For a fun, hands-on activity on the subject of color mixing, I divide a can of vanilla frosting into three containers and then mix each with one of the three primary colors (red, blue, yellow). Then I give each child a full graham cracker. On one end I place a large dab of each of the three colors, to make three piles. On the other end of the cracker the students combine colors using their fingers. I ask them to combine yellow with blue, yellow with red, and blue with red. This gives them the new colors of green, orange and purple. After the oohs and ahs, I let them eat their crackers and frosting. Then we fill in a color wheel together. Two books I find particularly enjoyable for this subject are: 'Little Blue and Little Yellow' by Leo Lionni and 'Mouse Paint' by Ellen Stoll Walsh.