A putt-putt boat is a very simple steam engine that is made from household materials such as an aluminum can and plastic straws. With 1 intake straw and 1 outtake straw and a boiler full of water, a candle is lit under the boiler. The candle heats the water and increases the pressure inside the boiler, pushing water out the outtake straw, and propelling the boat forward. After making the boiler, a hull is made from a plastic folder and the boiler is glued in. To observe how different shaped hulls determine the speed of the putt-putt boat, students also carved boat hulls out of balsa wood using apple peelers.