Here's a lesson/activity I did the other day with a second grade class in which I had the luxury of plenty of time. Including the introduction, it probably took a couple of hours for those who worked the longest.
We started out by brainstorming a list of things that have or are circles. The brainstorming session, which took maybe ten minutes, was followed by a read-aloud of the book The Dot by Peter Reynolds. Then we looked at photos of two Kandinsky paintings which are composed almost entirely with dots: Farbstudie and Several Circles. I asked students to comment on these two paintings; they noticed that he had used many colors, that some dots or circles were inside others, and that some were overlapped.
While giving directions, I introduced the term mixed-media, which in this case included any combination of crayons, markers, colored pencils, and collage, and also the terms representational and non-representational. They were given very simple directions: to use mixed-media, and to see what they could do with a dot, either representationally or non-representationally. Then they went to work and I observed.
Some students started large, while others started very small. Some partitioned their papers, and some started with borders. Once they were started and getting involved with their compositions, I invited the students to get up and walk around to take a look at what other people were doing with their dots. I reminded them that getting ideas is ok, but copying is not. Watching the students work on these was a real treat. They loved the activity and everyone was completely concentrating on their own work, including the wiggliest of students. One of the best moments was watching one little boy with a marker in each hand, drawing circles with both hands simultaneously.
This lesson would be great anytime kids need a creative break. It was all successful. Here's what the white board looked like after the introduction: