Demonstrations and Ideas from the Exploratorium AAPT Denver, Spring 2008

Dr. Stephanie Chasteen

CU Boulder, formerly of the Exploratorium Email: Stephanie.chasteen@colorado.edu

MY WEBSITE with lots of science and education http://www.exo.net/~drsteph Copies of this handout (with clickable links!) will be posted at http://www.exo.net/~drsteph/conference.html

BLOG with stuff for teachers http://sciencegeekgirl.wordpress.com/

Teaching tips PODCAST full of Exploratorium activities http://scienceteachingtips.podomatic.com/ Exploratorium TEACHER INSTITUTE http://www.exploratorium.edu/ti TI runs summer workshops for teachers. I can’t recommend their physics institute enough! The HIDDEN Exploratorium WEBSITES: Lots of great activities at my colleagues’ websites, which aren’t published on the main Exploratorium page. http://www.exo.net/~pauld/ http://www.exo.net/~emuller/ http://www.doscience.com/act_archive/

Perception Upside-down “Vanna” face activity: http://www.exploratorium.edu/snacks/vanna.html And the same with the Mona Lisa: http://www.exploratorium.edu/exhibits/mona/mona.html A day’s worth of activities on perception to talk about the nature of human observation and its role in science and pseudoscience: http://www.exo.net/~pauld/summer_institute/summer_day1perception/day1_perception.html Escher staircase of music, or “find the highest note” Also see this link: http://www.exo.net/~pauld/summer_institute/summer_day1perception/find_the_highest_note.html To do and notice

• Play the audio files at http://asa.aip.org/demo27.html or http://www.exploratorium.edu/exhibits/highest_note/ . What do you hear? Are the tones ascending or descending? Find the highest note.

What’s going on?

For most people, the tones appear to ascend or descend forever. This illusion relies on our perception of pitch (ie., frequency). When a note is made of a single frequency, we can accurately judge whether that note is higher or lower than the one before. Each note in this “scale” is made of a set of seven individual notes, played one octave apart. Thus, the first tone, an “A” is made of 55, 110, 220, 880, 1760, and 3520 Hertz. The middle frequency is the loudest, with the volume dropping off to either side of the middle frequency. These individual 7 frequencies change in frequency and volume from note to note in the series. As each individual frequency increases, its volume is changed. Volumewise, they are “sliding in” frequencies from the lower octaves, and “sliding out”

frequencies from the upper octaves. Thus, our ear is fooled into thinking the tone continually increases (or decreases). A great Java visualization here: http://www.netalive.org/tinkering/shepard-effect/

The last straw Do I attract you or repulse you? http://www.exo.net/~emuller/activities/Holding%20Charge.pdf Dry Ice Ice Scream -- Listen to my podcast to find out what’s going on! http://scienceteachingtips.podomatic.com/entry/eg/2007-12-20T19_12_58-08_00 And rattle a coin! http://scienceteachingtips.podomatic.com/entry/2007-08-06T16_48_18-07_00 And carbonate your tongue! http://scienceteachingtips.podomatic.com/entry/2008-03-07T08_23_30-08_00 Fly the Hydra Full description at: http://www.exo.net/~pauld/activities/flying_hydra.html © Paul Doherty, Exploratorium Teacher Institute I used a modified version with a panel of home insulation (instead of the PVC pipe) and cut-up plastic grocery bag (instead of the Chinese wrapping twine). The original hydra activity is great when it works, but has some problems.

Electrophorus Best when combined with the Tape Electrophorus (for testing the sign of the charge). This is a great inquiry activity, at http://www.exo.net/~pauld/activities/tapeelectroscopeshort.html A longer version of this activity : http://www.exo.net/~pauld/summer_institute/summer_day14electrostatic/tape_electroscope.html © Paul Doherty, Exploratorium Teacher Institute Full description of electrophorus activity here: http://isaac.exploratorium.edu/~pauld/summer_institute/summer_day14electrostatic/Electrophorus.html © Paul Doherty, Exploratorium Teacher Institute Fly a piece of tinsel (we dropped it onto the charged pie plate in electrophorus, instead of PVC as in this online writeup) http://isaac.exploratorium.edu/~pauld/activities/Flying_tinsel.html If we have time… Magnets repel grapes! http://isaac.exploratorium.edu/~pauld/activities/magnetism/magnetrepelgrape.html