Hydroelectricity is very much in the news and I have been developing some "hands on" projects to illustrate how dams create hydro power. Hydro power was so important to economic development in Maine but also came at a price for waterways. This project engages students in the creation of a water wheel/water turbine toy that can also generate energy. They can learn the history of these two forms of energy production --one that powered machinery and another that generated electricity.
An additional function can illustrate optical science. The property of the "persistence of vision" was used in the 19th century Victorian Toy, the thaumatrope, an early form of animation. Students can create animations to appear when the side wheels spin.