This simple experiment demonstrates the space air molecules take up as they are heated and cooled.
Start with a pan of hot water and a pan of ice cold water. Then take an empty two liter bottle and put a balloon over the top. Place the bottle in the hot water and watch the balloon inflate. Then move the bottle to the cold water and watch it deflate. The science behind this experiment is that as air molecules get hot , they move around more and occupy more space, thus inflating the balloon. When the ballon was moved to the ice water, the molecules cooled off, moved closer together and occupied less space. So cool! Thanks to our cousin Joshua for helping us out with this experiment.