This is an interactive Java simulation that illustrates the addition of the primary colors of light: red, blue, and green. It displays two light sources that cast shadows onto a shelf mounted on a wall.  Users control the color of the light sources to see what happens when the primary RGB colors (red, green, blue) are mixed. The resource includes background information on color addition and subtraction.  

This is part of a multimedia teachers' lab on properties of light. The lab is designed to provide teachers with the background knowledge and expertise to set up the same or similar activities for use in the middle school classroom.

Please note that this resource requires Java Applet Plug-in.