My 5th grade students have been learning about the principle of art pattern. We looked at several photographs of hot air balloons, and noticed the patterns on them, as well as the shape of them. The students drew their own balloons (and any other details they wanted in their art) with crayons on watercolor paper. Then, they painted the sky with liquid watercolors, and used a balled up paper towel to dab away clouds, while the watercolors were still wet. It's a fun watercolor technique with great results, that only works on watercolor paper! Other papers are usually so thin that the paint soaks all the way through.