This is a tutorial by the same authors designed as content support for K-12 science teachers on the subject of light reflection.  It is also appropriate for students of introductory physics.

This item is an introductory tutorial on refractive and geometric properties of lenses, accompanied by multiple drawings illustrating various types of both convex and concave lenses.

This item is an interactive Java simulation that examines how the primary subtractive colors (also known as complementary colors) combine to form the primary additives, as well as black.

This item is an interactive Java simulation in which users control a slider to produce concave or convex lenses and explore how the lens shape affects the refraction of light through the surface.

This is an interactive Java tutorial that explores how color perception is affected by changing red/green/blue values and by hue, color saturation, and brightness.

This is an interactive Java simulation that explores how the three primary subtractive colors can be added, along with black, to create four-color prints.