I saw a great demonstration the other day in class about the color of light. It is similar to a lesson plan found at: http://science.hq.nasa.gov/kids/imagers/teachersite/UL1.htm
The Color of Light
To begin, my classmates drew two venn diagrams. One had the colors of paint (red, yellow, and blue) and the other had the colors of light (red, green, and blue). We guessed which colors created which new colors (orange, green, purple and yellow, cyan, and magenta, respectively).
Next, they turned on three light bulbs (a red, green, and blue one). All other sources of light was covered and a large white projection screen was against one wall. One classmate put a meter stick in the way of the light and in front of the screen. It was amazing to see the meter stick separated the light into yellow, cyan, and magenta. Then the light bulbs were turned off one at a time. When the red light bulb was turned off, the background of the screen was cyan, while green and blue were separated by the meter stick. Similar results occurred when the green and blue light bulbs were turned off.
It was just amazing!! Try it at home if you don’t believe it :o)