I read the story, "If the Dinosaurs Came Back" to my 1st graders. We talked about how the illustrator used contrast between the colored dinosaurs and the black and white background. Students drew an environment with Sharpie on day 1 - no pencils!
On day 2, students cut dinosaurs out of construction paper and glued them onto the background. I gave students photocopied shapes to build their dinosaur, but I encouraged them to design their own.