The whole point of this activity is to let my second grade students mess around with primary colors to make secondary colors. I also throw in a little mini-lesson on using the brush appropriately and encourage students to not only use equal amounts of two primary colors, but also to use UNequal amounts to create different shades.
Rather than have all students use all three colors, I set up each of three large tables with two primary colors of tempera paint in small containers: one table with red and yellow, one table with blue and yellow, and one table with blue and red. Students choose which table at which to paint. Each student gets a small paper plate on which to mix paint, and a medium-sized round watercolor brush.
My directions are pretty basic: I suggest that they use the paper plates to mix colors, and make sure they understand that they don't need to paint a picture of something but that they can just play around with lines, shapes, and patterns. I also ask that their finished painting have at least three different colors. This confuses some students, but I try not to say more than that.
The first time I did this activity I figured that, at the very least, students would use both primary colors and one mixed color. I found that some students used only mixed colors and figured out on their own that adding more of one of the primary colors would alter the color. Others needed a little creative questioning: "How much red did you use?" "What would happen if you used more yellow?" and the like.
For some students, color mixing is not new. For others, and a surprising number of them, they are surprised to get green or orange or purple. I find that kind of sad. Some students like to paint a picture of something, others are happy to play with lines, shapes, or patterns. I was surprised and curious to find some students spending an inordinate amount of time painting the paper plate itself and avoiding the paper altogether.
Discussion is pretty basic, relating to which primary colors create which secondary colors. It is during the discussion that I introduce the words primary and secondary, and show a color wheel.