This is a video I found about additive and subtractive color. It's really cool. CMYK color is similar to yellow, blue and red color like you use in art, just a different selection of colors.

This website have cool tools that let you play with adding color.

You can play with adding cyan, magenta, yellow and black (the k is for key) in this picture. For more fun, do the advanced activity.

This page lets you play with color shadows.

Play with color filters for LASERS and light bulbs.