For all the lessons available on colour theory, here is a simple one that demonstrates the effect that colour has on the retina. It is as much a science experiment as it is an emotional art experience, but rest assured, it is an art lesson.
After the actual experience, students are then asked to research and respond to works by Modern artists who work in colour field paintings. Have them apply the experience to those works, and explain why and how it happens.
The actual experience is non-grade specific, but the research component is higher grade level.