Last year, I did a lesson on Audubon's cardinals, and we talked about how Audubon had studied birds so carefully that he knew just what colors to use in his paintings. Several of the students immediately recognized the bird in the painting as a cardinal, and we talked about how if Audubon had used any other color besides red, no one would know the bird was a cardinal.
This year, I tried polar bears. A white bear is immediately recognized as a polar bear, and an artist needs to know to use the color white if painting a polar bear. There are also some nice images of polar bears in Eric Carle's book Polar Bear, Polar Bear, What Do You Hear? that many students will immediately recognize. I love Eric Carle's art, and I've incorporated his work into lessons for several grades this year. He has a distinctive style, and he is a great gateway into talking about art careers, such as illustrating.
Here are some of my students' polar bears. We drew the bear the first day, and then painted him. The second day, we added the ground (I told them to draw a line that touches all 4 of his feet), and we drew his face with a black crayon. Then we painted the ground, and added little snowflakes in the sky.