Your child will love playing with his food to make a working potato cannon. This explosive experiment demonstrates the basic principles of Boyle's Law, which states, "Under constant temperature, the volume of gas is inversely proportional to the total amount of pressure applied." In the case of the popping potato, the air in the pipe is the gas, lodged between two potato plugs. By shoving a broomstick into the pipe of the potato cannon, one plug pushes towards the other reducing the volume of gas, while increasing pressure. The pressure in the potato cannon is what sends the potato plug flying into the yard!