Originally called "Putt Putt Steam Boats" in the 1920's, these reproduction toys can be used to teach many scientific principles. Using a small flame from a candle or a few drops of cooking oil, the 4 inch long boats will chug along for hours. It is great for demonstrating the transformation of heat energy to mechanical energy. More advanced students can be given the problem of explaining how it works. Fascinating to watch in a circular pan of water.
