My students seem to really love this project. They seem to love creating artwork about disasters. These are collages. The tornado is made of cotton batting and I show them how to form it into a tornado. Houses, cars, trees, flowers etc. are made completely out of paper. I ask the students to have at least one house, one tree, and one vehicle in their finished picture. The rest is up to them. In the last 15 minutes of class, I let them use oil pastels to add final details.
I found this lesson on one of my favorite websites, http://techyteacher.net/artlessons/fourth/tornado.html