Texas Education Agency
Texas Gateway: Electrifying Energy
This tutorial reviews over electrical energy.
PBS
Pbs Kids: Design Squad Game: Fidgit Power
Help Fidgitville by designing wind turbines that make electricity and keep the air and water clean.
Integrated Publishing
Integrated Publishing: Levers
A quite lengthy chapter on the simple machine the lever. Includes uses, classes, mechanical advantage, formulae, etc. A full discussion, with good illustrations.