Physics

General Physics Sites
The Exploratorium Physics 4 Kids Phet - Free Online Interactive Simulations from the University of Colorado at Boulder.

Forces
[|Engineering Interact] Animation that shows gravity, friction, compression, stretching and magnetic forces in a fun way, at 'Parkworld', an amusement park. Fossweb - Force and Motion from the Full Option Science System

Simple machines
Inventors Toolbox - The elements of machines (phots and descriptions) including sketches from Leonardo Da Vinci. Gadget Anatomy - a short quiz about the simple machines that make up more complex machines. "If Simple machines were not around...?" - a worksheet for students Simple Machines game from the Museum of Science and Industry

Energy
Energy Quest - Science projects about energy.

Electrical Circuits
Flash animation to create circuits

Light
Optical Illusions Change Blindness - an optical phenomena that causes the observer to miss changes in two images when flashed on a screen.