I have taught this lesson to 1st graders and 2nd graders before; last time I posted it on my blog, I posted results from 1st grade. The success rate is a little higher with 2nd grade, and the number of students asking for help drops significantly, so I'm leaning toward keeping it as a 2nd grade lesson.
This lesson is in my unit on the principle of art pattern. I began by asking the students to think of animals with spots; then, I asked them to think of animals with lines. Then, I told them that I'm going to show them an animal with both spots and lines! Once the monarch was on the screen, the students noticed the spots around the edge of the wings, and the lines in the center. It looks complicated, but the lines actually make a loop, with lines extending from the loop like sun rays.
The students drew the monarch first, and then added any details that they wanted. I gave them a choice between coloring or painting their details; the only things they were required to paint were the blue sky and the orange butterfly (complementary colors make each other stand out!). Each table got a cup of liquid water colors in orange and blue; then they could ask for up to six other colors.