A balloon is dropped in boiling water, and another balloon is cooled with liquid nitrogen to demonstrate the effect of temperature on volume of gas in a balloon.
A 4 liter beaker on a hot plate, with a liter of water boiling within. A prepared balloon, filled with air and tied so that it just fits in the beaker, is dropped into the beaker. The balloon expands to seal the beaker and is forced up by the vapor pressure, ending up on top of the beaker, too large to fit inside.
A foam ice bucket will hold a helium ballon that is large enough to seal around the inside of the bucket...
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