Rubber bands are different than many other materials because their molecules are actually very long chains, kind of like a tangled pile of spaghetti. These long chains are called polymers, which can behave in surprising ways when you heat or cool them. In this activity you will change the temperature of a rubber band using hot water and ice water, The rubber band actually expands when it gets colder! This seems counterintuitive because most materials expand when they are heated and contract when they get cold. This occurs because of the unusual polymer structure of rubber. When the long chains get hotter and vibrate, they actually shorten, causing the material to contract. When the chains cool down, they relax and stretch out, causing the material to expand.
