Handout includes more demonstrations and tips.
To demonstrate that the primary colors of light are red, blue, and green. Put the red, green, and blue lights into the light bulb sockets then put the sockets into the power strip. Turn the strip on and use your hands to make shadows on the white background. This causes interference in the light which causes all the colors in the rainbow to be seen. If the students are still in doubt, replace the green bulb with the yellow.