Cold doesn't exist by itself. Cold just means there's less heat energy around. Take a cold room for example. It's cold because it doesn't contain a lot of heat energy. Some of its heat energy escaped! To make ice cream, you must remove heat energy from the cream. Heat energy moves from places with more heat energy to places with less. So, heat energy flows from the cream to the ice, cooling the cream and melting the ice. Once the cream loses enough heat energy, it freezes and becomes a solid. Shake things up with this "Fetch!" activity, and turn a liquid into a solid. If you succeed, you'll have a tasty treat to enjoy at the end! Yummm.