The intensity of the light beams can be adjusted by blocking part of the lens. Students should realize that mixing colored pigments and mixing colored beams gives different results. Have students predict the results of mixing red and blue beams, and mixing blue and green beams as above. Ask what will happen when all three colors are mixed. From the results draw the color wheel on the board.
Students are familiar with mixing crayons.
Ask how to make green when no green crayon is available. Show mixing of combinations of magenta, cyan and yellow filters on the overhead. From end flap of a food carton find the color of the inks used. Use a magnifying glass to observe that the picture is formed from the overlapping of colored dots. This next part has to do with the formation of shadows formed by blocking the light from overlapping colored light beams.