Very Cool StuffAir, Water, and Cryogenics
Classroom Program (4th grade and up): Hands-On
PREVIEW (5 min)
Have plenty of balloons blown up.
Place "To Be Frozen" objects along edge of stage.
Pour up Igloo cooler with LN2 (big cold vapor show).
Place ONE single balloon into Igloo and put lid on.

Who are we? What do we do?
What are the connections among air, water, and cryogenics?
Hotdog hand (safety talk)
Boiling water versus boiling nitrogen (more safety talk)
What makes a good scientist? (house cat)

AIR (10 min)
What is air? (It is not nothing!)
Balloon in vacuum chamber
Marshmallow man in vacuum chamber
Making liquid air….balloon in LN2

WATER (10 min)
What is water? (The most unique substance in the known universe!)
Boiling water in vacuum chamber….feel the water; drink the water
Temperature measurements using thermocouple: room air, ice water, .....

How cold is cold? Measure the temperature of LN2 (-321 F or 77 K)
Temperature has a limit going down (absolute zero) but not going up.
What is cryogenics?
a) Energy part
Hold up candle: energy is about hot and cold.
Film boiling and/or quench the metal (What is energy?)
Pressure relief valve contraption
Film cannister pop-off and ping-pong ball spinner
b) Temperature part
What are cold temperatures used for?
Making artificial ice, freezing foods, shipping medicines, MRI scans, building computers, telescopes, night vision, store energy, superconducting power cables, etc.
c) Materials part
Rubber tube, tygon tube, racquet ball, tennis ball, etc.
Smashing pennies (old and new)
Now for Freezing crazy stuff: banana, flower, bungee cord, flip flop, etc.

Pour remaining (small amount) of LN2 into warm pan.
Two things to remember: -321 deg F and cryogenics = energy
Super-frozen marshmallows for the teachers (and students if small class)

1. Quench of a "hot" object: a) pouring LN2 into dog dish, b) dunking steel nut into LN2 [LAWS of THERMO...all 4!].
2. How cold is cold? Boiling water (373 K), ice water (273 K), ice cube into LN2 (77 K) and set out on table, helium in MRI (4K).
3. Making liquid air: a) inflate balloon and put into cooler of LN2, b) pour LN2 into coke can and suspend at an angle.
4. Nitrogen is inert: a) put flame above dog dish, b) cook cup of LN2 in microwave oven.
5. Change in physical properties of materials at low temperatures: a) tennis ball or raquet ball quenched in LN2, b) rubber hose or inner tube, c) rose or other flower, d) tygon tube or bungee cord made into a coil spring.
6. Brittleness of some materials at low temperatures (remember the Titanic): quench pennies in LN2 and hit with hammer (pennies before 1982 are 95% copper while pennies after 1982 are 99% zinc with copper plating).
7. Film boiling (part of Safety Talk): water on hot griddle, LN2 on pool of water, any hot object into LN2 [initially, vapor pocket; effectiveness of convection versus conduction heat transfer].
8. Energy potential: a) balloon quench and re-inflation, 700X expansion, b) pressure relief contraption, c) film canister pop-off.

LN2 (10-liter dewars) and safety gear
Dog Dish
Igloo Cooler (clean)
Balloons, long balloons, and air pump
Tongs, pliers, and hammer
Heat Gun
Lighter stick and candle
Pennies: old and new
Hotdog hand and pack of hotdogs
See-through plastic vacuum can and vacuum pump
Hot plate and pyrex pan
Pressure relief valve contraption
Fuji film capsules and holder
Thermocouple readout and thermocouple
Cup of warm water
Cup of ice water
Ice cubes
Stuff to freeze: marshmallows, banana, other foods, tygon tube, rubber tube, flowers, etc.
Insulation materials: shuttle foam, aerogel granules, glass bubbles, MLI, etc.

CHECKLIST OF STUFF TO BRING (Air travel location):
Safety gear (gloves and eye wear)
Small Dog Dish
Tongs and pliers
Matches and candle
Pennies: old and new
Fuji film capsules and holder
Thermocouple readout and two thermocouples
Stuff to freeze: marshmallows, banana, other foods, tygon tube, rubber tube, flowers, etc.
Insulation materials: shuttle foam, aerogel granules, glass bubbles, MLI, etc.
Insulation Test Fixture (Dixie Cup Type)
Obtain locally: LN2 (5-liter dewar), Igloo Cooler or foam box, Cups of warm water, ice water, ice cubes