ED 320 780

TITLE

INSTITUTIONREPORT NOPUB DATENOTEAVAILABLE FROM

PUB TYPE

EDRS PRICEDESCRIPTORS

ABSTRACT

DOCUMENT RESUME

SE 051 527

Still More Science Activities. 20 Exciting ActivitiesTo Do!

Smithsonian Institution, Washington, D.C.ISBN-0-929648-01-389

158p.; For a related document, see SE 051 526.Galison Books, 36 West 44th Street, Room 910, NewYork, NY 10036 ($9.95).Guides - Classroom Use - Guides (For Teachers) (052)

MF01/PC07 Plus Postage.Biological Sciences; * Elementary School Science;Elementary Secondary Education; Intermediate Grades;*Laboratory Procedures; *Middle Schools; PhysicalSciences; *Science Activities; Science Education;Teaching Guides

Science and technology affect every facet of humanlife. By the 21st century, society will demand that all of itscitizens possess basic competencies in the fundamentals of scienceand the use of technology. As science increasingly becomes thedominant subject of the work place, it is important to begindeveloping within children an understanding and appreciation ofscience early in their lives. This book provides suggestions forinteractive science activities that can be done in a variety ofsettings, using inexpensive and readily available materials. Theactivities are designed as supplementary curricular materials andeducational guides for use in teaching science. Each of the 20activities in this book includes a list of materials, some backgroundinformation, procedures, and suggestions for variations. Topics inthis volume include stars; sund'.als; whistles; timers;chromatography; making a 3-D viewer; brine shrimp; making a bottlegreenhouse; science toys; tie dying; periscopes; earthworms; solarcookers; cylinders; kitchen botany; germs; making paper; bread;yogurt; and pinhole cameras. (CW)

* Reproductions supplied by EDRS are the best that can be made* from the original document.

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)).U S DEPARTMENT Of EDUCATION

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EDUCATIONAL RESOURCES INFORMATIONCENTER (ERIC)

IThis document has been reproduced asreceived from the person or organizationoriginating itMinor changes have been made to imprG.ereproductioi quality TO THE EDUCATIONAL RESOURCES

INFORMATION CENTER (ERIC."

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"PERMISSION TO REPRODUCE THISMATERIAL HAS BEEN GRANTED BY

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FROM THE SMITHSONIAN INSTITUTION

STILL MORE

I I I

GALISON BOOKSGMG PUBLISHING, NEW YORK

Copyright 1989 in all countnes of the International CopyrightUnion by the Smithsonian Institution All nghts reserved

A Galison Book

Published by GMG Publishing Corp25 W. 43rd StreetNew )bric, NY 10036

ISBN 0-92964841-3

Authors Megan Stine, Craig Gillespie, Gladys Stanbury,laune Greenberg, Jame Harms, Sharon Mayes,Larry Malone, Carol Moroz-HenryReviewer Kathy Faggella

Designer. Manlyn Rose

Design Assistant Chnstine KirkIllustrator Simms TabackEditor Cheryl Solimini

Production Editor Cat .enne GrandsardPublisher Gerald Galison

a

CONTENTSIntroduction 7

Star Tracking 11

Turf Tickers 15Whistles and Flutes 19Time Out 23Hidden Rainbows 273-D Viewer 31

Briny Behavior 35Garden in a Glass 39Toying with Science 43Bleach Blues 47Good Looker 51

Slime Time 55Solar Cooker 59Super Straws 63Kitchen Botany 67Aliens 71

Lawn Paper 75Serious Loafing 79Yummy Yogurt 83Camera Creations 87

:J)5

INTRODUCTION

Science and technology torches nearly every facet of our lives today. By the 21st century, oursociety will demand that all its citizens possess basic competerr'es in the fundamentals ofscience and the. use of technology. As science increasingly becomes the dominant subject of

the work place, it is important to begin developing within children an understanding andappreciation of science early in their lives.

Learning can, and does, occur in many places and many situations. Learning occurs in school, athome, and on the trip between home and school. This book provides suggestions for interactivescience activities that can be done in a variety of settings, using inexpensive and readily availablematerials. Whether the activities are done in a classroom or in a home, they will provide adults anchildren with increased opportunities to explore natural phenomenon in an engaging and excitingway. Included are experiments, activities, crafts, and games that allow you, whether teacher orparent, to learn science along with your children. The only requirements for success are thedirections provided with each activity, a few common household items, a little bit of time, andsome curiosity and imagination. The activities in this book are designed as curricular materials,educational guides for you to use in teaching science.

SOME SUGGESTIONS FOR TEACHERS

The activities in this book should be used as supplements to your normal classroom sciencecurricula. Since they were originally developed for use in out-of-school situations, they mayrequire some minor modifications to permit a larger number of children to participate.

Nonetheless, you will find that these activities lend themselves well to a fun-filled science lessonfor all participants.

An increasing number of school distracts are exploring the use of "take-home" lessons in order tobuild stronger learning partnership bonds between parents and teachers, home and school. Thesematerials have proven to be an excellent source for such "team-building" efforts. Both teachers andparents find these activities rewarding ways to provide quality learning experiences for children.

SOME SUGGESTIONS FOR PARENTS

0ne of the most important jobs that you have, as a parent, is the education of your children.Every day is filled with opportunities for you to actively participate in your child's learning.Together you can explore the natural world and make connections between classroom

lessons and real-life situations. You will learn the value of asking good questions, as well as strategiesfor finding answers to those questions.

FOR BOTH TEACHERS AND PARENTSThe best things you can bring to each activity are your experience, your interest, and, mostimportantly, your enthusiasm. These materials were designed to be both educational andenjoyable. They offer opportunities for discovery, creative thinking, and fun.

HOW TO USE THIS BOOKThe science activities in this book can be successfully implemented by any interested adult,regardless of his or her science background. A.ccordingly, the above have been designed sothere is no one "correct" solution and no "right" way to do it. Do not be afraid to say "I don't

know!"There are twenty activities in this book; since every classroom and family is different, not all

activities will be equally suitable. Take the time to browse through the book and find the ones thatseem to make sense for your class or family There is no prescribed orderto t.lese activities, nor anynecessity to do all of them. Once you have selected an activity to do, take the time to read through itbefore you attempt to do it.

At the beginning of each activity is a list of all the materials you will need to do the project. Try toassemble all of these items before you begin. The procedures have been laid out in an easy-to-follow, step-by-step guide. If you follow these directions, you should have no difficulty doing theactivity. Once you have completed the basic activity, there are also suggested variations that youcan try, now or later. At the end of each activity is an 'Afterwords" section. This section is for you, theadult. It is intended to provide additional information, not on how to help children but for theinteres of an adult participanttake some time to read it for your own enjoyment.

ASKING QUESTIONSEncourage your children to ask qi iestions, even if you don't know the answers. The essence ofscience is asking questions, and then trying to find out the answers. Some of the answers canbe discovered in books, some through observation, and some, at present, are unanswerable

by anyone. Ask questions like:(before you start)"What do you think is going to happen when we do this experiment?"(during the activity)"What do you see?""Does this remind you of anything else you've ever seen?"(after the activity is completed)"What do you know about X now, that you didn't know before we started?"

118

"Is there anything you don't understand? How can we find out the answer ?"Encourage all kinds of answers, and all kinds of questions. Sometimes the crazy ones are the ones

that work. Often there is more than one answer to a question, ' D be tolerant of diversity and open tomultiple solutions. Use the library or an encyclopedia to help answer questions and further yourunderstanding. Lead, or have a child lead, a discussion after the project is completed. This will helpto pull together what happened, why things happened, and what the activity was all about. Justremember that it may take more than one exposure for some of the ideas introduced in theseactivities to "sink in." These activities are beginnings, not endings. Finally, don't be afraid to be aleamer yourselfthat was a large part of why these activities were developed in the first place.They are for learning, adults and children together.

John H. Falk, Ph D.

PresidentScience Learning, Inc.

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STAR 111 C INJBe different! Look at the starsin the daytime, instead of atnight. With these experiments,you can put on your own lightshow, make a delicious break-

fast, and learn how to identifysome constellations at thesame time!

A sky full of twinkling stars is awonderful thing to watch. Butmost people agree that it'shard to find the constellationsin the night sky. Part of theproblem is that constellationsdon't look anything like thenames given to them. Sagitta-

rius, for instance, is supposedto be an archer; but, as youcan see on the star map, Sagit-tarius looks more like a teakettle with a triangular spout.And to make it even harder,there aren't any lines drawn inthe sky to point out the shape!

Once you become familiarwith their patterns, though,

the constellations will be easierto spot. Try picking out the

patterns in these star-studdedpancakes, and then go onto make your own super-starlight show. By the time youfinish these experiments, yourstar-gazing skills will besuper-sharp!

EXPERIMENT No.1STELLAR PANCAKES

Learn to recognize Sagittariusin a blueberry pancake, andyou'll have no trouble huntingdown the archer in the nightsky! You'll need about 60 min-utes to make and eat the pan-cakes and talk about the stars.

YOU WILL NEED

Pancake mix, or preparerecipe at right

1 Cup fresh blueberries,or raisins

Griddle or frying panStoveMap of the night sky

(on inside back coverof this book)

Spatula

1Make the pancakebatter, using a box mixor the recipe below .

Have ready 1 cup of washedblueberries or 1 cup of raisins.While you are making thebatter, let the other peoplein your family look at themap of the night sky.

PANCAKE RECIPE

1 Egg

11/4 Cups milk

3 Tablespoons melted butter11/2 Cups flour

11/2 Teaspoons baking powder1/2 Teaspoon salt

2 Tablespoons sugar

Beat egg. Add milk and butter.Stir in flour, baking powder,salt, and sugar; mix until thebatter is almost smooth.

Yield: Makes 10 eight- to10-inch pancakes.

Grease a griddle or fry-ing pan (or use one witha non stick coating).

Heat it on the stove until adrop of water skips acrossthe surface. Now you knowthe pan is hot enough.

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3Pour enough batteronto the griddle tomake an 8- to 10-inch

pancake. Then choose oneconstellation from the mapof the night sky. Arrange blue-berries or raisins in the pan-cake to resemble the patternof the stars in that constellation.

4When bubbles appearon top of pancake, usea spatula to turn the

pancake over. Cook the otherside until golden brown.

5Continue making pan-cakes, using a differentconstellation for each

one, until you have one ortwo pancakes for each personin your family. Then serve thepancakes and put the map ofthe night sky in the center ofthe table. Each person shouldty to identify the constellationin his or her pancake beforeeating it!

EXPERIMENT No. 2 --STARS ON THE CEILING

Here's another great wayto practice identifying the

constellations, one at a time.In about 30 minutes, you canmake your own privateplanetarium.

YOU WILL NEED

Empty round oatmeal buxScissors, tape, rulerFlashlight

CardboardMap of the night skyPencil

1 Nail

Red cellophane

....MUM..

1Cut a small hole in

the bottom end ofan empty oatmeal box

and put a flashlight throughthe hole, taping around theedger to hold the flashlightin place. Remove the box lidand cut a circular hole in it,leaving a 1/2" rim all around.

2Use cardboard or verythick paper to cut outseveral disks that are

the same size as the outsidedimension of the oatmealbox lid. These disks will be

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the "slides" you'll put on theoatmeal box, which is your"constellation projector.'

3Using the star mapas a guide, draw oneconstellation on each

of the cardboard disks. Makenail holes where each star inthe constellation appears.

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4Now put the lid backon the oatmeal boxand point the flashlight

upward. Turn out the lights,and take turns projecting yourconstellations on the ceilingby placing your disks on topof the cutout lid. The flashlightwill shine through the nailholes you've made, and thedots of light will form theshape of the constellation onthe ceiling. You may want tomake a game out of this, bysaying that the first person

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to identify your constellationcorrectly takes over the oat-meal box and gets to projecthis or her favorite constellationnext.

STAR-GAZING STRATEGY

Now that you've had somepoctice identifying the con-stellations, you're ready togo outside to gaze at thestar-studded sky.

Sit or he down. You'll getbored and tired if you stand.

Remember that the patternsyou're looking for are muchlarger in the sky than theywere on the pancakes oron your ceiling.

Cover the end of a flashlightwith red cellophane, and usethis to look at the star mapwhen you're outside. Becauseof the cellophane, your eyeswon't have to constantlyadjust from a bright light tothe dark of the night sky.

Be patient. Your eyes willadjust to the dark in 5 or 6minutes, but your night visionwill continue to improve. In 30to 45 minutes, you'll be ableto see even more stars thanyou could after only 5 minutes.The longer you watch the sky,the more stars you'll see.

AFTERWORDS

Look at the constellationsat different times of the night.You'll notice that some of themseem to move across the sky,"rising" and "setting" like thesun. Actually, the Earth's rota-tion is responsible for this illu-sion. As the Earth spins, starsthat were below the horizonat the beginning of the eveningcome into view a few hourslater. However, one starPolaris, the North Starremains in the same spot allnight, and the constellationssurrounding it are always visi-ble. That's because Polaris isdirectly above the North Pole.You can easily find Polaris:If you can spot the Big Dipper,the two stars along the outeredge of Big Dipper's "bowl"point to it. (See the star map.)

Another change inthe night sky results from theEarth's other movementits revolution around the sun.In summer, certain constella-

tions that earlier this yearwere above the horizon onlyduring the daylight hours arenow above the horizon atnight. For instance, Leo the Lioncan be seen in the evening allsummer; but by the end ofAugust, Leo will have droppedout of sight. At about the

same time, Pegasus will be-come visble in the eveningfor the first time this year.

Although we don't usuallythink of it as a star, the nearest

star to the Earth is actually thesun. If we could look at thesun from billions of miles away,it would look just like theother stars overhead. It wouldno longer be the brightest starin the sky, but it wouldn'tbe the dimmest one either.

After the sun, the nextclosest star to the Earth isnamed Alpha Centauri. It is4.3 light-years away, whichmeans that if we could travel186,000 miles per secondwhich is the speed of lightit would still take us 4.3 yearsto get there! Even though it'snearby, Alpha Centauri isn'tbright enough to be seen.The nearest star we can seeis Sirius, located in the constel-lation Canis Major. Sirius is

the brightest star in the sky.It becomes visible again inDecember.

One of the most beautifuland brightest objects in thesky, known as the eveningstar," isn't really a star at all. It'sVenus, the wandering planet,and you can find it in July inthe west just after sunset, orin the east just before sunrise.

19

Other planets may also bevisible to the naked eye, if youknow where to look. Marscan be found in Sagittariusand Jupiter should bevisble somewhere be-tween Pisces and Aquarius.The trick to finding them isto become familiar with theconstellations, so that you'llknow when there's an extra"star" stuck in there where itshouldn't be. Remember thatthe planets look just like starsexcept that Mars and Jupiterare not as bright as some stars

are. Also, planets don't twinkle.Although we can see

between 2,000 and 3,000 indi-vidual stars, that's nothingcompared with the 100,000stars in our galaxy, the MilkyWay. Most of those stars aretoo far away to be seen with-out a telescope. They all seemto blend together into a mistyband, which, in July, runsthrough the constellations ofCassiopeia, Cygnus, and Scor-pius. And this blend of stars isonly one galaxy one littleneighborhood among theuniverse of maybe 2,500galaxies or more.

14

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TURF TIC ERS"A clock the time may

wrongly tell;I, never, if the sunshine well:'

Rain or shine, it will take

several hours to build aTurf Ticker sundial.

YOU WILL NEED

Corrugated cardboard froma carton

ScissorsPencil

ProtractorRuler or yardstickMasking tapeCompass (optional)

There is an ancient, automatictimekeeper on your lawnevery sunny day. Learn howto use it by building a TurfTicker sundial. You can makethis simple sundial with onlya few parts. The sun shinesonto the pointer or gnomon(NO-mon) of the sundial. Thegnomon's shadow falls ontothe dial plate. The dial platehas numbers on it (like a clock)that tell you the time.

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Sundials have beenused to tell time for centuries.People all over the world havedesigned different kinds ofsundials. Even today, no formalgarden is complete withoutone. Now you can createyour own sundial, too.

diCut a piece of card-

board from a carton12 "x12" or bigger

the bigger, the better. Fold thecardboard in half. You maywant to score the fold slightly,so that it bends easily. Scoringmeans cutting the cardboardpartway through with thepoint of a scissors, so it'seasier to bend.

2 Using scissors, poke ahole in the top centerof your dial plate about

3/4" from the top edge. Makethe hole just large enough tofit a pencil into it. This is yourgnomon hole.

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3A protractor measuresdegrees of angles andcircles like a ruler meas-

ures inches or straight lines.

Find the small hole along thestraight edge of your protrac-tor. Lay the protractor ontop of the dial plate with thestraight edges parallel. Makesure the protractor's hole isright over the gnomon hole.

To label the dial plate,make a dot every 15 degrees

enforioN-HocE

all the way around the pro-tractor. Start at 0 degree`then mark 30 degrees, 45degrees, 60 degrees, andso on. Remove the protractor.

4 Using a ruler, draw linesfrom the gnomon holeto each of the dots.

These are your hour lines.Label each hour line, startingat 6 A.M. on one side andgoing all the way around thesemi-circle to 6 P.M. The linethat goes straight up the mid-dle, at 90 degrees, is 12 noon.

5Make two triangles ofcardboard to prop upthe sundial at the cor-

rect angle for your latitude.For the sundial to work prop-erly, the triangles must bemade according to the instruc-tions. See the map to decidewhich city is on approximatelythe same latitude as yourhometown. For instance, ifyou liveig Seattle or Minnea-polis, use the dimensionsshown for Bangor, Maine.

2':

TRIANGLE INSTRUCTIONS

Make two right triangles. Righttriangles are ones that have anL-shaped side, forming a 90-degree angle. The length ofthe sides will vary, dependingon where you live. See dimen-sions at right. You will noticethat when you change the

length of the L sides, it changesthe other angles. You canmeasure the angles with yourprotractor if you want to.

Attach the trianglewedges with tape to hold thedial plate open at the correctangle. The bottom of the Lshould be touching the bot-tom or base of the sundial.

The side of the right tri-angle that is opposite the L

is called the hypotenuse.The hypotenuse should betouching the dial plate.

Triangle DimensionsSideof L

Bottomof L

Bangor, Maine: 51/4"

Washington, D.C.: 41/4"

Miami, Florida: 2"

51/4"53/8"

41/4"

§Put the eraser end ofthe pencil in place in`..he gnomon hole. The

pencil is now the gnomon.It should be set perpendicularto the dial plate. If you setthe protractor flat on the dialplate, the pencil should lineup with the 90-degree line.

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IFind a sunny outdoorspot for your sundial.Find north with a com-

pass and point your 12 noonline directly north. Or placethe sundial so that the gnomoncasts a shadow on the correcthour. Your noon line will befacing north.

2:17

KEEPING TIME

In the spring and summer, youmay be on daylight savingtime, but the sun and yoursundial are not. That meansthat your sundial will read11 a.m. when your watchreads 12 noon. When yougo back to standard time,your watch and sundialwill agree again.

So make sure the houryou set your sundial with isstandard time, not daylightsaving time.

VARIATIONS

To weatherize your sundial,cover the parts with plasticwrap or clear contact paper.

Use your cardboard partsas a pattern to make a sundialout of wood. With a fewlayers of shellac, it will bewaterproof.

2;;

AFTERWORDS

Every day, plant and animalactivities repeat themselves asif they were on a schedule.Leaves fold up at night, birdssing at dawn, and we arehungry at noon. Less obvious,but equally regular, photosyn-thesis, cell division, and hor-monal changes form dailypatterns. These and the manyother plant and animal activi-ties that occur at approxi-mately 24-hour intervals oper-ate according to "circadianrhythms:' Circadian comesfrom the Latin word circameaning "about" and diesmeaning "day'

Plants, insects, fish, birds,and humans all exhibit circa-dian rhythms. To find outmore about the biologicalmechanism that causes circa-dian rhythms, scientists havelowered plants and animalsinto salt mines, shipped themto the South Pole and spunthem on turntables, and or-bited them in satellites. Asa result of these efforts, mostscientists agree that plants andanimals have internal timingdevices called "biologicalclocks:' The chemical and

physical nature of theseclocks is not yet known.

Not every biological clockis set exactly for a 24-hourcycle. Some are as short as 21hours and others as long as 27hours. This difference can cre-ate problems. An insect witha 23-hour 25-minute rhythmwill be five hours behind aplant with a strict 24-hourschedule in only 20 days. Thismay be just long enough forthe insect to miss the fewhours of the day when theplant's flower is open.

Fortunately, the environ-ment helps synchronize thesedifferent rhythms. Many plantsand animals respond to slightchanges in the amount of day-light. For example, "long day"plants will only flower whenthere are many hours of day-light. Spinach will not grow inthe tropics, because it needsat least 14 hours of light eachday for two weeks, whichnever happens in the tropics.On the other hand, ragweeddoesn't grow in northernMaine because it only flowerswhen there are less than 141/2

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hours of daylight. The daysdon't shorten that much innorthern Maine until August,but then there isn't enoughtime for the seeds to developbefore the first frost.

We, too, depend on lightchanges to set our biologicalclocks. The effects of "jet lag"are, in part, due to the differ-ent rates at which the differentorgans and functions of thehuman body adjust to newschedules. One gland maysend a hormone to an organthat hasn't yet adjusted andisn't expecting any stimulus.Repeated jolts such as thesemay cause serious long-termeffects. Similarly, a prescrbeddose of mec .tine may causedifferent reactions at differenttimes of day. A dose that willhelp in the morning may harmat night. The more we learnabout circadian rhythms andbiological clocks, the betterwe can understand reactions,adaptions, and evolution.

18

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niYou don't have to be able tosing to make beautiful music.All you need is about 45 min-utes to set up this activity,

a steady hand, a slide whistle,and a lungful of air. Get ready...get set... BLOW!

YOU WILL NEED

Coping saw or small tubingcutter (see Note)

1 Length of 1/2" diameter

copper tubing (see Note)Ruler

Pencil

Fine sandpaper1 Dowel, 7" long with a

diameter large enoughto fit snugly inside thecopper tubing

HammerNail

Pliers

Cloth tape or masking tapeVarious empty soda bottlesNote: Inexpensive coppertubing and tubing cutter canbe easily obtained from a do-it-yourself home-improvementcenter or from some hardwlrestores.

2

AN FLUTESDid you ever wish you couldplay a slide trombone? Howabout trying out the next bestthing: the slide whistle? Justlike a trombone, a slide whistlecomes complete with all thenotes on the musical scale atyour fingertips.

SLIDE WHISTLE

..11Cut an 8" length of cop-

per tubing, using thecoping saw Or follow

the directions on the tubingcutter and use it to cutthe pipe.

2Place a piece of finesandpaper on the floor,rough-side up. Rub the

cut ends of the copper tubeback and forth over the sand-paper to sand the "burrs',' orrough edges, off. This is thebest way to sand, because itkeeps the ends of the tubeflat. Flat ends will produce the

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best whistle and flute sounds.Use another piece of sand-paper to smooth the outsideand inside edges of the tube,so that you can put yourmouth up to the pipe withouthurting yourself. Now try it.Can you blow across the topof the pipe and make a sound?Put your thumb or palm onthe bottom of the pipe tocompletely close the bottomhole and try again. Pract.ceblowing until you get a clear,strong tone.

2

3Sand the ends of thewooden dowel if theyare rough. Then ham-

mer a nail partway into theend of the dowel. Use pliersto bend the nail into a hookshape. The bent nail is yourhandle for the slide part ofthe whistle.

4Insert the dowel intothe copper tube andblow, while moving

the slide up and down. If youdon't get a clear tone, it isbecause the dowel doesn't fittightly enough. Remove thedowel and wrap it with a layerof cloth tape or masking tape.Try it again. Keep adding lay-ers of tape until the dowel fitssnugly enough to close thetube completely. At first youmight not have enough tape,and then you might have t.,$)much. But keep trying unti!the fit is right. Car; you playa scale by stopping the slidein various positions?

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WARM UP YOUR WHISTLE

The best warm-up for slide-whistle blowing is the alwayspopular "soda bottle full ofwater" trick. Gather up fouror five empty soda bottles.(Plastic ones are okay.) Addsome water to the first oneso that it is about 1/4 lull, fill thesecond bottle 1/2 full, and soon. Each bottle should have adifferent amount of water in it.

To blow, pull your lipsin tightly against your teeth sothat both lips are kind of flat.Your top lip should stick outjust a tiny bit farther than yourbottom lip. Hold the mouth ofthe bottle firmly against yourlower lip, and blow across the

opening not into it! Try tomake some of your breath hitthe far inside edge of the bot-tle mouth, while most of yourbreath glides out acrossthe top.

What makes the bottlewith the most water giveyou the highest tone? Is it thewater, the size of the bottle,the size of the bottle openingor something else? For the

FILI. EACH SODA BOTTLE WITH A DIFFERENTAMOUNT OF WATER-

answer, try experimentingwith different-size bottles,each filled with exactly 3 inchesof water. (Or, if you can't fig-ure it out, check out the infor-mation in the Afterwords!)

AFTERWORDS

If you've ever plucked a guitarand watched the strings goboinnnng, or put your handon a drum while it was beingplayed, or stood close enoughto a gong to feel the sound hityour chestyou know thatvibrations make sounds. Butwhat's the difference betweenordinary sounds and music?The answer is that the vibra-tions in music are very regularand even. The vibrations thatcreate nonmusical soundsare not.

Here's one way to showyourself the difference be-tween musical sounds andnonmusical sounds. First singthe word "hair" in any noteand hold it for 10 seconds.Now try to say the word "hair"very evenly, and take 10 sec-onds to do it. But here's thecatch: Don't let your voice goup or down. You must speak,not sing, the word withoutletting your voice change itstone at all. You'll find that itcan't be done! If you reallykeep your speaking voice thatsteady and even, it turns intosinging!

So the difference betweentalking and singing has to dowith the steady regular vibra-tions of your vocal cords. Butwhat vibrates in a slide whistleor flute? Is it the metal itself?No. The sound you hear whenyou play your slide whistlecomes from the column of airinside the tube. As your breathhits the inside edge oppositeyour lip, it starts the columnof air vibrating.

You can test this by mak-ing two single pipes: one ofplastic and one of metal orrubber hose. If they are boththe same length, they will bothproduce the same notealthough one may have a mel-lower sound and the othermay have a shrill quality.

Modem-day flutes, ofcourse, are just one long pipewith all the notes in the scale.To play a low note, the fluteplayer must cover all the holes,so that the column of air isvery long. To shorten the col-umn of air, the flute playersimply opens one of the holes.That lets the air "escape"sooner than it would havein the longer pipe.

Believe it or not the flute'sclosest relative is the organ. Infact, an early flute called a pan-pipe is said to have insnired

the invention of a water organin the third century B.C.Organs make music when airis forced across the openingsof pipes; so technically thatmakes them wind instruments.But if you've ever seen thesize of the pipes on an organ,you'll be glad you don't haveto blow into them to makethem play!

All musical instrumentsmake music using the same

principles. To produce a note,something must vibrate andthe shorter it is, the higher thenote. A piano has short stringsfor high notes and long stringsfor low notes. But violins haveonly four strings and they allseem to be the same length.How do you get high noteson a violin? The musicianshortens the string or reallyshortens the length a stringcan vibrate by holding thestring tightly against the neckof the violin with his or herfingers.

If you've ever wonderedhow the air in a trumpet canbe made shorter or longer,just look at all those twists andturns in the tubing. The valveson a trumpet open and close

certain sections of tubing tochange the overall length. Ona slide trombone, you can seehow the tubing is made longer.Just like on your slide whistle,the slide moves in and out tochange the length of the col-umn of air. On trumpets andtrombones, something elsevibrates too: the player's lips!

3,7:

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TI 1 OUTGot a minute? Greatbutyou'll need more than thatto make the timekeepersin this timely aciivity. Allowabout 15 minutes to set upeach "clock"and then planto watch them (excusethe pun) for an hour or so!

YOU WILL NEED

An 8" piece of cotton stringVegetable oilHeavy-duty aluminum foil or

pie panMatchesA watch or stopwatch2 Identical straight-sided

candles (not tapers)Candlesticks (or Plasticine, or

modeling clay, to holdcandles upright)

Small nailEmpty milk cartonBallpoint pen5 Identical paper or

Styrofoam cupsLarge cardboard boxBrass paper fasteners (with a

head and two prongs)Empty jar2 Small plastic soda bottlesHeavy-duty tapeBox of table salt

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When the ref calls "Timeout!"how does he knowwhen to call "Time in?" Heuses his stopwatch, ofcourse. These days we havelots of timekeepersfromdigital watches to Big Ben,London's famous clocktower. But in ancient times,finding ways to measure timewas a problem. How coulda peasant bake bread if hedidn't know how long toleave it in the oven? Here aresome clocks, timers, andstopwatches that were useda long, long time ago. Makethem all and then compare:Which clock is the most ac-curate? Which one wouldyou use if you really wantedco be on time?

A String TimerCut a piece of cotton string8" long. Knot the string atevery inch, trying to keep thespaces between the knotsequal. Pour a small amountof vegetable oil in a smalldish and soak the string inthe ail. Lay the oily string onan aluminum pie pan or on a

piece of heavy-duty alumi-num foil with the edgesturned up. Place the alumi-num pan in the kitchen sinkfor safety.

Have an adult help withthe next step. Light one endof the string and let it bumon the aluminum pan. Makesure the aluminum pan islying flator with thelighted end of the stringslightly uphill. Otherwise thestring won't burn evenly.

How long does it takefor the string to bum fromone knot to the next? Time itwith (2 watch or stopwatch.How long does an 8" stringbum?

A Candle Timer

Place two identical straight-sided candles in candle-sticks. Or set them side byside on an aluminum pie pan

3C,

and hold the candles inplace with small blobs ofPlasticine or modeling clay.Ask an adult's help to lightone of the candle? Be sureto keep your hat, andclothing away from theflame. Let the candle bumfor exactly 10 minutes. Blowout the flame. How far has itburned? Hold the first can-dle next to the other one.Use a nail to scratch a ringaround the other candle toshow how far down it willburn in 10 minutes. Continuescratching rings, equallyspaced, around the candles.Each mark represents 10 min-utes. Light one of the candlesagain and burn three sec-tions. Time the Candle Timer.How accurate was it? Didthe three 10-minute sectionsbum for 30 minutes? Whichclock is more accurate: theString Timer or the CandleTimer?

A Water Timer

Open up the top of anempty milk carton and rinseit. Use a ballpoint pen to

24

mark equally spaced lines onthe inside of the carton. Pokea small hole in the side ofthe carton, about an inchfrom the bottom.

Fill the carton with waterand let the water run out thehole into the sink. How longdoes it take for the water to30 down from the top line

USE A BALI. PoiNT PENTO MARK EQUALLYSPACEDUNE3 ON THEINSIDE OF CARTON

to the next line? Is the emp-tying time between each linethe same? Or does the waterempty more slowly as itdrains? Is this an accu-rate clock?

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A Deluxe Water TimerPoke one hole in the bottomof each of 5 identical paperor Styrofoam cups. Fastenthe cups in a row, one abovethe other, to the outside of acardboard box. To fastenthem, use brass paper fas-teners poked through thecups and the box. Weightthe inside of the box withrocks or books, so it won'ttip over Put an empty jarunder the bottom cup tocatch the water.

Measure out one full cupof water and pour it into tl'etop cup How long does ittake the water to run througheach cup? How long to

reach the bottom? Repeatthe experiment and time itcarefully. Is the Deluxe WaterTimer more accurate or lessaccurate than the otherclocks you have made?

An Hourglassor a3-Minute Timer?

Wash and completely drythe insides of two small plas-tic soft-drink bottles. (The16-ounce size works best.)Remove both caps and useheavy-duty tape to tapethem together with their topsides touching. Use a nail topoke a small hole straightthrough both bottle caps. Fillone bottle three-fourths fullof ordinary table salt. Screwon the double lid. Turn theother bottie upside downon top of the one filled withsalt. Screw it to the doublecap. To start your timer, sim-ply turn it over and watchthe salt run from the topbottle to the bottom. Howlong does it take? You mightwant to adjust the amount ofsalt in the timer so that ittakes exactly 3 minutes forthe salt to run out.

Which of the clocks thatyou made is the most relia-ble and accurate?

AFTERWORDS

What's the biggest clock inthe world? According to theGuinness Book of World Re-cords, you have your choice.The biggest clock facethefloral clock in Hokkaido,Japanis more than 59feet in diameter. The mostmassive clock is located inthe Cathedral of St. Pierre inBeauvais, France. And thelargest four-faced clock, witheach face 40 feet in diame-ter, is on the building of theAllen-Bradley Co. in Mil-waukee, Wisconsin.

But hold on a second ..

and look down. You're actu-ally standing on the biggesttimekeeper known to man.Earth, as it goes around thesun, is the "clock" that tellsus when it's day or night,when it's summer, winter,spring, or fall. All of the otherclocks and timepieces weuse are designed to mea-sureand to put a name ora number onthe chunks oftime we experience. But forcenturies, people had nobetter way to tell time thanto look up at the position ofthe sun in the sky But it's notso easy to measure outsmaller segments of timelike an hourby simply

looking up. That's why peo-ple invented clocks.

Perhaps the oldest clockknown is the sundial, whichwas invented more than4,000 years ago. Water andcandle clocks too, while notas ancient as the sundial, arevery early clocks The Greeksused water clocks calledclepsydras, which means"thief of water," to timespeeches made by lawyersduring trials. Judges wantedto be sure that each lawyerwas given the same amountof time to plead a case.Another timekeeper ..sedthe courts was the hourglassfull of sand. Each person wasallowed to speak until thesand (time) ran out from theupper chamber into thelower chamberthus theexpression "time is runningout"!

One of the biggest ad-vances in the measurementof time started in a church in1581. Seventeen-year-oldGalileo Galilei becamebored with the church ser-vice and started watchingthe swinging lights hangingoverhead. He noticed thatno matter how far the lightsswung, they always seemedto take the same amount of

40

time to complete a swing.He used his own pulse totime the swings. Galileofigured that anything thatmoved in such a regular waycould probably be used tomeasure time. Later on, pen-dulum clocks were invented.These clocks use a weightthat falls slowly to give smallpulses of energy to eachswing. However, a swingingweight in a clock is of no useto a ship tossing at sea. So in1761, John Harrison inventeda wind-up clock that wasaccurate.

Today, we have manyvery accurate timekeepersso your candle clock is ratherout of date. Quartz-crystaltimepieces, which wereinvented in the 1920s, areaccurate to within /Moo ofa second each 6 months.Atomic clocks, invented inthe 1950s, are even moreaccurate In fact, the world'sma. accurate clock is anatomic clock in the U.S.Naval Research Laboratory inWashington, D.C. It wouldtake 1.7 million years for thisclock to gain or lose onesecond! By the way, whattime is it?

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Beautiful sunsets, forest

scenes, and colorful rainbowscan be found hiding deep inthe stroke of your pen. HowdD you release them for yourviewing pleasure? The secretis a technique called paperchromatography and will takeyou less than an hour todiscover.

YOU WILL NEED

1 Package of coffee filtersScissors

Several rubber bands1 Dishpan, large bowl, or

other basin at least4" deep

Tape

1 Set of colored marking pens,water soluble

Old newspaper1 Set of liquid food colorings,

small sizePaper platesToothpicks

1 Package of M&M candies

Deep-colored fruits andvegetables

Vinegar or rubbing alcohol

42

EN RAIN 0 S1

Cut a bunch of stripsof filter paper about3/4" wide and 4" long.

Then cut 2 or 3 rubber bands,stretch them iicross the basin,and tape them in place. Foldone of the paper strips over1/2" at the end, and hang it onone of the rubber bands. Putjust enough water into thebasin to bring the water upto the end of the paper.

2Select a pen from yourset. Use it to draw aline across the width

of one of the paper strips, 1/2"

from the bottom. Fold the topof the strip over '' and hangit on the rubber band. Watchthe water wick up the paper,doing its magic on the inkmark as it moves upward.

3Try all of the colorsyou can find. Blacks,browns, and dark

greens are particularly inter-esting. Try to find a number

of different brands of pens inthese dark colors. When thecolors have moved as far

up the paper as they can(in about 5 minutes), lay themon old newspaper to dry.

VARIATIONS

Use your chromatographyset-up to find out how foodcolorings move. Mx drops offood colors on a paper plateto make your own inks, andsee if the original colors canbe separated out. Use tooth-picks to mix the drops ofcolor and to put the markson the paper strips.

Use your set of pens tomake many different colormarks on paper strips. See

what happens when they getabsorbed up the paper.

Use larger pieces of paper,and draw little pictures anddesigns on them. Hang themin the basin and watch themodern art unfold.

Dip an M&M candy in water,and transfer the color to astrip of paper. Discover therainbows in the treats yousometimes eat.

Test the movement of natu-ral colors, called pigments. Trybeets, cherries, blueberries,

spinach, and other heavilypigmented plants. You cantransfer the pigment by put-ting a little sample of thematerial on the paper, andsmashing the juice onto thepaper.

Some pigments will notmove in water, but mightwhen other solvents are used.Try vinegar (an acid), rubbingalcohol, ammonia or paintthinner. Remember, thesesolvents should be used withadult supervision, and theyare best used outdoors.

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AFTERWORDS

While you were having fundiscovering hidden rainbows,you were actually dealing witha branch of science called

chromatography. In Greek,chroma meant "color" andgraph meant "to write." Scien-tists use this "color writing" toidentify different substances.

In your chromatography,you used filter paper, whichoperates on the principle ofcapillarity. You probablyalready know that your bloodflows through some verysmall veins called capillaries.

(Capillary means "tiny tube:')But where are the tubes

in paper? Any paper is madeup of tiny fibers that arepressed close torther. Thereare spaces between thesefibers that can act like tiny

tubes. Suppose you had twowalls of fibers and you putthem very close together(closer than you can see with-out a microscope). A waterdroplet sitting between thesetwo walls would look like this:

You can see that the sidesof the droplet are pulled upagainst the walls and the topof the droplet is curved down.Two sets of forces are at workhere. Cohesive forces withinthe droplet are workingbetween the water moleculesto keep the droplet together.At the same time, adhesiveforces in the paper fibers tryto pull, or absorb, the watermolecules up into the walls.It's like a tug-of-war!

As long as the adhesiveforces are stronger, the waterwill wet the walls. This meansthat water will be pulled upthe fiber tubes by a processcalled capillagy action. Whenthe cohesive forces betweenthe water molecules becomesequal to the adhesive forcesbetween the water and thefiber walls, the water stopsrising up the paper.

Next, think of the last timeyou saw a rain spout on theside of a building. If waterwas pouring out onto gravelunderneath, you'd find thelargest pebbles directly underthe spout. The lighter pebbleswere picked up by the watercurrent and carried away.As the current grows weaker,the larger rocks drop out of

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the stream. The lightest parti-cles get carried the farthestaway from the rain spout.

So, if you find that a greenpen mark leaves a blue bandof color with a yellow bandabove it, you now know atleast two things: (1) the greenpigment in the pen is actuallymade up of two colors, blueand yellow; and (2) the yellowcolor particles weigh less thanthe blue. Just like sand peb-bles in a stream, the yellowwas carried farther away,outside the blue.

Colors occur naturally inour most important organicsources (like the chemicalsproduced by plants and ani-mals especially plants).Scientists then use chroma-tography to separate andidentify these substances bytheir color. From there, theycan figure out how to maketheir own organic chemicalsin the laboratory. Their chro-matography is very sophisti-cated, but the results are nomore colorfui than your ownHidden Rainbows.

30

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3- !EWERTake a look into the thirddimensionwith this fan-tastic 3-D Viewer! You canuse your awn camera to takethe pictures. After the pic-tures are developed, you'llneed about 20 minutes tomake the viewer

YOU WILL NEED

A cameraPrint film for your cameraTape measure or yardstick

Cardboard tube at least 2" indiameter and 24" long(or you can use twotubes, each 12" long)

Scissors

Felt-tip marker or penPencil

Transparent tape

Years ago, 3-D Viewers werecalled stereoscopes. Eachstereoscope held two pic-tures of the same scene. Buteach plctJre was taken froma slightly different point ofview Normally when yculook at a photograph, yousee only ',wo dimensions:

height aria widtha flat im-age. But if you looked at one

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picture with one eye and theother picture with the othereye through a stereoscope,you would see an eye-pop-ping 3-D sceneone withheight, width, and depth.You can easily make a 3-Dviewer that will transformyour own photographs intoamazingly lifelike scenes. Butdon't forget to buy extra filmbecause there's a trick to it:You've got to photographeverything twice!

EXPERIMENT WITHYOUR EYES

Before you make your 3-DViewer, you should find outa little bi4. about how yousee. First, measure the dis-tance between your eyes. Ifyou are a grown-up (but nota giant!) your eyes are prob-ably about 21/2" apart, maybea little less. Do you thinkeach eye sees the samething? Find out by holdingup one finger in front of yourface, about 6" away Close

your right eye and observewhere your finger seems tobe. Line your finger up withsomething vertical, like adoorway. Then open yourright eye and close the left.Your finger will seem to"jump" back and forth, fromone side of the doorway tothe other. That's because youare seeing your finger dif-ferently, depending on whicheye you use. Your right eyeand your left eye see twodifferent "pictures," from twodifferent angles. When yourbrain puts the two picturestogether, you see thingsthree-dimensionally.

TAKING 3-D PICTURES

Please read all of the instruc-tions below, before you be-gin photographing. That wayyou will be sure to get goodresults.

You can use any ordinarycamera to take 3-D pictures.Simply load your camera andgo jutside on a fairly brightday. The idea is to take twopictures of the same scene,separated by about 21/2 ",

4 :3

since that's the way youreyes see

There are two goodways to take 3-D pictures.Method No. 1 is very easy.You simply hold the cameraup to your right eye and takethe picture. Thcn, for thesecond picture in the set,you hold the camera up toyour left eye. This will auto-matically move the cameraabout 21/2" to the left. if youuse this method, you musthold your head very stillbetween the two pictures,so that your angle of viewdoesn't change.

For Method No. 2, youput the camera on a table oranother solid surface. Put atape measure or yardstickbehind the camera, parallelto it. Take your first picture,then move the camera ex-actly 21/2" to the left. Nowtake the second picture.Again, you must be sure thatthe camera isn't twisted orturned between pictures

2

HINTS FOR SUCCESS

Be sure to photographevery scene twice!

3-D pictures work best ifthe different objects in thepicture are at different dis-tances from the camera. Forinstance, you might have abicycle in the foreground.There could be some ireesabout 4' behind the bicycle.The sky would be your dis-tant background.

Don't put the main subjecttoo close to the camera lens.The main subject should beat least 5' away from thecamera.

Remember that the subjectand the background mustremain exactly the same forboth pictures. If you arephotographing a streetscene, be sure to take thesecond picture quicklybefore a car moves, for

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instanceso that the streetscene will be unchanged. Ifyou are photographing aperson, he or she must re-main perfectly still for bothpictures. Don't let your sub-ject smile in Picture 1 andthen frown in Picture 2!

The pictures you take willneed to be cut so that theyfit in the 3-D Viewer. Onlypart of each picture will beused. Remember this whenyou are composing yourscene. Try to keep all of theimportant elements in thecenter of the "frame," orcamera viewfinder.

MAKING THE 3-D VIEWER

You will need to start witha long cardboard tube, likethe ones used to hold gift-wrappog paper. It should beat least 2" in diameter and atleast 24" long. Cut the tubeinto two pieces, each 12"long. (If the tube is longer,cut off the extra length anddiscard it ) With a marker orpen, label one ube LEFT andthe other one RIGHT.

If you don't have a card-board tube, you can use stiffwhite paper. Use two sheetsof paper, 81/2" x 11". Rolleach one into an 11" tubethat is 2" in diameter.

Now hold the tubes upto your eyes and look to-ward a light. If the tubes arenot held closely together,you will see two circles oflight at the ends. But if thetubes are held tightly to-gether at the far end, and justslightly separated at youreyes, the two circles of lightwill come together. You willbe looking through twotubes, but seeing only onecircle. Good! Now you knowhow to hold the tubes whenyou are viewing in 3-D.

VIEWING THE 3-DPICTURES

Remember that you pho-tographed each scene orsubject twice.

Find a set of two de-veloped prints and look tomake sure they are slightlydiffe,ent. You will notice thatin one picture you can see alittle more of the right side ofthe sceneor more of theright side of the background.That picture goes on theRIGHT tube. The other pic-ture, showing more of theleft, goes on the LEFT tube.Put both pictures, face up,together like a sandwich, andset them down on a flatsurface. Stand one of the

33

tubes up on the main part ofthe picture and, using a pen-cil, trace around the outsideof the tube.

Now cut out the circlefrom the pictures, cuttingright through both prints atonce. You will then have twocircular photographs, each alittle bit larger than the diam-eter of the tubes. Tape theright picture to the RIGHTtube and the left picture tothe LEFT tube, with the pic-tures facing in.

Hold the tubes togetherand face a light source. Atfirst, you might see two im-ages or pictures. But slowly,the two pictures will con-verge in your mind, and youwill see only onejust asyou saw only one circle oflight. Be patient. Sometimesit takes a minute or so foryour mind to bring the twopictures together. When theydo come together, you willsee that your main subjectstands out from the back-ground in a very three-di-mensional way!

AFTERWORDS

Hold on to your seats, horrorfans. Here comes a hideouslydisfigured man in a blackcape, with a face that looks

5.:

like it's been through a three-alarm fire. (it has!) He's aboutto thrust his gnarled hand outat you, but you're not fright-ened, are you After allit'sonly a movie, isn't it But

wait! This movie is calledHouse of Wax, and it's themost famous 3-D movie ever.When the hideous hand firstcame out of the moviescreen in 1953, it looked soreal that audiences all overAmerica screamed.

To understand 3-D, youhave to understand first thatyour eyes see separately andthat your brain fuses the twoimages together. You canprove that with your card-board tubes. Hold just aletube up to your right eye.Hold your left hand, palmopen and facing you, next tothe far end of the tube.Perhaps for a second, youwill see two separate im-ages. the hole in the end ofthe tube, and your handbeside it. But quickly yourmind will force the two pic-tures to merge. Then, bingo!You'll be looking at a hole inthe middle of your hand!

When you look aroundthe room, your eyes see twoslightly different pictures andyour brain fuses them to-

gether The two pictures yousee are flat, not three-dimen-sional It's only when thosetwo flat views become onethat you can actually see inthree dimensions. Now youmight cover one eye, lookaround, and say, "Everythinglooks three-dimensional tome." But in fact, you arebeing guided by other visualcues: the relative size of ob-jects, shadows, and yourpast experience

In tn. th, the world looksflat when viewed throughonly one eyeor throughonly one camera lens. Butwith two lenses, mountedside by side and about 21/2"apart, two pictures can betaken at oncein just theway your eyes take two"pictures" at once That'show stereo photographywas born In the 1800s, spe-cial cameras were designedwith two lenses, and specialviewing devices, stereo-scopes, were invented.

Then for many years 3-Dviewing went out of fashion.And it didn't come backuntil the 1950swhen televi-sion was invented. You see,people stopped going tothe movies because theywere too busy watching thetube. So Hollywood came

up with 3-D films to drawaudiences out to the theateragain. As with stereo pho-tography, 3-D movies weremade by shooting two ver-sions of the same sceneby strapping two huge moviecameras together. On onecamera, a filter "polarized"the light horizontally. Theother camera had a verticalpolarizing filter. The twoversions of the film werepiojected simultaneouslyand people in the audienceviewed the movie through3-D glasses with corre-sponding polarizing filters.That way, the left eye wasallowed to see only one ver-sion of the film, and the righteye was allowed to see theother version. Again, thebrain would fuse the twopictures

So why aren't 3-Dmovies all the rage today?Eye strain. Although 3-Dviewing is exciting, it canproduce headaches after awhile For that reason, you'llwant to go easy on the 3-DViews you made.

34

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INT BE".11/10How would you like to havean animal laboratory full of seamonkeys? That's what brineshrimp are sometimes called.You can raise dozens of brineshrimp in a small jar or bowland then experiment withthem to find out what theylike, and don't like! The raisingwill take a fc'.-i days, and thetesting, a tew minutes.

Shrimp Fe Ihing

YOU WILT. NEED

2 Clean wide-moutl, jars orlarge drinking glasses

Vial of brine-shrimp eggs(you can find these ata pet shop)

Magnifying glassRuler and pencil

Few tabu spoons of coarsesea salt (found in groceryor health-food stores)

Measuring spoon and cupMasking tape1 Package dry yeast

Note; You will also needall of the things listed under"Shrimp Testing!"

55

1Fill 2 clean jars or large

drinking glasses with

tap water and let themstand, unco.ered, for at least24 hours to rid the water ofany chlorine. Use this waterin all of your experiments.

Do not use metal containers!

2Take a close look At yourbrine-shrimr eggs un-der a magnifying glass.

What shape are they? Howmany of them could sit side byside on a line 1" long? Addabout one level tablespoon of

sea salt to a cup of your stand-ing water and stir until dis-

solved. This will make the saltywates called brine. Pour thebrine into a clean glass jar

and mark the level of the liquidwith masking tape. Bigger jars

may need more cups of brine.Sprinkle a pinch of brine-shrimp eggs on the surface dthe brine. Set the jar in a warmplace such as a sunny spoton the kitchen counter. Youwill have to check your jarsevery day and add more brineup to the tape mark, as needed.

tit 4,19.0 Se HOW MANY SHRIMP COULD you FIT SIDE By SIDE?

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3Watch your containercarefully and oftenduring the next two

days. Hold your container upto the light and use a magnify-ing glass to see what's hap-pening. The new shrimp willbe very tiny almost invisible!Look for tiny white dotsswimming wildly in the water.

If you don't see anynew shrimp within 3 days,something has gone wrong.Start again, this time using dif-ferent amounts of salt in yourbrine. Or try different wattr,such as distilled water. Or usepond water filtered through apace- towel. If you still don'thatch any shrimp, you mightneed a new batch of eggsa new brand, if possible.

4Once you see shrimp,sprinkle a few (veryfew!) grains of pow-

dered dry yeast on the surfaceof the water every couple ofdays. If the water stays milkyafter a while, you are givingthem too much food.

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5Each day, spendsome time studyingyour brine shrimp.

How do they change as theygrow? Females are usuallylarger than males. How elsecan you tell them apart?Watch for eggs and "babies:'But don't expect your shrimpto get too big. Even the big-gest "adult" shrimp are onlyabout 1/2" long. In your labora-tory, they may not even growip to be that big.

Now that your shrimp aregrowing well, you can eitherkeep them as pets (in whichcase you have to name all ofthem!) or you can turn yourcollection of brine shrimp intoan animal laboratory, and putyour shrimp to the test!

FOODICER

Shrimp 'resting

YOU WILL NEED

Plastic spoonTall, narrow jar or glass

Construction paper or brownpaper bag

Rubber bandFlashlight

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1Test to see how yourshrimp react to light.If the brine shrimp are

already in a tall glass, great!If not, use a plastic spoon tomove some of them to a clean,tall glass or bottle filled withbrine. Wrap constructionpaper or seve at layers ofbrown paper around theoutside of the glass. Hold thepaper in place with a rubberband. Shine a flashlight directlydown onto the surface of the

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brine for 3 minutes. Whileholding the light in place,

quickly remove the paper.Where are most of the shrimp?Can you tell what directionthey are swimming in?

2Pour a jar of yourshrimp-and-brinemixture into a flat glass

baking dish. Stretch red cello-phane over one half of thedish and blue over the otherhalf. Watch for a while. Do theshrimp seem to prefer oneend of the dish? Can youguess why?

See how well yourbrine shrimp can takethe cold. Seal an ice

cube inside a plastic sandwichbag and put it in the brine, atone end of the baking dish.Watch for a few minutes.How do your shrimp react?Remove the ice cube. Thenrepeat the experiment butput hot water in the plasticbag instead of ice.

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37

4Put some shrimp eggsin the freezer for aday or so. Will they still

hatch, after they've been fro-zen? Put a different batchof eggs in an oven fora fewhours at 150 degrees. Can youstill get these to hatch whenyou take them out of the oven?

5With a plastic spoon,put a few shrimp into aseparate cup half full of

brine. Mix a drop of red foodcoloring 1.11 a small pinch of

yeast, and ',ntly add the redyeast to the cup. After 5 to10minutes, spoon out some ofthe shrimp. What do you see?If the shrimp have eaten thered yeast, you should be ableto see their digestive systems.

AFTERWORDS

Now that you've done somany different experimentson the brine shrimp in youranimal laboratory, it's time toplay that great game showThe $15,000 Brine ShrimpFortune Quiz! For I themoney an a trip to Salt LakeCity, Utah, answer this ques-tion: Where do brine shrimpcome from the ocean, theforest, or the desert?

5 n

Believe it or not, theanswer is the desert. Brineshrimp are found in Americain the dry areas of the South-west, where there is little rain-fall and many lakes dry up formuch of the year. When raindoes fall, it fills the lakes againand also forms puddles Brine-shrimp eggs hatch in thesesalty lakes and puddles, andlive until the hot sun evapo-rates the water completely.Then the next batch of brineshrimp eggs, which were laidwhile the shrimp were alive,pile up on the desert and waitfor the rains to come again.

Brine shrimp are crusta-ceans like lobsters, crayfish,and crabs. So naturally you'rewondering: How did brineshrimp get out of the oceanand find their way to Utah?Actually, although brine shrimpare in the same class withlobsters, they are not reallydescended from shellfish andthey never did live in theocean. Instead, brine shrimpevolved from other freshwatercrustaceans. They've beeninland for thousands andthousands of years.

In your briny behaviorexperiments, you tricked yourbrine shrimp into thinking therewas a lot of food around

when there wasn't! Brineshrimp are attracted to areaswith lots of green algae, be-cause that's what shrimp eat.Green algae absorb most ofthe blue light in the sun's spec-trum, and that leaves mainlyred light shining on the shrimp.By putting red-colored cello-phane over the brine shrimp,you were able to trick theminto thinking that the waterwas full of algae. That's a prettygood trick much easier thanhaving to come up with a panfull of algae!

But what happens to theeggs if the weather is very dryand hot for a very long time?When you checked out thebriny behavior of your tinyshrimp, you probably foundout that the eggs will hatch,even if they've been baked inthe oven fora few hours. Andthey will hatch even if they'vebeen frozen. Brine-shrimpeggs are amazingly resistantto the destructive forces innature, because desert tem-peratures are often blisteringat noon in summer and freez-ing at night in winter. Some-times brine-shrimp eggs \Allsit around on the desert for

2 or 3 years before the con-ditions are right for themto hatch.

The Great Salt Lake in

Utah is another main residencefor brine shrimp, but there thelife cycle is not interrupted bythese long drying-out spells.Many of the brine-shrimp eggsyou find in pet stores comefrom the Great Salt Lake. Peo-r.. ;uy these brine-shrimpeggs to raise them for foodfor their tropical fish, becausetropical fish grow more quicklywhen they're fed live food.

But who eats brine shrimpin nature? Ncbody. Not manyother creatures "e in the saltypuddles and lakes. In the GreatSalt Lake, there are only twokinds of flies, one species ofinsect, and some algae floatingaround so the brine shrimppretty much have the run ofthe place.

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C II ENINACI, SSIf you like plants and gardens,

this project is for you! It is alsoa quick way to have a gardenof your own, especially ifyou don't have room forone outdoors.

YOU WILL NEED

Some empty, wide-mouthglass jars with lidsthe bigger the better(A pickle jir from arestaurant is great!Ask around.)

Baking soda

Some pebblesFrom a gardener's shop: small

quantities of horticulturalcharcoal, standard pottingsoil, vermiculite or perlite,peat moss, sharp sand(or aquarium sand), bonemeal (if available), and

some small plants (or findthem in a vacant lot)

Pan or basin or pail formixing soil

Old nylon stockingsScraps of jagged rocks or

pretty stones

Pieces of wood that are wornfrom being outdoors

Scissors, spoonSome Plasticine or

modeling clay

IWash and rinse yourpickle jar. Sprinkle 2 or3 tablespoons of baking

soda on the inside of the lidand add some water; thishelps get rid of the vinegarsmell. Lay your pickle jar on itsside between two magazinesor b.:01<s so it can't roll.

2Wash and rinse enoughpebbles to make a 1/2"to 1" layer on the bot-

tom of your jar. Take V3 as

much charcoal and wash it:Put it in a pan or basin, add

water, stir, and carefully pouroff the dirty water. (You mightwant to use a strainer.) Sprinkle

charcoal evenly over the rocks.These rocks and charcoal are

your garden's "drainage bed!'

The charcoal acts as a filterand lets clean water rundown onto the rocks.

3Cut up some old ny-lons; overlap the piecesto make a thin layer to

cover your drainage bed. Thisseparator will keep soil fromgetting into the bed.

4 Mix up your soil, follow-ing this recipe: 6 cupsstar _lard potting soil,

2 cups vermiculite or perlite,2 cups peat moss, 1 cup sharpsand or aquarium sand (if youuse beach sand, be sure towash it well just like thecharcoal), and 1 cup horticul-tural charcoal. If you can findbone meal, mix in 1/3 cup. Ifyou can't get these things, tryordinary soil from your yard.

5Now, let your imagina-tion run wild and designyour garden! You may

want to make it look like a littlepiece of the real world withhills and pathways. Look forpretty stones or rocks andtwigs. Think of a tiny plantas a tree; create a forest!

6.,

Use d spoon to land-scape your garden.Sprinkle some of your

soil over the separator. Youwill need enough soil to coverthe roots of your tiny plants.Dig holes in the soil whereyou want your plants to go.

IIf your plant is potted,hold it upside down inone hand. Gently tap

the rim of the pot on the edgeof a table or sink. (Cover thefloor underneath with news-paper, to catch any loose soil.)Slip the pot off the plant.Knock much of the dirt offthe roots. Pop your plantsinto their holes. Switch themaround until you like the waythings look. Then, gently patthe soil around each plant.Take out any extra soil. Spoona bit of water around eachplant, a spoonful at a time.Don't soak the soil!

40

8Screw the lid on tightand put your new ter-rarium near a bright

window but not in directsunlight! (You can use plugsof Plasticine or modeling clayas wedges to keep it fromrolling.) If a place is comfort-able for you (not too hot, nottoo cold), it will likely be com-fortable for your plants. Yourplants will grow and leantoward the light, so turn yourterrarium around once ina while.

Now, check your"sprinkler system:' Youshould always be able

to see some water droplets onthe inside of the glass. If thereare so many that you can'tsee inside the jar at all, theremay b: too much water inyour terrarium's "atmosphere:'In that case, take the lid off fora few hours. Or it may be thatthe sunlight is too strong; try ashadier place. If there are nowater droplets, add somewater to the soil.

Once you get a nice bit ofmoisture on the glass you cantighten the lid, leave it tightand that's it! So just sit back

LARGE P 1 cKLE JAR FROM RESTAURANT

and watch your garden grow!You'll probably nr..ver have toworry about watering yourplants ever again.

VARIATIONS

You may want to try a ter-rarium with cactus plants. Youwill need sandy soil. Here'sthe formula: Mix together1 cup potting soil, 3 cups sand,1 cup perlite, 1 cup charcoal,and 1 cup peat moss. Thisgarden will need very littlewater and very little drainage.(Cover the surface with sandto make it look like a desert.)

You can leave the lid off.If you have mosses and

ferns growing in your yard,you can make a sealed terrar-ium for these. Use the stan-dard mix recipe but add extrapeat moss. Or try planting aterrarium with whatever smallplants you can find :n a lawnor vacant lot.

Sometimes a pickle jar sit-ting upright with just one ortwo plants makes a neat te.Trar-

ium. How can you decoratethe lid? Make a cradle out ofsoft rope or cord (macrame)and hang up your garden.

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What other containers canyou use for terrariums? Glasses,bowls, jars, an old aquariumare possibilities; use plasticwrap to cover them.mne bot-toms from the biggest plasticpop bottles are great! Just cutthe bottle's top off; removethe green or black plastic bot-tom and plant your garden init. Then turn the bottle bottomupside down and use it as theterrarium cover. You couldmake these for gifts!

AFTERWORDS

Dr. Nathaniel Ward, an Englishsurgeon, living in the 1820s,was interested in moths. Heput the cocoon of a sphinxmoth in some damp soil ina glass jar and put the lid on.He looked at it often, hopingto see the adult moth gettingout of its cocoon. But he alsonoticed that some grass and a

small fern had sprouted fromthe soil. Being a scientist, hewas of course interested inthe unexpected and decidedto see how long the greenplants would live in the sealedjar. They were still doing finefour years later, but then the jarwas damaged while he wasaway. (No one rememberswhat happened to the moth!)

How do the water drop-

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lets get up on the inside of thejar? You put the water into thesoil. When plants are growing,their roots absorb water fromthe soil. This water goes upthrough the stem to the leaves.Inside the leaves, the plantuses some of the water tomake food for itself, to grow.But there is more water in theleaves than the plant needsand this extra water is givenoff by the leaves. This processis called transpiration.

Water that has been trans-pired goes into the air in thejar in the form of a gas, orvapor. When this water vaporreaches the cool, inner surfaceof the jar, it condenses to formtiny drops of liquid water.These tiny drops run togetherto form the tiny droplets youcan see. Gradually, these drop-lets will run down the walland into the drainage area.From here the roots pick upthe water again and the wholebusiness repeats itself. The tripthat the ,water takes from thesoil, through the plant and theleaves, into the air, onto the

wall and back into the soil iscalled a water cycle.

How can your plantbreathe if the jar is sealed?

Plants takc, in oxygen and give

out carbon dioxide just likeyou do! Green plants alsophotosynthesize in sunlight.In photosynthesis, plants takein carbon dioxide and give offoxygen (and some water).So the plant recycles its owncarbon dioxide and oxygen.Tiny organisms in the soil causedead organic (once alive)particles also in the soil todecompose, ct decay, gradu-ally. As they decompose, theparticles release carbon diox-ide into the air in the jar.

Plants also need theelement nitrogen to makeproteins. But these proteinmolecules lock up nitrogeninside the growing plant. Youmay see your plants grow fora while and then stop. Someof the leaves may wilt, dry up,and fall off into the soil. Don'tworry! Soil organisms willdecay the dead leaves andrelease their nitrogen. Thisnitrogen goes back into yourplants and they will perk upagain. This completes thenitrogen cycle.

These cycles will repeatover and over again, re-creat-

ing an "atmosphere" just likethe Earth's. Your terrariumreally is a miniature world!

42

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Ir.ese science toys are somuch fun you'll want to makethem as gifts to give to yourfriends and family... afteryou've made your ow, foplay with,-of course! Eachshould take no more than30 minutes to put together.

SKYHOOK

Can you balance your belt onyour nose? Make cereal dancearound? Create a tiny ocean,complete with waves, irr:dea bottle? Do these sound likesome great feats of magic?Guess wt wt? They're betterthan magic: They're scientific!

YOU WILL NEED

1 Wooden 12" ruler1 Uncooked egg in its shell

Some marling clay or doughFelt-tip markersYam scraps

1 Jackknife with a heavy

handle (optional; to beused by adult)

Paper, pencil, scissors

2" by 4" Piece of wood,Ks" to 1/4" wide

(basswood or plywood)Coping saw or scroll saw

1-1 ,r) ,.)

W WI n SCIENCE1

Try to balance a ruleracross the tip of onefinger. You will probably

find you can only do it if yourfinger is at the 6" mark or rightin the middle of the ruler. Themidpoint of that ruler is thecenter of gravity where allthe weight of an object isconcentrated.

2Now try balancing araw egg on either end,in your hand. You will

find that it's too hard to dn:The base of the egg is tuusmall and the center of gravitytoo high. But then tap thesmall end, making & hole about3/4" wide across the top.Empty the eggshell and washit out well. Place a marble-sized piece of clay or doughinto the eggshell so it stickson the center of the bottomof the shell. Now balance theegg on its larger end. In fact,you probably can't even tip itover! You've lowered thecenter of gravity so far downthat it is impossible to topplethat egg.

3Let's get back to ther ter for a few minutes.lry balancing that same

ruler upright on one fingertip.Almost impossible, isn't it?That's because the centerof gravity is so high, the rulerbecomes very unstable. Nowask an adult to open a jack-knife so the blade is at a rightangle to its handle and stickthe knife into the edge of theruler at about 11/2" from thebottom. That ruler will balance

on your fingertip! You havelowered the center of gravityso that it is below the rulerand in the knife and is now' ectly under your finger!

4Now you're readyto make the skyhook:Trace the skyhook pat-

tern onto gib . paper and cut itout. Place the paper patternon the wood and trace aroundpattern. With a coping orscroll saw, cut the wood alongthe line of the pattern. To usethe skyhook, place a leatherbelt, at about the middle, intothe skyhook's groove soboth ends of the belt hangtoward the longer partof the siryhook. Nowhold the long endof the

6.:

slryhook on the tip of yourfinger. It is amazingly stable!Place the long end of theskyhook on your nose. This"magical" toy makes agreat gilt!

STATIC CEREAL BOX

Have you ever walked acrossa carpeted room, reached forthe metal door handle, andbeen zapped by an electricalshock thLt really tingled?Or have you ever rubbed aballoon on your sleeve andtried to stick it on a wall?You've been playing withelectricity! This toy makes useof positive and negative elec-trical charges to amuse andamaze everyone.

YOU WILL NEED

Balloon

Salt, pepperPlastic combPiece of nylon, fur, polyester,

or wool (or wear clothesmade of any of thesematerials)

Handful of puffed-rice orwheat cereal

1 Box with a clear plasticcover (the type that cardsor stationery comes inworks well)

Tape

IIf you haven't rubbed aballoon cn your sleeveand stuck it to the wall,

give it a try. Don't just watchwhat happens: Listen for thecrackling sound made by themoving electric charges. If theroom is dark enough, youmight even see sparks.

2Pour a little salt andpepper on a flat sur-face. Mix it up well.

You will now be able to sepa-rate the pepper from the salt.Here's how: Rub the combwith nylon, wool, or fur (poly-

ester works well also). Holdthe comb about 3/4" to 1"above the mixture and watchthe pepper jump up to thecomb. The salt will jump too,but not as high You can easilyremove the flakes of pepperfrom the salt mixture!

71)

3Now make the StaticCereal Boxa morepermanent toy for play-

ing with electrical charges. Putabout /3 to 1/2 cup of cerealinto the box. Place the clearpla iic cover over it, and tapeit down. Rub the box coveragainst you, if you are wearingsomething made of nylon,wool, fur, or polyester; or justrub the cover with a piece ofone of these fabrics. Turn boxso cover is up and watch thecereal cling to the top! If youplace your finger on the cover,the cereal will dance aroundand shoot off the top. Have arace with wmeone else andsee why can get one piece ofcereal from c,ne side of thecover to the other. Mark racingfines on the cover and givethis toy as a present.

STORMY SEASSODA BOTTLE

Did you ever shake up a bottleof oil-and vinegar salad dress-ing and pour it over your saladonly to wind up with toomuch vinegar? Then you knowthat oil and water (or water-based vinegar) don't mix. Youcan pour them together, shakethem vigorously, but eventu-ally, they will go their separateways.

YOU WILL NEED

Empty 1- or 2-liter colorless,plastic soda bottlewith cap

Blue food coloringMineral oil (available in

drugstores) or clear saladoil (you % ,ill probablyneed 1 pint of oil for the1- liter bottle and 2 or 3pints for the 2-liter bottle)

Scissors

Small scrap piece of white,bleach-bottle plastic

1Pull off the plastic cupat the bottom of thesoda bottle, if there is

one, and save. Fill the bottleapproximately half full of coolwater. Add as many drops offood coloring as you desire tomake the water a nice bluecolor. Mix well. Pour in the oil.If there is still space left in theboti.le, add more oil or wateruntil the bottle is filled rightup to the neck.

7

45

2With the scissors,cut out a tiny sailboat(or make several) from

the scrap of bleach-bottleplastic. Insert the boat throughthe neck of the bottle. Watchwhat happens. It floats throughthe oil but stops before it getsto the blue water!

3Close the cap verytightly. (You might wantto place a small square

of plastic wrap on top beforereplacing the cap.) Rock thebottle back and forth on itside. Watch the waves andbubbles form. To calm yourseas, place the bottle backinto its plastic bottom and letit set for a while. The oil andwater will separate againuntil your next storm at sea!

AFTERWORDS

These science toys do indeedseem like magic tricks to any-one who doesn't understandthe scientific principlesbehind t

SKYHOOK

When you balance a ruleracross one finger; you are dem-onstrating the center of gravity.In a regularly shaped object,

the center of gravity is at thecenter of the object. An egg'scenter of gravity is near thecenter of the egg (on the inside)yet because its base is toosmall, it is unable to balanceitself. To balance an object, wecan lower its center of gravityor widen its base.

In an irregularly shapedobject, like your body, thecenter of gravty is any pointwhere all of the weight of thatbody is concentrated at anyparticular time. The center ofgravity is different when westand, sit, or bend. Anyonewho skis or skates or dancesknows how you must continu-ally change your position tomaintain balance: With move-ment, your center of gravityis constantly varying. The sky-hook balances on your finger-tip because the belt has pulledthe concentrated weight, orcenter of gravity, to a pointbelow your finger. As 'ongas that point stays be!, w yourfinger, you can balancethe skyhook.

STATIC CEREAL BOX

All material things are madeup of tiny particles calledatoms. Every atom containsthree types of particles: elec-trons, which are negative par-ticles of electricity; protons,which are positive particles;and neutrons, which have noelectrical charge. Electronsmove about in many atoms;protons and neutrons are sta-tionary. Generally, an objector matter has an equal numberof electrons and protons, sothe positive and negativecharges cancel out each other.But when an object is rubbed,the electrons begin to moveabout and the friction createdwill rub electrons off oneobject and onto another. Oneobject then gains more elec-trons, making it negativelycharged.

The balloon you rubbeaon your sleeve gained elec-trons from your sleeve's fab-ric and became negativelycharged. As the ballooncomes in contact with theneutral wall, it pushes thatsection of the wall's electronsaway (like magnets, negativecharges repel regativecharges) and leaves moreprotons on that part of the

77;

wall, which becomes posi-tively charged. Since oppo-sites attract, the balloon sticksto the wall for a while. Aftera bit, the negative electronspass onto the wall from theballoon, and it falls.

Though the cereal inthe box was neutral, rubbingcaused the box top to be-come charged. That createdan attraction (like the balloonand the wall) and made thecereal jump up to the cover.Touching the box top ground-ed the pieces of cereal andcaused ..hem to jump away,or be repelled.

STORMY SEASSODA BOTTLE

Water has been called theuniversal solvent because somany other liquids and solidscan be dissolved in it. Oil,however, cannot mix withwater. When we shake theStormy Seas Soda Bottle, littledroplets of oil are suspendedand spread through the bluewater. More shaking will pro-duce smaller droplets of oil.However; if left to sit for awhile, the oil droplets clingtogether to re-form intoone solid layer.

Tie -bleadto give arlook anyfun! Do itwill take atie-bleach

YOU MUGlass mez

Liquid chlNewspapCotton svr

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colorsLemon pisOld or ne)

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by using tiE

Tie-bleaching is a great wayto give an old shirt a newlookand it's good cleanfun! Do it on laundry day. Itwill take about an hour totie-bleach cne T-shirt.

YOU WILL NEED

Glass measuring cupLiquid chlorine bleachNewspapersCotton swabs, such as

Q-TipsConstruction paper in various

colorsLemon juiceOld or new 100% cotton

T-shirt in a color otherthan white

15 or 20 Rubber bandsWashing machineLaundry detergentA stick for stirring

Optional:Blue jeansWhite T-s and a box

of dye

Heewe vou ever seen tie-dyed

f-shirts? ihis month, you canmake some fabulous patternsby using tie-dye techniques

" BLUESin reverse! Just wrap somerubber bands around an oldT-shirt, throw it in the wash-ing machine, and let thechlorine bleach do the restof the work. While you're atit, you may want to makeyourself a pair of BleachBlues. That's what we callblue jeans that have beenbleached to show all theirfaded glory. Find out whatelse you can do withbleachand get the laundrydone at the same timewith this super-cool scienceactivity!

11,

Before you beginworking withbleach: It's a good

idea to change into oldclothes, just in case you acci-dentally splash some bleachon yourself. Bleach shouldbe handled very carefully.Avoid contact with your skinDon't put Jur hands in thebleach and don't breathe thefumes.

Hold a glass measuringcup over a sink and care-fully pour in a very smallamounta few table-spoonsof liquid chlorinebleach into the cup. Then goto a well-ventilated area ordo this part of the activityoutside. Spread out someold newspapers to work on.Dip the end of a cottonswab or Q-Tip into thebleach and use it to draw ona piece of colored construc-tion paper. How quicklydoes the bleach work? Doesit work just as fast on eachcolor of paper?

Now try squirting a littlelemon juice onto a piece ofconstruction paper. Does itbleach the paper? (i.e pa-tient. It will take longer andthe results will be less dra-matic. But when the lemonjuice is dry, you should see alight spot.)

2To tie-bleach one ormore I-shirts, start bytying small sections of

a 100% cotton T-shirt with

7 C,

rubberbands. Wrap the rub-ber bands tightly aroundeach section of shirtthetighter the better. If you wanta large section to remainunbleached, then you willhay,' io use lots of rubberbands there. Hint: Most rub-ber-band tying will make acircular pattern on your shirt.But if you want stripes, rollthe shirt up like a jelly roll orsausage and then wrap therubber bands around thesausage.

3Fill your washing ma-chine one-fourth fullwith hot water (On

most washers, you can stopthe machine from filling allthe way by lifting the lid )Pour in 3 or 4 cups ofbleachabout 32 ounces.Add 1/4 cup of laundry de-tergent. Put your rubber-banded T-shirt into thewasher and let it sit (Don'tclose the lid because youdon't want the washer to fillup any further yet!'. Use a

stick to stir the shirt aroundin the bleach. After 5 or 10minutes, lift the shirt out withthe stick and look at it. Hasit faded some? If not, addmore bleach to the waterand let the shirt soak foranother 10 minutes. Stir withthe stick from time to time.

Note: When wet, your shirtwon't look as faded orbleached as it probably is.Don't expect it to turn a pale,pale color. It will get lighteras it dries.

Leave the shirt in thebleach -water until it is

noticeably lighter, then closethe washing-machine lid andlet it run through its cycle.That way the bleach will becompletely rinsed from theT-shirt. Leave the rubberbands on until the shirt iscompletely washed andrinsed Then take them offand either let the shirt dryon a hanger or throw it inthe dryer.

HINTS FOR SUCCESS

Don't try to tie-bleachmany different colored T-shirts together at the sametime.

Tie the rubber bands verytightly, so that the bleachcan't set to the tied parts ofthe shirt.

Use a lc", of bleach. Youmay need to use as muchbleach as water, so don't letthe washing machine fill toomuch.

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VARIATIONS

Try tie-bleaching a T-shirtusing lemon juiceand thesun! Wrap the shirt with rub-ber bands, soak it in a sinkpartially filled with bottledlemon juice, and then putthe shirt outside to dry in thesun for several hours. Don'tremove the rubber bandsuntil you think the sun hasdone its job.

If you want to make BleachBluessuper-faded bluejeans--follow the instruc-

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49

tions above bes:nning withStep 3. You can bleach bluejeans in the same washerload with your tie-bleach T-shirt if the T-shirt is also adark color, like the jeans.

You can also tie-bleachshirts that have been dyedor tie-dyed first. Use 100%white cotton T-shirts andpackaged dye. Follow theinstructions on the packageof dye. Make sure the dyedshirts are completely dry be-fore you start to tie-bleachthem. This is a good way tomake several tie-bleachedshirts to be given as gifts.

AFTERWORDS

Bleaching is a process that isperformed on many prod-ucts in this country, not justfabrics. Wheat, sugar, woodpulp and paper, furs, andhuman hair are all bleachedusing one of several differentchemical compourds.These compounds, calledoxidizing agents, includechlorine bleach, hydrogenperoxide, and sodium hy-pochlorite. All are acids, andbasically they all work thesame way: A chemical

7;

change takes place when thebleach reacts with oxygen.And any time a chemicalchange occurs in a sub-stance, the chances aregreatabout 20 to 1thatthe new substance will bewhite or colorless.

Can you see why lemonjuice, an acid, might be ableto bleach a cotton T-shirt ifit's left out in the sun (ex-posed to oxygen) longenough? Actually, the sundoes a very good job ofbleaching fabrics, even with-out the help of lemon juice.You might find some exam-ples of sun-bleaching in yourhouse. Look at your couch orchair covers, and then find aplace on the couch that isn'tusually exposed to the sun.Furniture, wallpaper, pho-tographs, books, papers, andeven the clothing you wearare all affected by the sun'sstrong rays It just takes thesun longer to bleach thesethings without the help of anoxdizing agent such as anacid.

Three hundred years ago,when linen and cotton fab-rics were first bleached, the"acid" used was sour milk.The cloth was soaked forseveral weeks in sour milk,then washed and spread out

on the grass for several moreweeks, to bleach in the sun.Then that whole process wasrepeated five or six times! Ittook months to make clothwhite.

Today, when fabric manu-facturers bleach cotton indus-trially, the process not onlywhitens but also removeswaxes, fats, and bits ofbrown husk that are presentin the cotton plant The cot-ton is bleached with hydro-gen peroxide and otherchemicals, and the cloth canbe made white la matter ofminutes! Most cotton, linen,and silk fabrics are bleachedbefore they are dyed.

The flour you eat inbreads and cakes was actuallybleached with some form ofchlorine. You know that liq-uid chlorine laundry bleachis very harmful if swallowed.The secret to bleaching flouris that chlorine dioxide gas isused. In fact, the elementchlorine itself is a gas Theslightly yellow or tan pig-ments in the flour are quicklybleached when they comeinto contact with the gas, but

the flour itself absorbs verylittle chlorine

What else gets bleachedon a regular basis? Your hairdoes, if you swim in a chlon-nated outdoor swimmingpool. People often say thattheir hair gets sun-bleachedin the summer sun, butthey're only half right. It'susually the combination ofchlorine from a pool and theexposure to the air that doesthe best "bleach job."

Wood pulp too is chem-ically bleached so that plainwhite paper can be madefrom trees that were ob-viously not white to startwith Even for wood pulpthat is only going to bemade into somethingbrawnlike a cardboardcartonsome bleaching 'srequired In that case, thebleach doesn't necessarilymake the pulp white, butit does remove the part ofthe pulp that isn't useful inpaper-making

50

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decorate one Good Looker.

YOU WILL NEED

Empty box from aluminumplastic wrap,

or waxed paperMasking tape

Utility knife or paring knife2 Small mirrors about 2" x 3"

(availaole at Woolworth'sand other variety stores)

White glue (Elmer's Glue-Allor similar brand)

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Everyone know .,..hat you seewhen you look .,to a mirror.You see yourself. But whathappens when you look intotwo mirrors? If they're set upright, you can see over andaround things that are blockirigyour view. That's how tanksand submarines get a good'ook at the world outside dabove them. They use mirrors,mounted inside a long tube.Whether you call that tube aperiscope or a Good Looker,it's a great toy and a lot of funto use!

1Cover the sharp, ser-rated edge of an emptyaluminum foil or plastic

wrap box with one or twolayers of masking tape. Thiswill keep you from cuttingyourself c n the edge whileyou work.

2Use a utility I:nife orsharp paring knife tocut a window in the

front side of the box it oneend of it. The window shouldbe about11/2" inches long,and almost as wide as the box.Be careful wit.; the knife. Thismight be a good time forparents to show childrenhow to use one. Cut anotherwindow of the same size inthe back side of the box, atthe opposite end.

3Put one of the mirrorson its edge in the box,so that it faces the first

window at about a 45-degreeangle. One end of the rr'rrorshould be wedged into thecorner nearest the windowThe other end of the mirrorshould be taped to the back

side of tl.e box. Don't worryif the angle isn't exactly 45

degrees, because the siz,the box will determine whatangle you use. Place the othermirror parallel to the firstone in a similar position atthe other end of the box.(See the diagram.)

4Tape the mirrorsplace and close the"nx. Look through one

wirdc,.. ) see if your peri-scope is working. If it is, openthe box and slue the mirrorspermanently in place byrunning a thin line of whiteglue along each edge of eachmirror. If the periscope isn'tworking, adjust the positionof the mirrors. Make sure the

mirrors are parallel and thatthey are facing into the middlenot the corners of the box.

5When the glue hasdried and you're surethe mirrors won't move,

close the lid of the box againand glue or tape it shut.

6Decorate the outsideof your Good Looker,using colored paper,

wrapping paper, stickers,markers, crayons, magazinecut outs, fabric scraps, or any-thing else you have on hand.If you're making this periscopeas a gift for someone youknow, why not put her nameon it as part of the decoration?

What can you see with yourGood Looker? Does it giveyou a good way to look atbirds? What happens whenyou try to walk toward some-thing you see in your peri-scope? What if you stick it outthe window and try to lookat the sky?

Perhaps an older personcould use your periscopeto see what's on top of therefrigerator...or on a shelfthat's too high to reach...or to find out what's underthe couch without bendingover. Think of as many waysto use your periscope asyou can!

VARIATIONS

Don't look now, but there aremore things you can do withmirrors:

Set a small mirror at anangle in a shallow pan ofwater. Place the pan near awindow so that a direct beamof sunlig' hits the mirror.It will make rainbows onthe wall.

To see yourself as otherssee you, hold two mirrc)rs atright angles so that they forma corner or ar L Tape the mir-rors together and set thema table. Look into the corner,

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where the two mirrors cometogether. Do you notice any-thing different about yourself?This is how you really look toother people. No matter howmany times you've looked ina mirror, you've never seenthe face tnat other people seebecause the mirror imageyou usually see is backward.

Scratch your right ear,while looking into the L-shapedmirrors. Did your right earseem to be on the wrong side?That's because you're actuallylocking at a mirror image of amirror image! Try to point toa particular tooth...or yourbiggest freckle...or try towipe a crumb from your race.It's not so easy! This doubleimage is just one of the manydeceptions of mirrors.

AFTERWORDS

Mirror, mirror on the walland in telescopes andcameras, in supermarketcheckouts, in photocopyingmachines. In fact, just abouteverywhere you look you'llfind mirrors being used incountless and surprising ways.

And which one is thefairest of them all? That's hardto say, but the biggest of themall is the mirror in the world'slargest telescope on Mount

8

Semirodriki in the U.S.S.R. It is236.2 inches across just 36.2inches bigger than the Haletelescope on Mount Palomarin California. With instrumentssuch as these, astronomerscan see farther into spacethan they ever could before.Imagine sitting in the observer'scage in the middle of a gigP. iticsteel tube, with your back toti te sky. You're facing an astro-

nomical mirror, as the lightfrom the stars travels past youdown the tube, and is reflectedback to a spot just in front ofyou called the prime focus.Many people think that thelenses are responsible for themagnification provided bythese enormous telescopes.But actually, except for lesmall eyepiece that pinpointsthe prime Locus, there are nolenses in these powerful re-

flecting telescopes. Instead, asingle concave mirror gatherslight from the stars and mag-nifies it thousands of times!

Unlike the concave mir-rors used in telescopes, whichare expensive and difficult tomake, flat mirrors are fairly in-expensive and they are being

used in industry in a v iety ofnew, problem-solving ways.Mirrors are at work in the new-est supermarkets and largedrugstores. For several yearsnow, laser-beam checkoutsystems have been used toread the Universal Pr. ductCode (UPC) prices thosevertical black lines you find onalmost everything you buy.The checkout clerk passes theUPC markings over a laserscanner, and the productname and price are automati-cally rung up on the cashregister.

But however mirrors areused, the principles of reflectedlight are all primarily t'.2 same.What l'iappens with a flat mir-ror is this: Rays of light coming

from an doject ;ri front of themirror strike the mirror andbounce off at an angle that isequal to the original angle oflight. For instance, let's saythat you are in front of a smallmirror at point A, and yourfriend is at point B. (See theillustration.) The light comingfrom you strikes the mirror atpoint C. If you drew an imagi-nary line perpendicular to themirror at point C, then youcould measure this angle,which is called the incidentangle. Your friend can see you,

because the light bounces offthe mirror from C to B at anangle that is equal to theincident angle.

The interesting thing aboutthese principles of reflectedlight is that when we look atreflections coming from a mir-ror, the light is actually comingfrom point C on the mirror.But the image appears tocome from a point behind themirror point Z in the diagram.You can prove this with a cam-era that adjusts for distances.

Stand 3 feet away from themirror and set the camerafocus for 3 feet. The pictureyou take will be blurry. Only ifyou focus the camera on theimage of yourself behind themirror, which is 6 feet awayfrom where you are standing,will the picture be clearand sharp.

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Sly" rAEJeepers creepersit's slimetime Time to get down inthe dirt and find out what it'slike to live in the.world ofearthworms. It will takeabout an hour to build ahorm for wormsand thenyou really ought to keep aneye on them all month.

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YOU WILL NEEDSmall, heavy cardboard

cartonUtility knife or scissorsAcrylic "box"-style picture

frame about 11" by 14",or sheet of acrylic 11"by 14"

Ruler

Pencil

Masking tape or staplerPlastic garbage bagDuct tapeTrowel or small shovelPotting soilAluminum foilOld bath towel

1To make a Worm Worldfor earthworms, youwill need to construct a

vertical box that is open atthe top and covered on oneside with acrylic. Begin bycutting your carton down tosize: Cut the top part off sothat you are left with a boxthat is 4" deep. 'f thebottom of the box happensto be exactly the same sizeas your picture frame, great!Go on to Step 3. If not, you

will need to cut the boxdown some more.

2Measure your acrylicsheet or plastic box-style picture frame.

(Be sure to use the insidedimensions of the frame.)Now draw dotted lines onthe bottom of the boy tomatch the dimensions of thepicture frame, measuringfrom 1 corner of the box Cutalong the dotted lines, asshown in the illustration. Youwill have three pieces of thebox when you are done. PartA is the main part of theWorm World. Part B will formthe other side of the WormWorld box Part C can bethrown away. By fitting A andB together and letting themoverlap, you will have recon-s.ructed a box, nat will be11" by 14"and open onone end. Tape or staple Aand B together to make thebox stronger When you aredone, you sho,Ild have a boxthat is open on top andopen at one enc'

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3Now you wi:1 need tomake the box water-proof. Line the bot-

tom and sides with a plasticgarbage bag, and tape thebag in place using duct tape.Don't open the garbage toe3

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up; use it as a double layer.Be sure the box is com-pletely covered with plasticon all of its inside surfaces.Use plenty of tape to sealthe plastic to the box.

4Place the acrylic pic-ture frame over thebox, to make the win-

dow through which you canview the worms. The pictureframe should fit snugly. Oneend of the box will still bep(-;tly open, but that's allright. That is the top openingfor your Worm World Useduct tape to tape the acrylicto the bcx on three sides.Seal it well. If you are using asheet of acrylic instead of apicture frame, use a doublelayer of tape to make thebox stronger.

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5Stand the WormWorld box on end,with the opening up.

The box is now ready to befilled with layers of dirt. Eachlayer should be about 2"deep. Use alternate layersof topsoil, potting soil,and sand. Or dig some soilfrom two different areasone where the soil is richand black, another where thesoil is light brown. Pack thesoil down firmly as yo, i fillthe Worm World so that thereare no big air spaces. To'<Lep the earthworms fromgetting out, don't fill theWorm World to the top.Leave about 3 inchesfrom the top layer ofdirt to the top of the box.Water the soil so that it isquite moist but not soaking,and keep it wet by sprinklingit every few days.

6Now it's Slime Time:Use a trowel or smallshovel to dig for

earthworms in your yard orit a park. (Be sure to getpermission if you are diggingin a public area.) Be carefulnot to cut the worms in halfor injure them while you aredigging. Handle them care-fully. Place 2 or 3 rood-size

worms on top of the soil inyour Worm World. Add afew rotting leaves on top,which the worms will eat. Ifyou have room, you rraywant to keep the WormWorld outside in a garage orpatio. If you want to keep itindoors, cover the top with apiece of aluminum foil,punctured with small airholes. Cover the whole thingwith an old towel to keepthe Worm World dark.

When you are all donewith the experiment at theend of the month, let theworms goback to theirreal worm world;

HOW TO WATCH WORMSEarthworms are night

crawlers. They move aroundwhen it's dark. By putting atowel over the Worm World,you have created artificialdarkness. When you take thecover off, the worms maycrawl away from the light. Towatch them for a longperiod of time, go outside atnight and use a flashlightcovered with a red balloon.The red light will not disturbthe worms. You can go look-ing for earthworms this wayin your yard or park at nightroc.

0.1

57

WHAT TO LOOK FORLook for the tunnels earth-

worms make through thelayers of soil. How long willit take the worms to mix upthe different layers of soil?

Try to see the worms asthey eat. They will pull arotting leaf partway into theirtunnels and nibble on :t.Sometimes thcy poke thorheads up aboveground andeat leaves. Where are theirtails?

Can you tell which end isthe worm's head? Can youfind its mouth? Are someworms fat and some skinny?Look closely: Does the sameworm always stay the sameshape?

AFTERWORDSNext time you sit down toeat a BLT or a peanut butterand jelly sandwich, justremember this: You shouldthank your lucky worms forall the food you have to eat.Without earthworms, wewould not have the kind ofsoil that we have on much ofthe earth. Without earth-worms, very little food wouldgrow. Earthworms are called"nature's plows" because asthey tunnel through the earth,they mix up the soil layers,

allowing air to get in andmaking space for plant rootsto grow They eat leaves anddecaying animal fragments,which pass through themand then come out as cast-ings. The castings fertilizethe soil, providing food forplants. Without worms, theearth would be too hard,compacted, and lifeless togrow tomatoes or peanutsfor your favorite lunch

When you went diggingfor earthworms, could youtell in advance whether youwould find worms just bylooking at the topsoil? Wasthe soil a rich, black color,loose and crumbly? If so,you probably found lots ofearthworms there. If the soilwas hard and dry, on theother hand, with very littlegrowing in it you probablydidn't find any In some richfarmland areas, you couldfind 1 million worms onevery acre of land! Theseearthworms can turn andch'irn 40 tons of topsoil peracre in a year.

Some people think thatif you cut an earthworm inhalf, it will grow back, orregenerate, the missing parts.Actually, earthworms canregenerate their heads ortheir tails, but only if they are

severed before the first 10segments or after the lastfour. They can evenregenerate their brains!

Did you notice a wide,lightcolored band aroundthe body of the worms inyour Worm World? Thatis called the saddle, orclitellum. Earthworms arehermaphrodites, whichmeans that they are notmale or female but both. Allearthworms can produceeggs and can fertilize eachother, but they cannot fertil-ize themselves. To mate, anytwo earthworms join to-gether at the clitellum, fertil-ize each other's eggs, andthen each one makes an eggcase, which is deposited inthe soil. If your earthwormsdid not have a clitellum,they were not adult worms.Maybe you had TeenageSlime Time instead!

yo1 probably noticedthat even without a cover onyour Worm World, the earth-worms do not try to escapeThat's because they don'treally want to be anywherebut inside the earth. Everwhen they're feeding, wormswill often leave their tailsanchored underground forself-protection That way, if a

robin tries to pull the earth-worm out of its burrow, thewe m can put up a fight.Usually, though, the robin willwin the tug-of-war. Otherburrowing animals such asmoles will dig them out ofthe soil and eat them. Skunksand owls eat earthworms,too. If it weren't for theseenemies, earthworms couldlive to be 10 years old.

Even though they haveno ears or eyes, earthwormsseem to have many senses.They respond to light bymoving away from it andthey respond to vibrations,too In some parts of thecountry, where earthwormsare used as fishing bait, peo-ple use vibrations to driveworms out of the ground!They hammer a woodenstake into the ground andthen beat on it. The vibra-tions are transferred throughthe soil and the worms sensedanger.

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SOLAR COOKERIf it's so hot outside you'reroasting, stop! Don't let thesun roast you. Let it roasthot dogs and marshmallowsinstead! It will take about45 minutes to cook up yourown sun-powered ovens.

YOU WILL NEED

Empty mixing bowlAluminum foilFlexible piece of cardboard

about 8" by 14"Piece of string 3 feet longScissors

Empty round .oatmeal box,with lid

Marshmallows3 long forks or long, pointed

sticks

Hot dog

Did you know that on a clearday the summer sunshine isactually hot enough to cookmeat outdoors? It's true. Andthz yukky truth: When you sitin the sun trying to get a tan,you're really cooking yourown skin!

No one wants a roastedkid for lunch, so wear sun-screen when you're outsidefor long periods on a brightsummer's day. (And don't befooled by cloudy weather:The sun's rays can still pene-trate and leave you with abad burn.) Instead, let the sungo to work cooking E, reallydelicious lunch hot dogsand marshmallows preparedin your very own solar cooker!

1You can make threedifferent solar cookersand then have a marsh-

mallow-roasting race to seewhich one works fastest. Forthe first solar cooker, all youneed to do is line the insideof a large mixing bowl withaluminum foil, shiny-side up.(You may want to try two orthree different bowls to seewhich one works best.)

For the second solarcooker, you need apiece of cardboard thin

enough to bend. (The backingfrom a legal pad works well.)Cover one side of the card-board with aluminum foilagain, shiny-side up. Thenbend the cardboard into asemi-circle, with the foil onthe inside of the curve. Usestring to tie the cardboard inthis position, as shown. This iseasier to do if you wrap thestring around twice and tiethe knot in back.

3Solar cooker No. 3 isreally a hot-dog cooker,but you can also use

it in the Great Marshmallow

Toasting Race. To make thecooker, cut a long windowin the side of an empty cylin-drical oatmeal box. Line theinside of the box with alumi-num foil. (Don't forget to putthe shiny side up!)

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4Now it's cook-out time!But before you go out-side, remember these

rules: Never look directlyinto the sun! And be carefulwith the concentrated spotsof sunlight your solar cookerwill gather. Concentrated sun-light can burn your skin. Also,don't look directly at anyglaring or bright spot onyour solar cooker.

Outside, set your threesolar cookers in a bright,sunny spot. Try to aim them sothat the sun is falling directlyon the foil. Then put onemarshmallow on the end ofeach long stick or fork andthe race is on! The trick totoasting the marshmallows isto find out where the reflectedsun's rays are crisscrossing.

For each cooker, this hot spotwill be in a different place.

Hold your hand overthe bowl, and bring it down

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slowly into the bowl until youfind the hot spot. But don'tleave your hand there formore than a few seconds!

For the bent cardboardcooker, you will probably findthe hot spot somewhere nearthe center of the string orjust ins, ie the string, closerto the foil.

The hot-dog cooker isdesigned to hold a hot dogon a stick inside the oatmealbox. So put your marshmallowon a stick and hold it in thecenter of the box.

Which cooker won therace? Can you figure out whyone cooker works better thananother?

AFTERWORDS

The sun gives out a fantasticamount of energy each day.If you could gather up all thefuel on Earth all the gas, oil,arid coal and burn it fastenough to give off as muchheat as we get from the sun,all of the fuel would be usedup in three days.

Fortunately, we are notabout to use up all of the fuelon Earth in three days. But

Americans do use about 2,000times as much energy todayas the Colonists used in 1776.This is partly because the

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population has grown quitea bit since then, and partlybecause we continue to re-quire more and more energy.We use about 25% of our en-ergy to run cr.rs and another25% at home, i,br heating andelectricity. Industry uses about20% in man.ifacturing steel,automobiles, and other con-sumer goods. And that stillleaves 30% and guesswhere that goes? Into makingenergy! After all, it takes fuelto do things like mine coal,drill for oil, and transport rawmaterials to the refineries.

Strange as it may seem,all of the fuels on Earth comefrom the sun in one way oranother. Here's how it works:Plants use the sim's energy tomake their own food. Animalsand people eat the plants.When plants, animals, andpeople die, the decaying pro-cess eventually after millionsof years produces what wecall fossil fuels: coal, gas, andoil. They were formed frompressure and heat on deadplant and animal remains. In-directly, the sun has providedall of the energy we use.

But now that we are usingso much more energy, someexperts estimate that all of ourgas, oil, and coal will be gonewithin 500 years. That's whypeople are turning to solarenergy as an important alter-native. Several different wayswere developed to harnessthe sun's power and pit itto work on Earth. Your solarcooker demonstrated onemethod: concentrating thesun's rays into a smaller area.This is a great technique forcooking, but to heat a largearea like a house or swimmingpool, it's more efficient tocollect the sun's energy andstore it until you need it.Maybe you've seen houseswith solar panels on the roof.First the sun warms the panelsup. Then the hot panels warmup some pipes just under-neath the panels. Liquid in thepipes flows down into thehouse and warms a tank ofwater. A fan blows the warmthfrom the water into the airducts to heat the house.

The biggest problem withsolar collectors, like the roofpanels, is that the sun has tobe shining for them to work.On Earth, the sun isn't alwaysvisible. But out in space, the

sun is always burning bright!Scientists have imagined thata solar power station couldbe constructed in space, usingmiles and miles of solar cells.When light strikes a solar cell,it starts an electrical currentflowing. In the solar-powerspace station, the electricitywould be converted to micro-waves, and then sent to Earth.On Earth, the microwavescould be changed back intoan electrtal current and sentto you through ordinarypower lines.

So until th' sun burns outin about 20 billion years

you'll have enough poweraround to at least toast amarshmallow!

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SUPER SI WSFaster than a speeding bullet,more powerful than a loco-motive, able to leap tallbuildings in a so igle boundIt's a bird, it's a plane, it'sSuperstraw! Superstraw? Yes,that device that allows you toslurp soda can be used todefy gravity and support athousand times its weight! Itshould take about 30 min-utes to build these superstraw structures.

YOU WILL NEED

1 Box of soda straws (notthe flexible type)

A few large paper clips1 Pound of 1" nails or mar-

bles, or any objects ofuniform size that canbe counted

Roll of plastic or maskingtape

6 Or more cardboard cups,or empty soup cans

1 Tube of hobby glueScissors

1 Box of straight pins1 Raw potato

2 Scraps of wood (V?" to 3/4"thick) the same size asthe sole of your foot

1 0 .7)

64

Gravity is pulling us down-ward all the time. But we'renot alone. Gravity pullseverything on the Earthdownward toward its center.Even air, although it is invisi-ble, has weight and is a realsubstance, like a solid or aliquid, and is acted upon bythe forces of gravity. As amatter of fact, there is about15 pounds of air pressure oneach square inch of surfaceat sea level! So why don'tbuildings collapse andbridges fall into the watersbelow them? Because we'velearned how to deal withgran qty. We know how to usethe opposing forces that ex-ert a push against gravity.

By using straws and afew other items, you ca' , see

how the forces of gravit,workin the mriaturebridges you will build andthen in the great spans ofreal bridges on which youride or walk. Also, see howthe lowly straw can dispersepressure and can hold up aweight many times its own.

Imagine one of the first,

most primitive bridges manever encountered. It wasprobably a log fallen acrossa stream and aver which oneor two people could walkat a time. Today's bridgesspan great rivers and bays,often for many miles Thesebridges hoid tons of vehiclesand passengers at one time,efficiently and safely. Yet, thebasic principle is the same:The upward supportingforces must be greater thanthe downward pull of gravity

1Let's make a 1-log typeof bridge by using 1straw and see how

much of a load it can ca. ry.First, make supports bystacking up two piles of

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books so the height of eachpile is equal to the other.(You can also use two chairsplaced almost together ortwo table surfaces.)

Slip the straw throughthe loop of the paper clip.Place the ends of the strawbetween two piles of books.Attach a paper cup to theclip (tape it, if necessary)and begin putting nails intoit or wrap tape around soupcan twice (near top rim) andthen slip the paper clipthrough, for a hanger. Howmany nails does it take tobend the straw? How manyto make the straw collapse?Use extra paper clips andcups, if needed.

Move the two bookpiles, first closer togetherand then farther apart, andagain .ee how many nails ittakes to collapse the straw ineach of those positions.What difference does thedistance between supportsmake in how much load thestraw can carry?

2Tape another sodastraw to the first onewith the paper clip.

You've made a beam. Sus-pend this between the twobook piles. Again, hang thepaper clip and paper cupfrom the beam. Add nails tothe clip.

How many nails does ittake to make the beam col-lapse? Does the doublestraw or beam constructioncarry more or less

when viewed from one end,a triangle is formed. Tapethem together.

Suspend the paper clip

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this will carry.Build another

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than twice the loadof a single straw?

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three straws together as wellas taping them Let dry andagain determine how strongthis one is This is called alaminated beam

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Make your own GreatBridge Place the two

dm Piles of books 1 straw-iength PLUS another 1/2 straw-length apart. Use straws,tape, glue, scissors and evenstraight pins to make a strongbridge that will span the

distance between the twobook piles. You might wantto connect soda straws bysliding one inside the other.Remember also the strengthin the triangular bear.

What is the greatest loadit can carry before collaps-ing? Use the nails and cupsand/or the metal food cansto find out.

5Build a small, strongbridge with as fewstraws, glue, and tape

as necessary, but one thatcan still support a heavybook. Place the two piles ofbooks 11/2 straw-lengths ap-art. Which bridge formationsupported the book'sweight?

6Have you ever tried topush a straw through araw potato? It is al-

most impossible, isn't it? Butif you take that same strawand hold one index fingerover one end of the strawand jab the potato with oneswift stab of the other endof the straw, it will sink rightinto the potato. Surprised? Itworked because, by holdingyour finger over the end ofthe straw, you trapped the airinside and the pressure wasconcentrated in the straw.

1 0 3

With all that pressure on onepoint, the straw took on astronger force. Now let's usethis same pressure idea, b.itlet's spread it around.

Would you believe that asingle straw can supportyour body's weight? Try this:Use sharp scissors to cut astraw into smal! pieces, eachabout Y4" long. Make eachpiece the some length. Gluethese pieces upright on apiece of wood about as bigas the sole of your shoe. Tryto space them equal dis-tances apart and let the glueharden. Lay another piece ofwood about the some sizeover the tops of the strawpieces. Put one foot on topof the upper board andgently shift all of your weightonto the board. Have some-one look between theboards. Do the straws col-lapse? How much weig"4can the straw pieces supportif you put them closer to-gether? Get more pieces todo this. Hovv. much weightcan the straw pieces supportif you make them longer?Shorter?

ARERWORDS

Just as your skeletal system(along with your muscularsystem, of course) holds you

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up, the skeletal system of astructure such as a bridgekeeps IT up. Any bridge orstructure you see has twokinds of forces acting uponit. One force, gravity, is pull-ing down toward the centerof the Earth. The skeletal orstructural system of thebridge is c.)unteracting thatforce, exerting an upwardforce to keep it from collaps-ing. in your first experiment,the straws supported be-tween the book piles werebeing pushed "up" by thesurfaces of the books, whilethe cup of nails was trying topull the straw bridge downtoward Earth.

Did you notice that thestraw was not absolutelyrigid? Part of the downwardforce helped change theshape of the straw: It saggedat the middle with theweight of the cup full ofnails. Just how much itbends at the middle de-pends partly upon how farthe middle of the straw isfrom its supports The fartherthe middle was from thebook-pile supports, thegreater the bend (or distor-tion) of the straw

Two straws side by sideshould have been able tocarry twice as much load.

But a beam made of threestraws, and especially whenglued together tightly, madea much stronger structure Atriangle was created in whichthe load carried by any -,rrstraw was more easily snaredwith the other two. In build-ing construction, a beam thatis made up of a number ofsmaller pieces fastened to-gether is called a laminatedbeam. Laminated beams canhold more than the sum ofeach of their individual parts

Surprised that one straw,cut into small pieces andplaced on end, could easilycarry your body weight? Ifyou sat in a bucket hungfrom one soda strawstretched between two ta-k.,:es, it wouldn't i iold you!This is because of pressurethe force pushing dawnon a surface

You can spread a largedownward force over 3 smallarea, especially if you havemany small areas. If you stepon one nail sticking up out ofa board, it could go rightthrough your foot. The forceof your body weight is con-centrated on the tiny area atthe, point of the nailterrificpressure! Have you ever seensomeone Iving on a bed of

nails? The many nails are

close together so that no onenail is given enough pressureto puncture the skin. But becareful getting up and lyingdown!

The skeleton of a sky-scraper has several verticalcolumns of steel. These col-umns carry all of the weightof the building and act justlike the small pieces of strawthat were glued upright. Be-cause they carry the loadvertically, there is very littledistortion of the columns.

Whet you built the GreatBridge, you might have useda number of triangles. M-angles can share loac moreeasily than squares or rec-tangles. The triangular partsof a bridge have the someadvantages in carrying a loadas did your three straws fas-tened together. The famousAmerican architect Buck-minster Fuller pioneered theuse of triangles in buildings.He called his design ageodesic (earth-shaped)dome. Your public librarywould have a picture of one.Perhaps you could try build-ing one with straws Imaginehow it would be to live insuch a house!

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111K 'EN BOTANYKitchen Botany is a goodactivity to begin about anhour before dinner. After youare finished, eat the less sweetproduce with a dip. Eat thesweet produce with fonduefor dessert. Recipes areincluded.

YOU WILL NEED

At least one of tne follcwingfrom each group:

Cucumber, zucchini,watermelon

Apple, pear, quinceTomato, grape, blueberryPlum, cherry, peachCarrot, celery, parsnipOnion, garlic, shallot

Cabbage, cauliflower, broccoliCutting boardKnife

Magnifying glass (optional)Ingredients for Dip and

Fondue (optional)

Have you ever eaten a flower?What plant parts do you eat?A tomato is a vegetable isn'tit? This activity deals with fruitand vegetables you eat allthe time. They will help youanswer these questions. You'lltake a look and then take ataste. And then you can growyour own garden with what'sleft over.

1Put all of the produceon a table. Place all

fruits in one pile and allvegetables in another. Howdid you decide which pile toput each piece in? Was yourchoice based on color or taste?Was it based on the section inwhich each can be found in agrocery? None of these thingswill help you separate thefruits from the vegetables.The following will.

3Examine each halfcarefully. Use a magni-fying glass if you have

one. If you find seeds or pitsinside, the piece of produceis a fruit. If there are no seeds,it is a vegetable. Reclassify,

or regroup, your produceinto separate piles of fruitsand vegetables.

2Place a cutting boardand knife on the table.Being careful with the

knife (or ask an adult to help),cut each piece of producein half crosswise.

4Eat the vegetables witha dip as an appetizerbefore dinner, or put

them in the refrigerator forlater use in cooking.

5Line up the fruit on thetable. Fruits come in allshapes and sizes. They

can be mushy or crunchy,with seeds or with a pit. Thereare names that describe these

differences. Try to matcheach piece of fruit with itsdescriptive name.

Pepo (PEEP-o): a fleshy fruitwith many seeds inside anda harder rind outside.

Pome (like ROME): a fruitwith a hard covering aroundits seeds.

Berry: a pulpy fruit that hasmany seeds.

Drupe (DROOP): a fruitwith a hard pit that coversone seed.

6Refrigerate the fruits,or eat them for dessertwith honey or cream

or chocolate fondue. Savesome seeds to grow yourown houseplants.

68

FONDUE

Melt one package of choco-late chips in a double boiler.Ask an adult to show you how.Dip the fruit in it with forks.

If chocolate is somethingyou avoid, serve the fruit withseveral kinds of cheese.

DIP

Mx one package of driedonion soup mix with one 16-ounce container of culturedsour cream. 0'41 beforeserving. VARIATIONS

Some fruit seeds and vege-table parts can be used togrow beautiful plants.

Plant orange or other citrusseeds in potting soil and waterthem. Keep them in a warmplace until seedlings develop,then move them to a sunnyspot.

Apple, peach, pear, andplum seeds need a coldperiod before they will grow.Scratch the seeds with sand-paper and plant them in plantmoss and keep them in therefrigerator for about twomonths. Then plant themin potting soil and watchthem grow.

Make hanging planters fromroot vegetables such as car-rots, beets, turnips, etc. Cutoff the top two inches of thevegetable. Scoop out thecore. Hang the plant upsidedown by putting toothpicksinto the vegetable and rang-ing it with a string. Keep the

scooped-out hole filled withwater. You may have to fill itseveral times each day. Greenleaves will grow out from thevegetable top, up and aroundyour "planter':

AFTERWORDS

When you divided yourproduce into fruits and vege-tables, you were classifying it.

Classification is the act of sort-ing objects by certain rules,or criteria. When you sortedyour produce, the criterionwas that all produce withseeds is fruit. Classification is

an important scientific tool.People who study plantsknow that plants with similar

11;

flowers, fruits, leaves, orgrowth forms are often related.Just like people, these relatedforms are groupc into families.

The squash fay 'lily includes

cucumbers, pumpkins, water-melons, cantaloupes, andgourds; it also includes sum-

mer squashes such as zucchiniand winter squashes suchas acorn. These fruits grow onvines with five-sided stemsthat creep along the groundor climb by wrapping theirsmall tendrils around otherplants, fences, etc. They havefairly large leaves, oftenshaped like maple leaves. Wegenerally eat only the fleshyparts of the squash familyfruits, but cucumber andzucchini are eaten flesh, seeds,rind and all. There are evenrecipes for fried squash blos-soms and squash blossomsoup in some cookbooks.

The tomato family is some-times called the nightshadefamily. Some nightshades,like the deadly nightshadeof Europe, are extremely poi-sonous. Its more tasty familymembers include tomatoes,potatoes, peppers, and egg-plant. Appropriately, tobacco

also comes from this family.Members of this family usuallyhave flowers with five petalsand fruit in either a pod orberry with many seeds.

The rose family includesapples, cherries, strawberries,pears, plums, almonds, andpeaches. Members of the rosefamily can be as small as a

rosebush or as large as a tree.Their flowers commonly haver rye rounded petals. Rose hips,high in vitamin C and oftenused in herbal teas, are thefruit of a rose flower much likethe ones seen in gardens. Inancient times, the rose wasused medically. It was a favor-ite of the Romans, who spreadits culture wherever theirarmies conquered.

Vegetables are also classi-fied into families. Membersof the mustard family includebroccoli, cauliflower, cabbage,radishes, turnips, brusselssprouts, kale, horseradish,and mustard plants. Membersof the mustard family aresometimes called crucifers(KROOS-i-ferz), from their Latinname, which describes thecrossshape of the four petalsof the mustard flower. Themustard that we spread on

sandwiches is made fromground mustard seeds mixedwith vinegar or oil and spices.While most mustard plants arefairly small, the black mustardplant of Palestine can growup to 12 feet tall and havebirds singing in its branches.Even a phenomenon like thatdoes not defy classification.

70

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ALIENSIs there life in outer space?

Will alien beings ever come toEarth? Scientists have several

methods of finding out andhere's one way. It will onlytake you 30 minutes to set upthe experiment, but you maynot see results for severalweeks.

YOU WILL NEED

4 Empty jars with lidsHot waterMeasuring cupSaucepanUnflavored gelatinSpoonPen or markerPaper

Tape

Scissors

String

Extraterrestrials...alien Re-forms... little green kids fromouter space. Are they outthere and, if so, what dothey look like? What if the aliens aren't large visible beingsthat walk and talk? What ifthey are too small to beeasily seen?

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That is the problem scien-tists had to deal with in the1960s and '70s, when theViking spacecraft was beingdesigned to land on Mars.Scientists needed a way todetect any life-forms--eventiny, microscopic ones, likebacteria. One of the experi-ments designed for the Vikingproject was called Gulliver. Inthe Gulliver test, "sticky" stringwould be dragged acrossthe surface of Mars. Then thestring would be put in a con-tainer with "food,' so that ifany life-forms were stuck tothe string, they would benourished and grow.

You can try a version ofthe Gulliver experiment your-self here on Earth. Who knows?Maybe you'll find life-formsin places yo'i never even sus-pected could sustain lifemaybe in your closet or underyour bed!

1First, you will needto sterilize your jars, toremove any life-forms

(germs, for instance) that arealready there. To do this, wash

the jars and then pour boilingwater into them. The jars willbe hot, so don't touch themnow. Let them stand untii theyare cool Sterilize the jar lids inthe same way, by pouring boil-ing water on them. Be verycareful when using the stoveto boil water. You may wantto have an adult help youwith this.

2Measure 2 cups of veryhot tap water into asaucepan. Add one

packet of unflavored gelatinand stir until the gelatin iscompletely dissolved. Youmay need to heat the waterand gelatin over low heat tohelp the gelatin dissolve. Pour1/4 cup of gelatin into one ofthe jars and screw the lid ontight. Label the jar "control:'Then pour 1/4 cup of gelatininto each of the other threejars.

3Cut 3 pieces of string,each about 15 incheslong. Dip one of the

pieces into the remaining

11

gelatin in the pan and leaveit there for a minute, until thestring is soaked. Then take thestring ar .d drag it across thefloor somewhere underyour bed, across the living-room rug, across the basementfloor, or wherever you like.Put the string into one of thejars and screw the lid on.Label the jar with "Rug" or"Basement" or wherever thesample came from. Soak theother 2 pieces of string in gela-tin and go ou&de to repeatthe experiment. You mightwant to drag one of the stringsacross the grass or dirt andthe other across the sidewalk.Label these samples, afterputting each into a jar, andput the lids on both of them.

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4Now, wait and watch.Check your jars forlife-forms every day.

It might take two weeks ormore before you see a changein the gelatin or on the string.And remember: The life-formsyou are looking for are tiny,like bacteria. They probablywon't grow into big, uglygreen blobs! But the important

72

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thing is that you're discoveringlife-forms where you didn'tthink they existed!

Is there anything happen-ing in the control jar? If so,that shows you that your jarshad bacteria in them evenbefore you put the stringsamples in.

VARIATIONS

Leave the sticky string out-side for several hours beforesealing it in the jar.

Punch holes in the lids of thejars so that any alien beingspresent will have an air supply.

273

Use a string ;caked in applejuice and a string soaked ingelatin to collect life-formsoutside. Leave them both inthe sun for an hour or so.Does the apple juice attracta life-form different than thekind attracted to the gelatin?

WHAT IS A CONTROL?

Whenever you conduct ascientific experiment, you areasking a "what if" question.For instance, you might ask

"What will happen if I pile726 cement blocks on mybicycle?" The answer is thatthe bike would be crushed!If you actually tried this experi-ment, you wouldn't need a"control," because you wouldhave no doubt that the resultscame from only one cause:the cement blocks!

But for some experiments,

you can't be sure what is caus-ing the results. For instance,this month you are asking

"What will happen if I dragsome string on the groundand then seal it in a jar withgelatin?" If something starts togrow in the jar, are you sure itcame from the string? Or didsome life-forms fall into the jarwhile you were dragging thestring around? In these cases,you need to set up two sam-

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ples. You do your experimenton one of the samples, andleave the other samplethecontrol ak-ne. If the resultsyou were looking for occuronly on the experimental sam-ple and not on the control,then you know exactly whatcaused the results.

AFTERWORDS

Searching for life on Mars orany other planet is a lot moredifficult than you might think.For one thing, scientists must

make sure that they don'tcontaminate the planet theyare visiting by bringing alonglife-forms from Earth. When theViking mission was launchedin 1975, both of the space-craftsViking 1 and Viking 2

had to be entirely s*erilizedto kill all bacteria or othermicroorganisms that might bepresent. Can you imaginepouring boiling water on aspaceship? Actually, the Vik-ings were heated to 235°F,then sealed inside a shieldto keep out microorganisms.

Landing on Mars wasn'teasy. On Earth, parachutes are

often used when we want todrop people or objects out ofthe sky and land them safelyon the ground. But the atmos-phere on Earth is very densecr mpared with the atmos-

phere on Mars. That meansthat when parachutes openabove Earth, the atmosphereis "thick" enough to pushagainst the parachute materialand cause it to slow down.On Mars, the atmosphere isso thin that it doesn't createmuch resistance. To jump outof a plane above Mars, you'dneed a very big parachute!

To solve this problem andhelp the Viking lander get fromthe orbiter to the surface ofMars, scientists decided to usea combination of parachuteand rocket engines. The rock-ets would help the lander setitself down gently. Unfortu-nately, the rockets themselvesposed a new problem, be-cause they tended to blowthe soil in every direction.Scientists wanted to be surethe lander didn't mess up thesoil directly surrounding thelanding area, because thatwas the soil that would besampled for the biology tests.Eventually, a better design forthe rocket engines was found.

Did scientists find evi-dence of life on Mars? Theresults were mixed. Biologistsgenerally agree that life-formscan be detected three ways:(1) You could look for evi-dence that some kind of foodhad been produced; (2Wpp

could look for evidence thatfood had been consumed;and (3) you could look forchanges in the atmosphericgases which is another wayof saying that someone,or something, is breathing.(On Earth, atmospheric gaseschange when plants give offoxygen or when peopleexhale carbon dioxide.)

Although scientists didn'tfind any signs of food beingproduced, they did discover,during several experir ,ents,that atmospheric gaseschanged quite a bit. However,the changes were not neces-sarily the kind that would indi-cate the presence of life-forms. Other experimentsshowed results that couldeasily have been caused bythe presence of microorga-nismsor could have beencaused by strange chemicalreactions on the planet. Andwhen the Martian soil wasfinally analyzed, no organicmolecules were found.

So what's next? Anothertrip to Marsor maybe to thatgreat, gassy planet Jupiter?Someday, you may be onboard when another stickystring is cast into the vastuniverse, in search of aliens.

74

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LAWN P ERThe amount of time it takesto make Lawn Paper dependsupon the drying method youchoose. The paper itself canbe prepared in about twohours.

YOU WILL NEED

Grass clippings(about one handful)

Scissors, measuring cup,paper towel

Blender or food processorWater, newspaperPiece of window screen

(about 5" x8")Dishpan or tub or sink!ron (optional)

Here's something to dowith grass clippings that youprobably never thought of:Make paper! Even thoughmost of the world's paper ismade from wood, many plantmaterials can be used: cotton,celery...even grass clippings.So grab a handful, and try it!

Use the scissors care-fully to cut the grassinto pieces about 1/4"

to 1/2" long. You will needabout one cup of choppedgrass. Put the grass into theblender.

Cut a paper towel into 1/4"pieces. Put the pieces in theblender with the grass.

76

Add three cups of waterto the paper and grass in theblender.

2Blend the grass-paper-water mixture (calledslurry) for three to five

minutes or until it feels softand smooth. Keep a closewatch on your blender. If thegrass is too long or there isn'tenough water, your blendermay have to work too hardand it will overheat. Add extrawater so the grass doesn't getcaught in the blades.

3Pour off the excesswater from the slurryand throw it away.

Put the screen into thedishpan or sink.

Slowly pour the slurry ontothe screen in a thin, even layer.Use your hands to gently patdown, smooth any lumps,

and fill in any holes. Flattenthe slurry on the screen so itssmooth and flatter than apancake.

4Lay newspaper ontop of the slurry. Pick apiece that doesn't have

much dark print or else thewet lawn paper may absorbsome of the dark ink.

With one hand under thescreen and the other handover the newspaper, carefullyturn over the screen, slurry,and newspaper.

5Press down hard onthe screen to squeezeout water. Slowly peel

up the screen so that yourpaper is left on the newspa-per. If the paper sticks to thescreen, keep pressing morewater out of it.

Iii Now keep pressing yourlawn paper with dry news-paper. Press as hard as youcan for a few minutes to flattenthe grass and bind the fibersinto paper.

To dry your paper,you can:Iii put it outside in a

sunny spot.put it in a solar greenhouse

to dry it faster.Iii iron it dry in 10 minutes.Put the iron on the cottonsetting. Protect your paperfrom heat by sandwichingit between layers of papertowels or newspaper.

IWhen it is dry, carefullypeel it away from thenewspaper. Use your

lawn paper for a specialpurpose:

Iii Write a letter to a specialperson.Iii Take a picture of your familyon the lawn or in your park.Frame the picture on a pineof lawn paper.Iii Have a lawn party withlawn-paper invitations anddecorations.

VARIATIONS

Iii Try making paper withdried grass instead of fresh,or cut up the leaves of a treeor shrub. How is this paperdifferent from paper madefrom fresh grass?

Make colored paper byadding food coloring to theslurry. Or try using the news-paper comic pages in Step 4.They will also add color.Iii Be fancy. Press a dandelionor other pretty weed into thewet paper before pressingand drying.

12"

Be creative. Shape the slurryon your screen into a shape,such as a dragon or a flower.Find things on your lawn touse as eyes and other details.Then press and dry it.

AFTERWORDS

Paper is a surprisingly recent

invention. It was created lessthan 2,000 years ago by theChinese. Conquering Arabsdiscovered this Chinese paperin 704 A.D., but it wasn't untilabout 600 years ago that pa-per came into common use inthe West. In the Middle Ages,reading and teaming wereencouraged. This increasedthe demand for paper. As thedemand increased throughthe centuries, the quality ofpaper was improved by ex-perimenting with differentraw materials.

Today, paper is madefrom cellulose pulp, which isfound in all plant tissues and

fibers, Fibers are thick-walledplant cells that support planttissue. They are hollow tubesabout %" long and thinnerthan a hair. These tubes are re-organized to form thin sheetswhen paper is made. Thesethin, long cells give paper itstoughness and flexbility.

Although any fiber maybe used to make paper, cer-tain fibers make higher qualitypaper than others. Linen isan excellent material forpaper because its fbers havenotches that help them stickto each other. Grass and strawhave short, smooth fibers thatcannot make strong papersalone. Adding other fibers,such as those in paper towelsand newspaper, to grassfibers makes the lawn paperstronger. That is becausepaper towel and newspaperfibers are less smooth thangrass fbers and help in bind-ing the reorganized fibersinto paper.

Today, about 95% of theworld's paper is made fromwood pulp, and there areabout 12,000 types of papermanufactured. We use paperproducts every day. An aver-age family discards one ton ofpaper each yearthe amountof paper produced from 17trees. That is a small forestevery few years! Because ofthis, recycling centers havebecome valuable coordina-tors for the re-use of wastepaper. Not only does recy-cling save trees, but it alsouses 30% to 40% less energythan producing paper from

new wood pulp. Try recyclinga piece of your own lawnpaper to prove this point.

Grass is almost every-whereso why isn't grassmade into paper? Grass isgrown in wide-spread areasand the crop is bulky. Trans-

portation costs alone makelarge-scale grass paper pro-duction more expensive thanwood-pulp paper production.Also, the grass supply and itsprice vary from year to year.Sc grass paper production isheld back by the difficulties ofgrass supply, rather than byany technical difficulties. Thesedifficulties don't have to stopyou. As long as you have anearby lawn, park, or grassytraffic island, you can produceyour own lawn paper.

1

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IRise and shine! It's time tofind out what makes breadrise. You'll need at least 4hours to get from mixing tobaking to eating. In themeantime, mmm-mmmwhat a wonderful smell!

YOU WILL NEED

2 Large drinking glasses2 Packages active dry yeast1 Tablespoon sugarAll ingredients for Good

White Bread, as listed inrecipe

Large and small bowlsMeasuring cupsSmall saucepanWooden spoon (or hand-

held or electric mixer)Kitchen utensilsPlastic wrap9" by 5" by 3" Loaf panPot holders or oven mitts

EXPERIMENTING WIThYEAST

What does yeast actually doand how does it make breadrise? To find out, try this easyexperiment. In a large drink-ing glass, mix 1 package ofactive dry yeast and 1/2 cup

1 3 l;

10 FINof very warm water (100° to115°F.). Label this YEAST. Stir

well to dissolve the yeast. Inanother glass, mix 1 packageactive dry yeast, 1/2 cup verywarm water, and 1 table-spoon sugar. Stir well. Labelthis YEAST AND SUGAR. Setboth glasses in a warm spotand watch what happens.Within 10 or 15 minutes, youwill know which yeast mix-ture is producing a gascalled carbon dioxide. Thatgas ss what makes bread rise.Keep this experiment for sev-eral hours and watch to seehow long the yeast keepson working, making carbondioxide bubbles. Whathappens when the yeastruns out of gas?

MAKING BREAD

1Make sure that youhave oermission touse your stove and

oven. You may need anadult's help. Take the middlerack out of the oven. Preheatoven to 400° (375° if you areusing a glass baking pan) andassemble all the ingredients

for the Good White Breadrecipe.

INGREDIENTS FOR GOODWHITE BREAD

1 Package active dry yeast*1/2 Cup very warm water

(100° to 115°F)

2 Tablespoons sugar4 Tablespoons (1/2 stick)

melted butter11/2 Cups warm milk1 Tablespoon salt5 to 6 Cups unbleached or

bread flour*For an even fluffier loaf, try

2 packages of yeast.

In a small bowl, combinethe 1 package active dryyeast and A cup very warmwater. The water should be10C° to 115°it will feelquite warm but not burninghot to your fingers. Stir well.When the yeast is mostlydissolved, add 2 table-spoons sugar. "Proof" theyeast by letting the mixturesit for 5 to 10 minutes. It willstart to bubble and foam likeyour yeast-and-sugar experi-ment. If it doesn't foam up,

1 1)1 i _L

either the water is too hot orthe yeast isn't fresh.

2WI-ile the yeast isproofing, melt 4 table-spoons butter and

add it to 11/2 cups warm milk.Stir in 1 tablespoon salt. Nowyou will begin adding flour.All together, yol, will proba-bly need 5 of 6 cups flour, ormore. Start by adding 3 cupsflour to the milk-and-buttermixture, and stir with awooden spoon, or with ahand-held or electric mixer.Then add the yeast mixtureto the dough and mix wellfor 1 minute. Add 2 morecups of flour, or enough tomake the dough pull awayfrom the sides of the bowlYou may need to add all ofthe flour. The dough shouldnot be too sticky because inthe next step you are goingto knead 1.

3Turn the dough o' itof the bowl onto afloured board or

floured countertop andknead it until it is smoothand elasticfor about 5 to

80

10 minutes. To knead thedough, push into the doughwith your fist or with the heelof your hand Then fold thesides of the dough over andrepeat the process. Turn the

dough frequently as youknead it. Keep adding flourto the board and to thedough if the dough gets toosticky. When the dough issmooth and elastic, divide itinto two equal pieces. Puthalf the dough in a clean,buttered bowl Turn it over

once or twice to coat it withbutter. Cover dough withplastic wrap and let it risein a warm place until it is

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double in bulktwice itsoriginal size. This may takefrom 1 to 2 hours. Check itfrequently.

4In the meantime, but-ter the inside of a 9"by 5" by 3" loaf pan.

Put the other half of thedough into the loaf pan andbrush the top with water.Bake it immediately--with-out letting it riseon thelowest rack in a 400° oven(375° if your loaf pan isglass). Bake for 40 minutesand then check it by care-fully knocking on the bread.(Use pot holders to pull thepan from the oven.) If thebread sounds hollow, it'sprobably done. You shouldalso carefully turn the loafout of the pan and knock onthe bottom, to make sure itsounds hollow too. Allowthe bread to cool on a rack,and then slice it and try it.Even though it hasn't risenmuch, you can still eat it.How does it taste?

5Wash the loaf pan andbutter the insidesagain. Now check on

the dough in the bowl.When it has doubled in bulk,punch it down. How longdid it take for the bread to

1 3 .'-

rise? Is it more or less timethan it took for your yeast-and-sugar experiment to fillthe glass with foam? Turn thedough out of the bowl andknead it again for 3 or 4minutes. Shape it into a loafand pt.,* it in the butteredpan. CL _r with plastic wrap.Allow it to rise a secondtime until it is double inbulk. Brush the top withwater. Bake it on the lowerrack in a 400° oven (375° forglass pans) for 40 to 45minutes. Knock on the loaf,as in Step 4, to see if it'sdone.

Most bakers say thatbread should cool com-pletely before you slice it.But who ran resist hot,freshly ed bread? Howdoes it taste, compared withthe first loaf of bread thatwas not allowed to rise?

AFTERWORDS

Yeast is a microscopic plo itthat can change sugar intocarbon dioxide and alcohol.This process is calledfermentation. In your first ex-periment, the yeast con-verted the sugar-water tocarbon dioxide, and yousaw tne glass fill up with

foam. The foam is actuallymany tiny bubbles of carbondioxide gas. Carbon dioxideis the colorless and odorlessgas we exhale when webreathe.

The rising of bread issimply like blowing up amillion tiny balloons scat-tered throughout thedoughexcept that youdon't blow up the balloons.The yeast does. To makebread rise, you must give theyeast some sugar, and youmust distribute the yeastthroughout the bread doughby kneading it. Otherwisethe bread in someplaces and4,6t in others Didyou find a few large holes inyour loaf of bread? If so, youprobably didn't knead itenough Holes in a loaf ofbread mean that largerpatches of yeast weregathered there, giving off awhole lot of carbon dioxide.

But why does yeast giveoff carbon dioxide in the firstplace? Because yeast is aliving plant and it behaveslike 111 living cells. It uses

oxygen to maintain life.When you take in ox, genand give off carbon dioxide,the process is calledrespiration. Even dandelions

use oxygen from the environ-ment and then give off car-bon dioxide as wastematerial. So why can't weuse dandelions to makebread?

The answer is that mostplants, including dandelions,use up the carbon dioxidethey produce in a processcalled photosynthesisthemaking of food for the plant.Dandelions make their ownsugarthey don't need aglass of sugar-water to helpthem grow. And the carbondioxide produced by thedandelion is used right awayby the dandelion itselfYeasts, on the other hand, arenot green plants and do notmake their own fcc-.1 Theyfeed on other plants andanimals. So the carbon diox-ide they produce is notneeded for photosynthesis. Itis not used up and it can beseen as bubblE in the glass.It can also be used to makebread rise

Another byproduct ofyeast's respiration is alcohol.Alcohol is produced quicklyand in large amounts whenyeast is combined with sugarin a low-oxygen environment.When wine and beer aremade, the yeast is notaerated--not allowed to get

much oxygenand conse-quently more alcohol isproduced Very little alcoholwas produced by the yeastsin your bread recipe, be-cause so much air waspresent when you were mix-ing and kneading the dough.Any alcohol produced wasburned off during baking.

Yeast is what makes beeralca 'lic, and the carbondioxide from the yeast givesthe beer its carbonated orfizzy taste. Some bread reci-pes even call for a can ofbeer, instead of yeast, tomake the dough rise! Again,the alcohol in the beer burnsoff when the bread is baked.

Yeasts are in the air andoften settle on foods that areleft uncovered or unrefrige-rated. Then the yeasts go towork ,:onverting the sugars inthe food into carbon dioxideand alcohol. If you've everleft a jug of apple cider,tightly closed, in the re-frigerator for too long, itprobably became alcoho',c-tasting. Yeast strikes again!

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What's white and sour andcomes with fruit on the bot-tom? A c'rouchy polar bearwho' been tramping aroundin a cherry orchard! Ormaybe the answer isyogurtwhich you canmake yourself. In that case,it's not quite so sour and itcomes with fruit on the top!Allow about 45 minutes tomake a yogurt warming box,and one hour more to pre-pare the yogurt itself. It willtake 7 to 8 hours for theyogurt to "cure."

YOU WILL NEED

Small cardboard box, orinsulated food cooler

6-Inch stack of newspapers6 Plastic trash bags1 Quart fresh whole milkSaucepan

Candy therrnorrieter4 8-ounce c1.4): -)r jarsMeasuring spoonsSmall bowl2 Teaspoons fresh plain

yogurt (check expirationdates for freshr less)

Aluminum foilMasking tape, pen or marker

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INSULATEINSIDE OF

8ox WITHNEhiSPAPERS I1N CLEAN

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What's the difference be-tween yogurt and milk? Justone thing: bacteria. Yogurt ismade with bacteria thatgrow and multiply and causethe milk to "set" into acustardy, creamy, deliciousfood. You can make yourown yogurt for less than halfthe price of commercialyogurtand all you needis a little culture to get youstarted!

1To make yogurt, youwill first need to makean insulated "warming

box" to keep the bacteriahappy. Start with a smallcardboard box from the gro-cery store, or use an insu-lated food cooler. Line thebottom and the four sides ofthe box each with a stack ofnewspapers at least 1" thick.You may want to encloseeach stack of newspapersin a clean plastic garbagebag, to keep everything dryand clean. Make a sixth packof newspapers 1" thick,wrapped in a plastic bag, touse as a lid. If you are usinga food cooler, add somenewspapers anyway, as extrainsulation. Try to leave justenough space inside thewarming box for the number

of cups or jars you planto use.

Place the insulatedbox in a spot where itcan remain undis-

turbed for the next 8 hours.Have the clean cups or jarsready nearby. Heat 1 quart offresh milk (don't use old orsour milk) slowly in a largesaucepan until it reaches180°F on the candy ther-mometer. Pour the milk intothe cups or jars, and setthem close together in thewarming box. Do not fill thejars all the way to the topleave about an inch of roomat the top. Place the candythermometer in one of thejars and check it every fewminutes. When the milk in thejars has cooled to 110°F, itstime to add the yogurt star-ter. It may take 30 to 45minutes for the milk to coolto this point.

3Now you must workquickly. Take 1 table-spoon of milk from

each pint of milk you areusing. If you started with 1quart of milk, you will needto take a total of 2 table-spoons of milk from tl- jars.

It's okay to take 1 tablespoonfrom each of two jars, andforget about the other twojars for the moment. Put the 2tablespoons of warm milk-110°F in a small bowl andadd 2 teaspoons of freshplain yogurt. This is calledadding the "culture!' Don'tuse any more than 1 tea-spoon of yogurt for eachtablespoon of warm milk. Stirit up gently. Now divide thismixture evenly among all fourjars of warm milk in theinsulated box. Gently stir, tomix the yogurt culture inwell. Cover the jars if youhave lids. Place a sheet ofaluminum foil on top of thejars, as an extra cover. Put thetop layer of newspaper in-sulation on as a lid.

Leave the jars in thewarming box un-disturbed for 6 to 8

hours. Then check the yogurt.If it has set, put it in therefrigerator to cool. If theyogurt does not set within 8hours, see the Trouble Spotslist.

TROUBLE SPOTSWas the plain yogurt starter

too oldpast its expirationdate?

Was the milk too hotwarmer than 110°Fwhenyou added the starter?

Did you jiggle or open thewarming box too much dur-ing the eight hours?

VARIATIONSFind out what happens to

the bacteria in your yogurtstarter by adding it while themil!.- still hothotter than110°F You can set up a con-trol led experiment with fourcups of milk. With maskingtape and a pen, label onecup "Plainno starter." Doi l'iadd any starter to this jar.Label the other three jarswith the temperature that themilk was when you addedthe starter. Try adding 1/2 tea-spoon plain yogurt starter to8 ounces of hot milk while itis still 180°F. In another jar,

add the 1/2 teaspoon of star-ter when the milk is 150°F. Inthe fourth jar, add the starterwhen the milk is almost coolenough, say about 115 to120°F Let all four jars sit in theinsulated box. Begin check-ing the samples after fourhours. Did the yogurt made

1 4 ()

with hotter milk set morequickly? How does it tastecompared to the yogurtmade with cooler milk?

Try adding a little morestarter yogurt-1 or 2 tea-spoons pei cup of milktosee how it affects the taste.

Add 1 or 2 tablespoons ofpowdered milk to make athicker, firmer yogurt.

JAM TIMEIf you like your yogurt withsweetened fruit, try addingfew tablespoons of straw-berry jam or peachpreserves to the homemadeyogurt. Mix wel' and enjoy!

AFTERWORDSMaking yogurt might seemlike magic to someone whodoesn't understand bacteria.After all, you simply heat upsome milk, add a tiny bit ofyogurt andpoof!--you'vegot more yogurt! It would begreat if you could do thatwith chocolate.

But yogurt has a secretingredient: bacteria. Whenthe right kind of bacteria areintroduced .o a container of

warm milk, they begin to"feed" on the lactose, ormilk sugar. They use the lac-tose as a source of energy,and change it into lacticacid. That's why yogurt issour, while milk is almostsweet. As the milk becomessour, the protein in the milkbegins to break down and itcoagulates, or sets. That'swhat makes the milk becomefirm, like a custard.

Usually two differentkinds of bacteria are found inyogurt: Lactobacillus bulgar-icus and Streptococcus ther-mophilus. These twobacteria really work well to-gether; they stimulate eachother's growth. But theydon't both grow at the sametime. S. thermophilus growsbetter at lower temperatures,while L. bulgaricus growsbetter at higher tempera-tures. If you introduced theyogurt starter while the milkwas still quite warm, youprobably produced a moresour- or tart-tasting yogurt.That's because L. bulgaricustook over; it produces moreacid than S. thermophilusdoes.

What happened if youintroduced the bacteria tothe hot milk while it was stillalmost 180 degrees ?You ,.robabiy killed the bac-teria! Most bacteria will bekilled at that temperature,which is why you heated itin the first place. You didn'twant to be growing other,possibly harmful kinds ofbacteria while you weremaking your yogurt.

The sourness of yogurtdepends almost entirely onwhich kind of bacteria areallowed to take over whilethe yogurt is fermenting. Tomake a mild, creamy yogurtthat isn't too tart, you needto encourage the S. ther-mophilus to grow Of course,some of that bacteria mustbe present in your starter tobegin with. The problem isthat S. thermophilus doesn'tlive too long in the re-frigerator, so if your yogurtstarter isn't fresh, the bacteriaprobably aren't there.

Yogurt has the reputationfor being a healthy foodand it is. Basically, it has thesame nutritional value as themilk it was made from, butyogurt is easier to digest. Thefermentation processtheprocess of changing milk

sugar into lactic acidhelpsto partially digest some ofthe protein in milk. Yogurtand milk are also both veryhigh in calcium, which isnecessary for your bonesand teeth. But in order foryour body to use calcium, itmust be absorbed in an acidenvironment. Only about20% to 30% of the calciumin milk can be absorbed byyour body. Since yogurt isacidic on its own, the cal-cium in yogurt can be ab-sorbed more easily.

Yogurt is believed to beone of the oldest foods inthe worldand it is eatenby some of the oldest peo-ple in the world. Peopilfrom the Balkan countries areknown for eating a lot ofyogurt, and many of themlive to be 100 wars old!Maybe the yogurt contrib-utes to their longevity, orperhaps some other factorsare responsible. Enjoy yourhomemade yogurt, even ifyou don't live to be 110!

86

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Put together your own pho-tography studio and see whatdevelops! This activity shouldtake you about 45 minutesto complete.

YOU WILL NEED

1 Empty round oatmeal boxBlack spray paint or

poster paintSharp knifeSmall piece of aluminum foilTape, scissors, needle2 Pencils, 1 pen2 Red balloons

flashlightPackage of 5" by 7" single-

weight photographicpaper, #1 or #2 (see Note)

Wristwatch with asecond hand

Important: You will also needall of the darkroom supplieslisted on page 91.

Note: All photographicsupplies are inexpensive andreadily available at amerastores and photographyshops. Do not open thephotographic paper untilyou reach Step 6!

14=

88

ACRE INNSBelieve it or not, you can actu-ally make a camera by simplyputting a tiny pinhole in oneend of a light-tight box. That'show the earliest cameras

worked! You'll be amazedat the sharp quality of thepictures taken with anempty oatmeal box.

diPaint the inside of

an empty oatmeal boxwith black spray paint

or poster paint. Do the sameto the inside of the lid.

2Use a sharp knife to cuta circle about 11/2"in diameter out of the

center of the bottom of thebox. Save the cardboard cir-cle, because you'll need touse it later: It will be the"lens cap" for your camera.

3Cut a square pieceof aluminum foil slightlylarger than the hole

you made in the bottom ofthe box. Tape the foil to theinside of the box so that itcovers t z hole. Be sure tokeep the foil smooth, and tapearound all four sides of the foil

square so that no light can getthrough. Now use a needle tomake a pinhole in the alumi-num foil in the exact centerof the bottom of the box. Thehole should be just a pinhole

no larger.

4Fit the cardboard "lenscap" back into p!aceand tape it so that it

can be opened like a flap ordoor. Tape a pencil along theoutside of the oatmeal box,and tape another pencil paral-lel to the first one, about 2"away from it.

5Before you can loadyour camera, you needto make a "safelight"

a dark-red light that won't ruinthe photographic paper whenturned on in a completelyblackened room. To make asafelight, cut off and discardthe "necks" from two red bal-loons. Stretch the remainingpieces of balloon across theend of a flashlight, one on topof the other, like a double pairof socks.

SiRE'TCH BAL-ODPJ ALROSSEND OF F,A.Stit ,Jr1T oni_ APAIR OF )0C,R5

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6Tee your safelight,oatmeal-box camera,scissors, tape, and un-

opened pack of photographicpaper into a completely darkcloset or bathroom. It is bestto do this step at night andturn out all the lights in yourhouse, so that no light will leakin through the cracks aroundthe windows and doors. Turnon your red flashlight. Remove

the lid from the oatmea! box;make three tape loops (sticky-side out) and set them in thelid. Now you may open yourpackage of photographicpaper. You will see that thephotographic paper is wrap-ped in a black paper lineror envelope, inside the card-board package. Always keepthe photo paper inside theblack paper envelope andkeep the biack envelope in-side the cardboard package.Also remember: Never turnon the room lights until thephotographic paper is putback in its package.

ITake out only one sheetof photographic paperand cut a circular piece

to fit inside the oatmeal boxlid. fhe smoother, shinier sideof the paper is called theemulsion side. Put the circle ofpaper in the lid with the emul-sion side facing up. Press it flat;the tape loops in the lid willhold it in place. Put the lidon the box tightly, and yourcamera is loaded!

8Go outside the nextday and set your cam-era on something solid.

The pencils along the sides ofthe box will keep your camerafrom rolling. If it's windy, youmight also need to steady thebox by putting one hand firm-ly on top. Point the camera atwhatever you want to photo-graph, and open the lens cap.Leave the lens cap open for1 minute if you are photo-graphing in very bright sun-light, 2 minutes on a some-what cloudy day, or 3 minutesif it is very overcast outside.(Note: You may need toexperiment with the exposuretimes. A one-minute exposureon a bright, sunny day worksbest.) While the lens cap isopen, you must not move thecamera!

Jot down a description ofthe subject matter you photo-graph each day. Also writedown the exposure timesthe number of minutes andseconds yOU had the lens capopen. Later, when you de-velop the pictures, you canlook at these notes to findout which exposure timesworked best.

9At night, go into yourdarkroom with the redflashlight, and remove

the exposed circle of paperfrom the camera lid. Put itback in the package of photo-graphic paper Cut anothercircle and load your cameraagain. After you've taken 7 or8 pictures, you will be readyto develop your pictures inthe darkroom part of thisactivity. The instructions forall the darkroom work areorinted on pages 91 and 92.Good luck!

FOR SUCCESS:

Take pictuLs of things thatstand still. If you want tophotoglaph people, they willnave to remain absolutely Fr.111

for 1 to 3 minutes.

If your pictures cor ae outcompletely black, wur cam-era might have a leak. MakeSure the Pd fits very tightly.Also, use shorter exposuretimes.

When loading your camera,do not cut out extra circlesof photographic paper inadvance. Otherwise youwon't be able to tell whichones are exposeu and whichones are unexp ;ed.

You might want to maketwo or three cameras at once.

Then you can take more thanone picture per day.

AFTERWORDS

Believe it or not, the first cam-eras were whole rooms com-pletely sealed off from light,except for a tiny hole in onewall. The light com'ng inthrough the hole projected inimage on the wall oppositethe hole an image of thescenery outside the room.People stood inside thesecamera obso 'ras (the termmeans dark chamber" inLatin) and observed the giantimages that seemed toappear like magic.

The camera obscura andyour pinhole camera are bothbased on a very simple scien-tific principle: Light rays al-ways travel in a straight line.When you look at a tree, youcan see it because light raysstrike the tree and reflecttoward your eye. Of course,the light rays are also beingreflected in every other direc-tion at onr,, too; so no matterwhere you stand, you'll al-ways be able to "catch somerays" and see the tree.

But how do the cameraobscura and the pinhole cam-era "see"? Figure #1 illustratesthat, of all the light rays being

reflected, only one beam oflight, the one that is enteringthe camera pinhole, is impor-tant. The pinhole "captures"that beam in the cameraobscura and lets you viewit alone without any otherbeam of light striking the samespace. If you were to takeaway the pinhole and openthe f, ont of the camera, allkinds of light rays would strikethe rear wall at once, bleach-ing each other out, and youwouldn't be able to see animage at all.

In Figure #2, you can seewhy the image in the cameraappears upside down. Thelight ray from the top of thetree strikes the bottom of therear wall of the camera. Andof course the light ray fromthe bottom of the tree strikesthe top of the rear wall.

FIGURE#2

The camera obscure hasexisted since at least 1038,and it was put to many uses.In the 1200s, scientists realizedthat they could avoid eyedamage by using a cameraobscura, rather than the nakedeye, to observe the sun. In the15005, early astronomers usedthe device to view eclipses,discover sunspots, and evento measure the sun, moon,and stars. And finally, in 1558,a 20-year-old Italian scientistnamed Giovanni Battista dellaPorta puolished a widely readbook called Natural Magic inwhich he described the cam-era obscura. In fact, Battistadella Porta was often credited,in error, with having inventedthe device. However, he didcome up with a new use for it.He realized that the cameraobscura could be use: .yartists, who could trace theimage projected in the camera

and thus have a completelyaccurate and life-like drawingof a landscape, still life,or person.

Soon after, the portablecamera obscura was devel-oped. At first, tents wereused because they could bemoved from place to place.Later, people realized that itwasn't necessary to actuallystand inside the camera tosee the image. A box versionof the camera obscura wasdevebped, using a ground-glass focusing screen, much

like the aluminum-foil screenin your oatmeal-box camera.Through the use of a mirrorplaced inside the box, artistswere able to focus the imageon the box lid. Then theycould lay their paper on topof the glass, and trace away!

10

DARKROOM INSTRUCTIONSFOR PINHOLE CAMERA

This activity is best done atnight, when you can makeyour kitchen or bathroomcompletely dark.

YOU WILL NEED

1 Small package of Dektolpaper developer

Measuring cupLong-handled spoon

for stirring3 Large glass or plastic bowls,

each with at least11/2-quart capacity

Water1 Teaspoon white vinegar1 Small package of

photographic fixativeSink

Tongs

Photographic paper,wristwatch, and safelightfrom camera activity

Paper towels5" by 7" Sheet of glass

or Plexiglas, such as glass

from a picture frameSponge for clean-up

Note: All darkroom workshould be done with waterand chemicals at 68°F. Whenyou are mixing the chemicals,you can judge the water tem-perature by feel. At 68°F,it will feel very cool, almost

cold, but not ice-cold. Thewater should not feel warmat all.

Caution: Photographic chem-icals can stain your clothing,and are irritating to the skin.Avoid touching the developerand fixative. Wash any spillsthoiaughly with clear water.You might also want to protectthe floor from spills by usingnewspapers or a plasticdrorxloth.

11

Mix the Dektol devel-oper according to thedirections on the pack-

age, and pour it into a largeglass bowl. Half fill anotherbowl with water and add1 teaspoon of white vinegarto it. This second bowl iscalled the "stop bath :' In athird bow', mix the photo-graphic fixative according tothe directions on the package.Place these bowls in a kitchen

15 To 30QTES

ADDviNiGATC'-`ATOWATER

30 SECONDSTO 2, MiNurES

LINE OP BOWLS FROM LEFT TO RIGHT

or bathroom. Choose a roomthat can be made completelydark. The bowls should belined up from le to right: fir'developer; then, stop bath;then, fixative. Partially fill thesink with water.

2Make the room com-pletely dark except forthe red safelight. Have

ready your wristwatch, tongs,paper towels, and photo-graphic paper. Open thepackage of paper and takeout just one of the circles thathave been exposed in yourcamera. Ship it into the bowlof developer with the emul-sion side facing up, so youcan see what's happening asit develops. Rock the bowlgent,,,, every 10 seconds. Verysoon you will see a picturestarting to appear. Let the pic-ture develop fully: It shouldtake anywhere from 30 sec-onds to 2 minutes. Don't letthe picture turn black!

3When the picture looksright, use the tongs toremove it from the de-

veloper and drop the pictureinto the stop bath. After 10secon-is, lift the picture out ofthe stop bath and drop it intothe fixative. Rock the fixativebowl gently every once in

1 5, .

91

awhile. Let the picture sit inthe fixative for 5 to 10 minutes.(It is all right to turn the roomlights on after the picture has

been in the fixative for 2 min-utes.) Then put it in a sink ofcool water for 15 to 30minutes to rinse.

Important: Rinse the tongsoff in plain water before youdevelop another picture.You must never get any ofthe fixative or stop bath intothe developer.

4While the first picture isfixing, you can go on todevelop others. Always

work from left to right ...fromdeveloper, to stop bath, tofixative, to the washin3 sink.When all of the pictures arewashed, dry them betweentwo paper towels. You canspeed up the drying by rest-ing them over a warm lightbulb or near a heater.

You will notice that yourpictures look strange. Every-thing that should be dark islight, e J vice versa. This isactually a paper negativejust like the film negatives froma regular camera. Nowyoucan pint a paper positivefrom this paper negative.

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5When the paper nega-tives are dry, go backinto the darkroom. Take

with you a small sheet of glassor Plexiglas. Tape the edges ofthe glass so that you don't cutyourself. In the darkroom,with only the red light on, puta new piece of photographicpaper on the countertop orsome other flat surface. The

shiny, emulsion side of thepaper should be facing up.Put a dry paper negative facedown on top of the photo-graphic paper. Put the sheetof glass on top of both, tohold them tightly together.Make sure that all other photopaper is closed up in itspackage. Na , `lick the roomlight on, then off very quickly,just once. It should be on foronly about 1 second or less.Develop, cix, wash, and dythe new piece of photo-graphic paper just as youdeveloped the paper nega-

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tives. If your exposure wasright, you will have a positivepicture of the scene you pho-tographed earlier in the week!

HINTS FOR SUCCESS

Never turn on the roomlight until you have checkedto be sure that all the photo-graphic paper is put away.

Keep the red flashlight atleast 4 feet away from thephotographic paper if possi-ble. Even this safelight can

"fog" the paper after a while.Keep the paper closed up inits package except when youare actually using ft.

When developing pictures,you may bring the red flash-light very close tl the paperfor a few secona:. .o see howthe developing is coming

NOTES

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158

THROWING IT ALL AWAY 7-8 LA.1HOW MUCH SOLID WASTE DO WE PRODUCE?

1. The average American family of four creates about 150 pands of trash each week. Multiplied by 52weeks, this equals 7800 pounds each year. (To help envision this amount of waste, picture 9 horses (950 lbs.each), 4 1/2 cows (1800 lbs. each), 5 pilot 1hales (1500 lbs. each), or a WW II German fighter plane (7700lbs.) In 1987, Vermont residents, businesses and industries produced an estimated 500,000 tons of solidwaste. With a population of 530,000, this means almost one ton per per.. 3n in the state.

2. In the past 50 years, the amount of waste discarded per person in the U.S. has doubled. Increasedpackaging, increase in number of disposable items, development of industry and production technology, in-crease in personal wealth and purchasing power, and the switch to "planned obsolescence" as a designstrategy are all contributing factors to the increase in personal consumption and disposal.

3. Each day, Americans throw away 400 milliot. pounds of edible food. According to archeologist WilliamRathje of the University of Arizona, this waste consists in large part of spoiled foods never even used. Inaddition, what surpluses do farmers in the US create that are never used and eventually require disposal? Instark contrast to the fcod waste produced in the US -re ' numbers of people who are underfed andundernourished throughout the world. The United Nation. stimates that 460 million people do not receivean adequate amount of thc right kinds of food. The diet of these people is frequently lacking in: -calories(fewer than 2200 calories per person each day is the norm throughout China, India, and much of Africa. UScitizens consume more than 3300 calories per person each day.) -protein (less than 60 grams per day in theabove named places compared to more than 90 grams each day in the U.S.) -needed micronutrients(Malnutrition exists not because we dnn't produce enough food, but rather because of unequal distribution ofwhat is grown. The most affluent third of the world's population eats well over half the food produced.

4. We send 20,000 cars to thejunkyard each day or seven million cars (and 200 million tires) each year.Placed erd to end these cars each year would reach two-thirds of the distance around the earth at the equator.

5. 7.6 million TV's are thrown out each year. Television sets last on average ten to fifteen years. The num-ber of appliances and audio- visual equipment thrown out within only a few years of purchase reflects a fastturnover in technology, the consumer desire for state of the art equipment and new fashion, a planned ob-solescence design strategy by producers, and the fact that it is often less expensive to buy something newthan to repair something old.

6. 90% cf packaging (boxes, bags, and wrappers) is thrown out right away, even though an increasing per-centage of these materials are made of plastic, a substance noted for non-biodegradability and long life.

7. Americans use 50 million tons of paper each year. It takes 17 trees to produce one ton of paper, and10,000 trees to print one edition of the Sunday New York Times. Newspaper is usually discarded within 24hours of being purchased, and only one quarter of the paper produced in the United States is recycled.

8. Vermonters produced about halfa million tons of trash in 1987.

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