big Bang.

Then I tried to talk less and let thepupils try to solve a problem. Forexample, I gave them a balloon and

asked them to identify the position of a point drawn on it, hoping theywould draw a system of lines similarto the latitude and longitude. I alsotried to make the tests more fun, aswhen I asked an astonished class ofteenagers to pretend to be the diges-tive or circulatory apparatus. Afterthe initial shock, they accommodatedthemselves to the demands of anabsolutely mad teacher and made cos-tumes to play the part of the liver orthe heart.

Does this work? Honestly, I have noidea. The pupils learn some science,some of them even learn quite a lot,but I cannot say whether these tech-niques are better than traditional lec-tures. What I know for sure is that weall enjoy the science classes! That’s afirst step, and an important one. I’mstill new to this, but you have to learnfast when you awaken students’ inter-est.

Of course, some things about teach-ing would be easier if we had the lat-est equipment and more time dedicat-ed to science in the curriculum. Butmy school is probably typical of manyacross Europe, where every day,teachers make use of what they have– if it’s your hands and feet, you canstill gesture and dance. What I missmost is a community of science teach-ers to discuss and compare methods.

For me, the most rewarding thingabout teaching is not the equipment,but the creativity you can express inthis work, which is stimulated byyour pupils. In every class, you candiscover science through their eyesand try a different method toapproach the same concepts. And as a trained scientist, I think I can trans-mit the taste and excitement of doingscience!

Teacher profile


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Video-clip collectionof the EuropeanSpace Agency

Films about science or even pseudo-science can be powerfultools in the classroom. Heinz Oberhummer from the Cinemaand Science project provides a toolkit for using the video-clipcollection of the European Space Agency.

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In the classroom, video clips aboutscience or even pseudo-science can

be used to stimulate discussion andraise interest in scientific subjects. TheCinema and Science (CISCI)websitew1, due to launch in December2006, will describe a wide variety offilm scenes, providing explanations

and background information to helpteachers prepare inspiring, film-basedlessons.

This article on the video-clip collec-tion of the European Space Agencyw1

(ESA) provides a sample of the con-tent being developed by CISCI,including explanations for pupils andbackground information for teachers.

The Hubble Space TelescopeThe Hubble Space Telescope is a

collaboration between ESA andNASAw2. It is a long-term, space-based observatory. The observationsare carried out in visible, infrared andultraviolet light. In many waysHubble has revolutionised modernastronomy, not only by being an effi-cient tool for making new discoveries,but also by driving astronomicalresearch in general.

The website of the Hubble SpaceTelescopew3 provides a wealth ofimages and video clips to view anddownload.

Basic explanationComets consist of ice and dust and

are therefore often called ‘dirty snow-balls’. When comets approach theSun, the ice melts and boils and parti-cles are thrown out. These particlesare then dispersed by wind from theSun, forming the characteristic comettail. Tempel 1 is a cigar-shaped cometabout 224 cubic kilometres in size.

In the video clip, we see the impactof the 370-kilogram projectile(impactor) released by the motherspacecraft Deep Impact with the innerpart of the Tempel 1 comet on July 4,2005. The comet is named after ErnstWilhelm Leberecht Tempel, who dis-covered it in 1859. The mission isnamed after the film Deep Impact, a1998 blockbuster film.

The impact on the comet Tempel 1was observed by the spacecraft, theHubble Space Telescope and observa-tories around the world. First resultsshow that there is about twice asmuch dust than ice in the comet, sug-

Science in film


Distant view of the comet Tempel 1,the target of NASA’s Deep Impactmission (artist’s impression)

Comet Tempel 1 observed in visible light and infrared light (artist’s view)

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gesting that comets are ‘icy mudballs’,rather than ‘dirty snowballs’, as previ-ously believed.

Advanced explanationMission Deep Impact

Some of the scientific questions thatthe Deep Impact mission was designedto answer were:

· What are the basic properties ofthe comet: how is its surfaceformed, how dense is it, howstrongly is it held together andhow massive is it?

· What is the composition of thecomet?

· Can the course of a comet bealtered to reduce the effect of, or toavoid, a collision with Earth?

The asteroid ApophisOn the evening of April 13, 2029,

the asteroid Apophis, with a volumeof 320 cubic kilometres, will passEarth at a distance of only 36 650 kilo-

metres. This is about the height of ourgeo-stationary satellites and about tentimes closer than our moon. Apophiswill then be visible with the nakedeye over Europe.

On April 13, 2036, Apophis willthen pass Earth at a height of only3400 kilometres (about half Earth’sradius). According to present calcula-tions, the chance of it hitting Earth isabout 1:8000. It would crash into thePacific Ocean with a speed of about50 000 kilometres an hour, correspon-ding to an explosive force of about100 million tons of TNT. It wouldcreate a 2500-metre-deep crater in the ocean, causing tsunamis up to 20 metres high. The Asian tsunami in

2004 was only half that high. Thecosts in infrastructure alone alongthe North American coast wouldamount to approximately US$400billion. However, sustained globaleffects are not anticipated.

The asteroid Apophis is namedafter the Egyptian god of evil,destruction and darkness. Two of theco-discoverers of the asteroid, RoyTucker and David Tholen, are fans of the TV series Stargate SG-1; it isprobable that they named the asteroidafter a character in this series, playedby the actor Peter Williams (seewebsite about character Apophis inStargate SG-1, below).


Cinema andScience(CISCI)

The CISCI project involvesten partners from Europeand the USA, and is part ofthe larger NUCLEUS proj-ect funded by theEuropean Commission.The planned 160 contentunits will cover physics,biology, chemistry, mathe-matics, informatics andother science subjects andwill be available on theCISCI websitew1 in Englishand the languages of theCISCI partners.B

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Table 1: Details of the video-clip collection of the European Space Agency

Title Video-clip collection of the European Space Agency

Description of film Collection of astronomical clips

Film producer European Space Agency

Scientific subject and topic Physics and astronomy

Website www.spacetelescope.org/videos

Purchase film www.spacetelescope.org/hubbleshop/webshop/webshop.php?show=sales&section=cdroms

Table 2: Deep Impact scene details

Time interval heic0508f.mov 0:00:00 - 0:00:18

Scientific keywords Comet, asteroid, impact

Title of scene Deep Impact probe slams into comet

Description of scene Animation showing the collision between the 370-kilogram projectile released by the spacecraft Deep Impact and the comet Tempel 1 on July 4, 2005

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Redirecting ApophisNASA is now making plans to land a transponder on

the asteroid Apophis. A transponder is a tracking systemsimilar to the ones used in commercial aircraft. Thistransponder could then determine the exact trajectory ofApophis, after which the asteroid could be hit and redi-rected using a spaceship with a mass of about 4 tons, toreduce the risk of an impact with Earth in 2036. In princi-ple, this is possible and was demonstrated on a smallerscale by the mission Deep Impact.

Science in film


Web referencesw1 – European Space Agency (ESA): www.esa.int

w2 – National Aeronautics and Space Administration(NASA): www.nasa.gov

w3 – The Hubble Space Telescope: www.spacetelescope.org

ResourcesWebsites about the mission Deep ImpactNASA Deep Impact – science and technology, results, gallery

and news:http://deepimpact.jpl.nasa.gov/home/index.html

Deep Impact, Wikipedia – scientific background:http://en.wikipedia.org/wiki/Deep_Impact_%28space_mission%29

Websites about ApophisDownload a widget that counts down to the possible

impact of Apophis with Earth:www.widgetgallery.com/?search=apophis&x=0&y=0

NASA Earth Risk Impact Summary of Apophis:http://neo.jpl.nasa.gov/risk/a99942.html

Apophis in Stargate SG-1, Wikipedia:http://en.wikipedia.org/wiki/Apophis_%28Stargate%29

The Spirits of Nature by Ottar Vendel – article aboutEgyptian gods: www.nemo.nu/ibisportal/ 0egyptintro/1egypt/index.htm

Websites about asteroidsNASA Lunar and Planetary Science – Asteroids:

http://nssdc.gsfc.nasa.gov/planetary/planets/asteroidpage.html

Asteroid, Wikipedia – scientific description:http://en.wikipedia.org/wiki/Asteroid

Asteroid Introduction – basic summary of comets,

including images: www.solarviews.com/eng/asteroid.htm

Asteroids – educational site about comets:www.windows.ucar.edu/tour/link=/asteroids/asteroids.html

NASA/ESA Hubble Space Telescope Video Archive for‘Asteroid’: www.spacetelescope.org/bin/videos.pl?searchtype=freesearch&string=Asteroid

Websites about impacts of comets or asteroidsImpact event, Wikipedia – scientific description:

http://en.wikipedia.org/wiki/Impact_event

Earth Impacts Effects Program – calculate theenvironmental consequences of impacts on Earth:www.lpl.arizona.edu/impacteffects/

Solar System Collisions – calculate the effects of impacts ondifferent planets: http://janus.astro.umd.edu/astro/impact/

Websites about Deep Impact (film)Internet Movie Database – background information:

www.imdb.com/title/tt0120647/

Websites about Stargate SG-1(TV series)Internet Movie Database – background information:

http://us.imdb.com/title/tt0118480/

Stargate SG-1, Wikipedia – scientific description:http://en.wikipedia.org/wiki/Stargate_SG-1

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Power, Sex, Suicide: three words thatimmediately aroused my interest inreading this book. The subtitle,Mitochondria and the Meaning of Life,explains what the book is about – thecrucial role of mitochondria in ourlives.

This book is not appropriate foryoung students just starting to studybiology, but for higher-level studentsand their teachers, it is fascinating. Iwould recommend it for all students,teachers and others who are interest-ed in questions like: How did lifeevolve? Why do we have sex and twosexes? Why and how do we age?

For those who studied biologysome decades ago, or who are search-ing for new insights into the meaningof life, this book is full of recent scien-tific research and some speculative,but plausible, conclusions about thestory of life. A useful glossary willhelp the reader to understand biologi-cal terminology.

The author’s main theme is that theendosymbiotic event that took place2 billion years ago is the most impor-tant event in the evolution of life.Mitochondria were originally a kindof bacteria living independent lives.Endosymbiosis, a process in whichmitochondria were engulfed by largercells and became organelles insidethose cells, then enabled the develop-

ment of multicellular and more com-plex organisms. Without this remark-able event, no eukaryotes or morecomplex life forms would haveevolved. Without mitochondria, theworld as we know it would not exist.

Nick Lane begins his book by dis-cussing the origin of life and the ori-gin of the eukaryotic cell. Then we aretaken to the world of bacteria andArchaea. Why have bacteria remainedresolutely bacteria for millions ofyears, while an unusual unionbetween a bacterium and an archaeoncreated the eukaryotic cell? The‘power’ described in the book’s titlecomes from the mitochondria them-selves, as Lane describes in detailhow they synthesize ATP through theelectron-transport chain and oxida-tion/reduction.

Lane then deals with why sex aroseand the origin of the two genders.When two cells fuse at fertilisation,there is competition between the twosets of mitochondrial DNA to popu-late the new individual.Mitochondrial DNA is inherited asex-ually down the maternal line, and theauthor suggest that this is the originof the two genders.

The culmination of the book is thediscussion on ageing and the ‘clock oflife’. Given the higher mutation ratein mitochondrial DNA than in nuclear

DNA, the author suggests that mito-chondrial mutations contribute toageing and disease, and that apopto-sis (cell suicide) is necessary to dis-pose of damaged cells. Most impor-tantly, degenerative diseases could beslowed down by slowing down therate of free-radical leakage from themitochondria.

This is a wonderful book not onlyfor learning more about mitochon-dria, but also for addressing impor-tant questions: Who are we? Why arewe here on earth? Why do we havesex? Why are there two sexes? Whydo we fall in love and have children?And why must we grow old and die?This enlightening book provides agood starting point for fruitful discus-sions of all these questions.

DetailsPublisher: Oxford University Press

Publication year: 2005

ISBN: 0192804812

Power, Sex, Suicide:Mitochondria and the Meaning of Life

By Nick Lane

Reviewed by Sølve Tegnér Stenmark, Malakoff Upper Secondary School, Moss, Norway

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Reviews


The Science Behind Medicines CD-ROM is a teaching resource producedby GlaxoSmithKline and aimed atbiology and chemistry teachers ofpost-16 students. It has sections ondrug discovery, structural formulae,bacterial infections, asthma and viralinfections.

The material has been mapped to anumber of science courses at both tra-ditional and vocational GCSE and A- levels in the British education sys-tem. Despite the stated age range, ele-ments of the CD-ROM could be usedas lesson ‘starters’ for younger stu-dents who are studying the basics ofmicrobes or disease.

The section on bacteria details theuses, classification and structure ofbacteria. This goes on to look at dis-eases caused by bacteria and howthey are fought. The development ofpenicillin, how antibiotics work, bac-terial resistance and recent advancesto combat this are explained.

The section on asthma has an intro-duction to the disease, and includestopics such as the role of adrenaline,cell receptors and their function, bron-chodilators and the improvementssought for new bronchodilators.

In the section on viral infections,many aspects of viruses are discussed:viral structure, mechanism of host-cellinfection, antiviral drugs, HIV, AIDS,influenza, and the future of antiviraldrugs. To clarify explanations, thestructure of DNA is also described.Historical aspects of both viral and

The ScienceBehind Medicines

Reviewed by Tim Harrison, School of Chemistry, University of Bristol, UK

bacterial infections are not forgotten.A piece on the discovery of the struc-ture of DNA is also included.

To make it easier for students tounderstand the text, a comprehensiveglossary of terms is available through-out the resource, which activateswhen the mouse rolls over highlight-ed terms.

The section on structural formulaetakes the user through several stagesto read and draw molecular formulaefrom ethane to penicillin G. This sec-tion is useful for those who are not yetexperienced in representing moleculesin this way, as structural formulae areused throughout the other sections.

The only disappointment with thisotherwise excellent CD-ROM is thatsections of text and images cannot becopied. This limits its use, as studentscannot use it to prepare revisionnotes, projects or presentations.Nevertheless, The Science BehindMedicines CD-ROM should be includ-ed on school servers everywhere andcopies could also be made available inschool libraries.

DetailsPublisher: GlaxoSmithKline

Information about the CD-ROM andother free resources fromGlaxoSmithKline is available here:www.gsk.com/community/supporting_education/free_resources.htm

OrderingCopies of the CD-ROM are available

free by [email protected]

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A professor once told me in a jobinterview that he prefers to hirewomen for his laboratory “becausethey get things done”. Nonetheless,although a blunt question as towhether you plan to have children iscertainly out of fashion, female scien-tists still experience situations that arepolitically incorrect. As long aswomen hold fewer than 20% of senioracademic positions in science (in theUSA and Canada; in central Europe itis well below 15%), this situation willcontinue. You may not be able tochange the system, but you can pre-pare yourself before you enter it. Thisis why communications specialistPeggy A. Pritchard has compiled theessay collection Success Strategies forWomen in Science.

Pritchard argues that every youngscientist needs a mentor, a personhigher up on the career ladder who iswilling to share her experiences onhow to get ahead. As not all studentscan approach such a person directly,she selected a circle of successfulwomen scientists who give their per-sonal advice in this “portable men-tor”. In its 12 chapters, the reader isled through a wealth of informationconcerning professionalism that isusually not part of the science cur-riculum. ‘Communicating Science’ isone of the core chapters, in which stu-dents preparing their first talks canlearn how to convey confidence andwin over the audience. The more

experienced scientist is reminded tolearn at least the first few sentences ofher presentation by heart. Less formaloccasions, such as meeting colleagues,also benefit from preparation, andcommunication with the lay publiceither directly or via the media is bestdone using plenty of examples andmetaphors.

The chapter ‘Working Abroad’ givesyoung scientists good reasons forbroadening their horizons. Thedescription of ‘Networking’ will helpthose who feel pressurised by theneed to assemble a distinguishedportfolio of discoveries to understandthat teamwork is a win-win situation.An awareness of ‘Personal Style’ andgood interpersonal skills are impor-tant when you start ‘Climbing theLadder’. Manage your time and trainyour brain, recognize turning pointsand cope with setbacks, ask for indi-vidual work solutions when you havechildren – the reader learns muchmore from this book than just adviceon straight career building.

Unfortunately, this otherwise excel-lent book is marred by its openingchapters, which will especially puzzlescientists who are trained in carefulreading and clear thinking. Here thereader is confronted with three ratherredundant forewords. Next, Chapter 1concentrates too much on success asthe only goal of career managementwhile other parts of the book quitesensibly deal with the need for

‘Balancing Professional and PersonalLife’ and ‘Transitions’. Finally,Chapter 2 offers a very generaldescription of a certain gender-relatedtraining programme that was con-ducted in Germany between 2001 and2004.

My recommendation to readers istherefore to skip over the first 40pages to reach the wealth of practical,concisely written advice which isenlivened by short clippings of per-sonal biographies. References at theend of each chapter include easilyaccessible websites, and the bookends with a comprehensive index. Asfar as communication goes, the bookis the mentor.

Although aimed mainly at femaleadvanced science students, the wide-ranging advice on how to optimisejob performance makes the book ageneral guide to professional conduct.My personal favourite is the list of‘personal traits that help’: gain a repu-tation for integrity, work on a highenergy level, handle conflicts in a pos-itive, productive manner, guard yourlanguage and develop an appropriatepersonal style. It probably is a goodidea to start working on these issuesas early as possible, and although thebook has ‘women’ in its title, menshould read it, too.

Science teachers in schools areimportant role models. They may bethe first mentors for gifted pupils andtheir degree of professionalism has a

Success Strategies for Womenin Science: A Portable MentorBy Peggy A. Pritchard (editor)

Reviewed by Angelika Börsch-Haubold, Germany

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Reviews

great impact on adolescents who stillhave to decide where to go. Teacherswill profit directly from the chapterson communication skills, time man-agement and mental strength, andthey should pass on the informationto their students. In addition, girlswho are interested in studying scienceshould be encouraged to read thebiographical sections so that if theyare ever subtly informed of theirworker-bee status in the laboratoryhierarchy, they become neither angrynor discouraged.

DetailsPublisher: Elsevier Academic Press


ISBN: 0120884119


Superman, Batman, Lightning Lad,Spiderman – they all apply the princi-ples of physics to perform theirextraordinary feats... or do they?Which laws are suspended, and whichare extended? Which are indeed for-gotten completely? James Kakalios’sview is that many fundamental princi-ples of physics can be better under-stood by examining the activities ofsuperheroes in comic strips, somefamous and some not so well-known.As the foreword comments, “Comicbook heroes are fun, inclined planesaren’t”. Thus for teachers, this book isa fantastic resource of exampleswhich, at all levels, can enliven someof the more mundane areas of thephysics syllabus.

With sections on mechanics, energy(heat and light) and modern physics,students can be challenged to ques-tion the activities of superheroes,touching on many aspects of physics.All the heroes I have heard of, and afew more besides, are mentioned, anda good index allows the reader to con-sult entries on different heroes as wellas widely separate topics such asgravity and gamma rays, tempera-tures and tension. Kakalios does notlimit himself to the fantasy worldhowever, but attempts to relate eachtopic to the everyday real world ofmotor cars, microwaves and mole-cules, enhancing the reader’s under-standing.

As this is an American book, Ifound the use of pounds and feet,rather than consistent SI units, some-what frustrating, but the need for usEuropean teachers to “do the sumsourselves” may not be a bad thing.The book is illustrated with manyexamples from the comic strips them-selves, though these would have beenmore helpful in colour. Maybe atsome point in the future, the publish-ers would consider producing a seriesof colour slides for use in the class-room.

So if you have not yet read ThePhysics of Superheroes, I urge you tobuy a copy and enjoy the debate onwhy Superman was the “man ofsteel” and became the most unrealis-tic superhero of all, how Spiderman’sstrands have their limitations, andwhether he understood electromag-netism.

This is a book that every scienceteacher should read. It is the kind ofbook that can be taken on holiday,read over a long period or in shortdigestible chunks. Either way, I amsure that once read, some of its con-tents will be used over and overagain.

DetailsPublisher: Duckworth Press


ISBN: 0715635492

The Physics of Superheroes By James Kakalios

Reviewed by David Featonby, UK

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classroom, asking my students if theyknow ‘When a spider builds a webfrom tree to tree, how does it stringthe initial thread across a wide dis-tance?’ We had an interesting lessonabout spiders, food chains andecosystems as a result.

I can highly recommend RealMosquitoes Don’t Eat Meat to anyteacher who thinks it is often hard to answer difficult questions frompupils. But it is not just teachers who will benefit; this book is worthreading for everyone.

DetailsPublisher: WW Norton & Co


ISBN: 0393061574


I was examining a list of more than 20 books available for reviewingwhen I discovered this odd title. I amnot especially interested in mosqui-toes, and I know very little aboutthem. But a colleague’s encourage-ment and my own curiosity led me to choose this book from the list.

When I received the book, I startedreading at once and continued for therest of the evening.

What kept me so interested were all the quirky questions, such as: Doanimal have orgasms? Why are otherprimates so much stronger than us?What causes you to see stars after ahard blow to the head? Is it safe todrink out of plastic bottles? Whendogs sniff at each other, what are they smelling? Is it ever too cold tosnow?

The book comprises 168 questionsand answers, divided into four chap-ters. Chapter 1, The Great Beyond,contains questions about meteorology,astronomy and the Moon. The nextchapter answers questions about thebody. If you are more interested inour planet, Chapter 3 contains manyquestions and answers on this topic.The last chapter covers the Carbon

Factor: Life and Nothing but Life.All the questions and answers are

taken from the American magazineOutside, and are written by the authorof the magazine’s ‘Wild Life’ column– a space where readers’ questionsabout natural science and outdoorlore are answered. Some of theanswers, although only few, are notso relevant for European readers,because they are directly related toAmerica – for example, ‘What per-centage of the US is paved?’

All the answers are given byAmerican scientists, expert outdoors-men and professors. They are allexperts in their narrow fields, andtheir answers are easily understand-able by everyone. You don’t need tohave a degree in biology or astrono-my to enjoy reading this book.

Another big advantage with thisbook is that you don’t need to start onpage one and read the topics in order:jumping back and forth brings thereader to quite different themes andcrazy oddities on our earth. Andmany nice illustrations make readingeven more fascinating.

I have already used some of thefunny stories and explanations in my

Real Mosquitoes Don’t Eat Meat: This and OtherInquiries into the Oddities of Nature

By Brad Wetzler

Reviewed by Sølve Tegnér Stenmark, Malakoff Upper Secondary School, Moss, Norway

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Reviews


The goal of this DVD is to showhow information collected frompatients often allows scientists toachieve a deeper understanding ofthe genetic and molecular basis of aspecific disease. This level of under-standing is crucial to developingtreatments for disease and, conse-quently, to relieving patients’ suffer-ing.

The first of two DVDs contains fourcaptivating presentations from twoprominent investigators in the field ofbiomedical sciences, delivered at theHoward Hughes Medical Institute’sHoliday Lectures on Science inDecember 2003. The audience consist-ed of high-school students. In the firsttwo presentations, Bert Vogelstein(Johns Hopkins University School ofMedicine) explains the nature of can-cer, what causes it and how it can beprevented and treated. In the finaltwo presentations, Huda Y. Zoghbi(Baylor College of Medicine) presentsher discoveries on two neurologicaldisorders, spinocerebellar ataxia typeI and Rett syndrome.

The second DVD contains the ani-mations and video clips from the pre-sentations; biographies of Vogelstein,Zoghbi, and two graduate studentswho work in research labs; and a setof five special features – a bioethicsdiscussion with the active participa-tion of the students, informationabout the use of animals in research(transgenic mice), an interactive activ-ity that engages the viewer in pedi-gree analysis, and presentations on

two highly significant genetics topics,the proteins p53 and proteasome.

The main target group of this DVDset is biology teachers and upper sec-ondary-school students with an inter-est in the biological sciences and med-icine. However, after watching thesepresentations, anyone could beinspired to follow a career in thesefields. The viewer watches real-lifescientists talk about their investiga-tions to unravel the mysteries of dis-eases that could affect any one of us.The lectures are lively and interactive;they include excellent animationsabout the genetic, molecular and cel-lular mechanisms that cause the dis-eases as well as short video clips inwhich patients and their families talkabout their problems and hopes. Thestudent audience asks questions, pro-viding the opportunity to have com-mon questions answered by the spe-cialists.

The viewer not only acquires scien-tific information about the diseasesunder investigation and the efforts tocure them, but also learns what itmeans to work in a research lab.People often think of scientists aseccentric individuals who hide awayin their secret labs where they per-form strange experiments thatnobody understands. This impressionis obviously wrong and the materialin the DVDs does an excellent jobrevealing the truth about scientistsand their work. Conducting researchin a lab might mean a lot of hardwork, but these DVDs show that it

Learning from Patients: The Science of Medicine Reviewed by Michalis Hadjimarcou, University of Cyprus, Cyprus

could prove to be a rewarding andfun experience. The life of a scientistin the lab is not a solitary one;instead, it involves collaborationamong co-workers on a daily basisand even direct contact with patients.

In recent years, the world has expe-rienced spectacular advances in thefield of genetics and biomedical sci-ences. This progress has generated anumber of crucial ethical questions asto how to manage an individual’sgenetic information. The bioethics dis-cussion in the second DVD is veryinformative on this subject and couldeasily be used to promote similaractivities in the classroom.

DetailsPublisher: Howard Hughes Medical

Institute


OrderingThis and other DVDs can be ordered

free from the Howard HughesMedical Institute:www.hhmi.org/biointeractive/

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Resources on the web

Free science journals

Are you looking for a good article to use in a lesson? Or doyou just want to browse a science journal or two for inspira-tion? Here is a selection of free online science journals andsome useful tools for tracking down the books, articles andjournals you need.

Some free online journalsBlue Sci: www.bluesci.org

Blue Sci is a free online science magazine produced by stu-dents of the University of Cambridge, UK.

CBE-Life Sciences Education: www.lifescied.orgCBE-Life Sciences Education is a free, online, peer-reviewedjournal of science education, published by the AmericanSociety for Cell Biology.

Frontiers: http://192.171.198.135/frontiers/Frontiers is a free online journal of articles on research proj-ects in astronomy and particle physics funded by theParticle Physics and Astronomy Research Council, UK.

Nature: www.nature.comSome of the contents of the wide range of Nature journals,especially special articles and selected features from theNature Reviews journals (e.g. Nature Reviews Microbiologyand Nature Reviews Genetics) are free online.

New Journal of Physics: www.iop.org/EJ/journal/NJPThe New Journal of Physics is an open-access, online researchjournal covering the whole of physics, published by theInstitute of Physics, UK and the Deutsche PhysikalischeGesellschaft, Germany.

New Scientist: www.newscientist.comAlthough not all content in this popular science magazine isfree to non-subscribers, many of New Scientist’s latest arti-cles are.

PLOS Biology: www.plosbiology.orgPLoS Biology is a peer-reviewed, open-access journal pub-lished by the Public Library of Science (PLoS), a non-profitorganisation committed to making scientific and medicalliterature a public resource.

Plus magazine: http://plus.maths.orgPlus is a free online magazine which aims to introducereaders to the beauty and applications of mathematics.

Sci-Journal: www.sci-journal.orgSci-Journal is a free online journal which publishes the workof young scientists. The journal is based at the University ofSouthampton, UK.

Seed Magazine: www.seedmagazine.comSeed Magazine is popular science magazine; the freely avail-able website includes articles from the magazine as well asother regularly updated content.

The Scientist: www.the-scientist.comMuch of the recent content of The Scientist, which followsdevelopments in the life sciences, is free online.

Search toolsGoogle Scholar: http://scholar.google.com

Using the normal Google search engine, you can retrieve allsorts of information – some reliable, some less so. GoogleScholar allows you to have more confidence in your resultsby searching the scholarly literature across many disciplinesand sources: peer-reviewed papers, theses, books, abstractsand articles.

PubMed: www.pubmed.orgPubMed is used by researchers in the life sciences to scanthe scientific literature, and allows you to search by topic,author, or journal. The results list is linked to the articleabstracts; if the complete article is freely available or if youhave a subscription to the journal it is published in, you canlink to the article.

The amount of information can be dismaying, so trynarrowing the search by clicking on the ‘Limits’ tab to entera more specific search. For an introduction to a topic, select‘Reviews’ from the ‘Type of Article’ list; you then onlyretrieve articles that give an overview of your selectedtopic. You can also limit the search to articles that are freelyavailable (choose ‘Links to free full text’).

Digital Object Identifier (DOI): www.doi.orgMany published articles have a DOI, an online identifierthat remains unchanged even if, for example, the journalmoves to another publisher. The DOI website has a searchbox into which you can enter the DOI (e.g.10.1073/pnas.0500398102); this takes you straight to thepage for that article. If the journal is not free and you donot have a subscription, you will normally see the abstract.

The DOI website offers some other useful tools toinstall, such as a DOI button. Whenever you come across aDOI in an online text, you can highlight it and click on thebutton to jump straight to the article or abstract.

International Standard Book Number (ISBN): http://isbntools.com or www.amazon.comThe ISBN is used internationally to identify a particular edi-tion of a book. The ISBN (e.g. 0340831499) can provide avery useful shortcut to find other details of the book, suchas the title or authors.

To suggest types of websites that you would like us toreview, or to tell us about your own favourite websites,email [email protected]. In the subject field of theemail, please include the text ‘Website review’.

The worldwide web is a wonderful sourceof information, but the sheer amount ofcontent can be overwhelming. Where doyou start looking for science news? In eachissue of Science in School, we will suggestuseful websites for particular purposes.

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Putting the fizz into physics!Lucy Attwood from Oxford Danfysik, UK,explains the mysterious appeal of champagne.

Back in the staffroom

Champagne, champagne, cham-pagne. It has launched a thou-

sand ships, toasted countless examresults, witnessed millions of propos-als and, I’m pretty sure, initiated aninnumerable number of headaches!

People have celebrated withchampagne (the sparkling wineaccidentally discovered in theChampagne region of France) sincethe 17th century. Practically every-body I know loves it because of itsfabulous fizz, and most associate thebeverage’s quality with the size andquantity of its characteristic bubbles.

So where do the bubbles come from?

During the fermentation process ofwine manufacture, yeast reacts withgrape sugar to produce alcohol andcarbon dioxide gas. In standard wineproduction, the gas is released, butwhen producing sparkling wine, thegas is instead trapped under pressureinside the bottle. There it remains,dissolved in the liquid, until a suit-ably special occasion dictates that thecork should be ceremoniouslypopped.

Once open, the higher concentrationof carbon dioxide in the wine than inthe atmosphere results in an imbal-ance, which reaches equilibriumthrough the formation of bubbles;bubbles that escape from the liquiduntil balance is restored. Bubbles,

bubbles, bubbles – adding sparkle forthe eye and tingle for the tongue.

The bubbles don’t just form any-where, however; they are triggered atpoints in the glass or bottle wherethere is a microscopic defect such as ascratch or dust particle. The irregular-ity, known as a nucleation point,prompts carbon dioxide molecules tocome out of solution and create abubble. The bubble expands as moremolecules diffuse into it from thesurrounding liquid, which has amuch higher concentration of carbondioxide.

Once the bubble is big enough tohave acquired sufficient buoyancy, itdetaches from the nucleation pointand rises to the surface. Alone again,the irregularity grabs more carbondioxide molecules from the liquid andanother bubble is formed, and anoth-er, and so on until you have a steadystream of bubbles rising verticallythrough your drink.

So next time you’re at a party andsomebody hands you a rather expen-sive-looking flute of fizzy champagne,remember... it’s probably just a dirtyglass!

Try it at homeYou can easily demonstrate the for-

mation of bubbles at nucleation sitesusing salt. The surface of a salt grainis covered with microscopic flaws,which make perfect gathering

places for carbon dioxide molecules.Dropping a little salt into a glass ofchampagne creates hundreds of newnucleation sites, resulting in animpressive display of sparkle.

Important warning: using cham-pagne for this experiment is extreme-ly dangerous and could result insevere damage to the bank balance.Under no circumstances shouldchampagne be used for this demon-stration; instead, use beer or anothercarbonated beverage!

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Credits

Science in School is published by theEIROforum (a collaboration between sevenEuropean inter-governmental scientificresearch organisations: www.eiroforum.org)and is based at the European MolecularBiology Laboratory (EMBL: www.embl.org)in Heidelberg, Germany.

Science in School is a non-profit activity,part of the NUCLEUS project supported bythe European Union.

Disclaimer

Views and opinions expressed by authorsand advertisers are not necessarily those ofthe editor or publishers.

Subscriptions

Science in School is freely available onlineand print copies are being distributedacross Europe.

To receive an alert when each issue is pub-lished, send an email with the subject‘Subscribe to Science in School’ [email protected]. Include yourpostal address to receive a free print sub-scription (limited availability).

Copyright

With very few exceptions, articles inScience in School are published underCreative Commons copyright licences,under which the author allows others to re-use the material as specified by theappropriate license.

These articles will carry one of twocopyright licences:

1) Attribution Non-commercial Share Alike (by-nc-sa):

This license lets others remix, tweak, andbuild upon the author’s work non-commer-cially, as long as they credit the author andlicense their new creations under the iden-tical terms. Others can download and redis-tribute the author’s work, but they can alsotranslate, make remixes, and produce newstories based on the work. All new workbased on the author’s work will carry thesame license, so any derivatives will also benon-commercial in nature.

Furthermore, the author of the derivativework may not imply that the derivativework is endorsed or approved by the authorof the original work or by Science inSchool.

About Science in SchoolScience in School aims to promote inspiring science teaching by encouraging communication betweenteachers, scientists and everyone else involved in European science education.

Science in School addresses science teaching both across Europe and across disciplines: highlightingthe best in teaching and cutting-edge research. It covers not only biology, physics and chemistry, butalso maths, earth sciences, engineering and medicine, focusing on interdisciplinary work.

The contents include teaching materials; cutting-edge science; education projects; interviews withyoung scientists and inspiring teachers; education research; book reviews; and European events forteachers. An online discussion forum will enable direct communication across national and subjectboundaries.

Science in School is published quarterly and is freely available online; print copies are being distributedacross Europe. Online articles are published in many European languages; the print version is availablein English.

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2) Attribution Non-commercial No Derivatives (by-nc-nd)

This license is often called the ‘free adver-tising’ license because it allows others todownload the author’s works and sharethem with others as long as they mentionthe author and link back to the author, butthey can’t change them in any way or usethem commercially.

For further details, see http://creativecommons.org.

All articles in Science in School will carrythe relevant copyright logos (see above) or,where these do not apply, the appropriatecopyright notice will be appended.

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Published by the EIROforum: Supported by the European Union: Part of the NUCLEUS project:

In this Issue:

Highlighting the best in science teaching and research ISSN: 1818-0353

Summer 2006 Issue 2

Exoplanets

Using insects to fight crime

Uffe Gråe Jørgensen describes thesearch for Earth-like planets aroundother stars.

Also:

Forensic entomology

titel_SiS_Issue2.RZ 05.07.2006 14:23 Uhr Seite 1

in this issue: - exoplanets - eso.org

Documents