Rocketflip. UNSAFE, NOT FOR KIDS! Main article: bit.ly amasci.com Can't get liquid nitrogen? Then make your own -80C/110F version by using Dry Ice. Note that this science demonstration involves several major safety hazards, and should only be performed by skilled educators. If used for science fair projects, close parent/teacher supervision is required. But also go see bit.ly SFGATE: "The War On Curiosity" (stamping out hobbyist science in order to keep kids safe.) For lots of suggested low-temp physics demonstrations click on the above link. Or, look on the web for liquid nitrogen demonstrations. Note that dry ice comes from companies listed in your local yellow pages. Some welder supply stores carry it. In Seattle, you can find it in the seafood section of QFC neighborhood grocery, and at some Fred Meyer stores. Ask for dry ice pellets rather than slabs, so you won't have to chop it up yourself. . Lots more stuff at SCIENCE HOBBYIST amasci.com . Note: trolls/spammers blocked immediately, zero tolerance