This PowerPoint presentation is what I use to introduce color to my high school Studio Art class, but this could be used for 5th grade and middle school art classes as well.
This is a brief introduction to where color comes from and how to make primary, secondary and tertiary (intermediate) colors. I typically use the aid of a light shining through a prism, color paddles and a light refractor that I got from the Science department to show the students the color spectrum and where color comes from. (They LOVE this!) This presentation is a great assistance and visual aid when having my students complete a Tertiary Color Wheel.