National Geographic has some great resources for education, including the Nat Geo Education site, Nat Geo Animal Facts site, Ancient Sea Monsters, and the Traveler's Guide to the Planets. They also have a great interactive site on Wind Power.
The Wind Power Interactive site goes through how a wind turbine works, how the energy is converted to electricity and more. It's a great site to use with Environmental classes, Physics classes, or pre-engineering classes.
It's one of many interactive sites Nat Geo has.