I used this lesson during a science unit on Air and Weather.
We read and discussed the book "It Looked Like Spilt Milk" by Shaw.
We talked about the 4 main types of clouds, and which one was primarily displayed in the book.
First, I brief the students on what our objectives are once we get outside. Then, I take the students outside to the playground. We pick a spot to lay down and look up at the sky. The students start "spotting" different things up in the clouds. "Hey, look, its a bunny rabbit!" or "Wow, did you see that dinosaur?" will be common statements. After 5 minutes (or until they get squirrely) we go back in. A discussion ensues about what we saw in the clouds. I write these on the board or a piece of cloud-shaped butcher paper.
After all the discussion, we are ready to paint. Each student will have an 8" x 11" piece of construction paper and a straw. As I see that they are ready, I come around and put a small amount of white paint on their paper. They will then blow the paint around with their straw, attempting to create one object that they saw in the clouds. Some students will forget to take their mouth off of the straw when inhaling, so a quick note of warning is always helpful!
I love this activity because it incorporates many different learning styles and curricula into it. Not to mention that it is alot of fun! I usually make this into a bulletin board titled "Cumulus Creations" or "It Looked Like...", etc. It is a great excuse to go outside on a sunny day, too!:)