How Hydropower Plants Work
HowStuffWorks tells you how hydropower plants work. They are one of the most widely used energy sources worldwide, used to power 24% of the world. There is also a diagram of a plant and a list of the basic components of a hydropower plant. They have lots of parts!
The Energy Story - Chapter 12
Chapter 12 of the energy story discusses hydro power. They give a great history lesson on when waterwheels were used to grind corn, farther back than the year 1086 AD. Nowadays we use that moving water to create electricity (which we probably use to grind our corn!).