In this activity, learners investigate color vision as well as plan and conduct their own experiments. In "CLASS EXPERIMENT," learners discover that afterimages occur because of properties of cells in the retina and because of the way nerve pathways carry color information to the brain. They learn basic facts about photoreceptors, nerve connections, and opponent colors. In "TRY YOUR OWN EXPERIMENT," learners design experiments, investigating, for example, how skillful people are at distinguishing gradations of color and how color helps us discern objects in a scene. This lesson plan includes background information and guides for educators and learners.