Very Hungry Caterpillar Mobile. Hang 8" lanterns (1 red, 6 in two shades of green) with different lengths of fishing line. Use pipe cleaners for antennae, and construction paper for eyes and nose. Very cool in a children's library space.
This website has really cool themes to carry throughout your classroom. I found the ocean one to be interesting because one the swimming pool in the picture. I feel like you could use this as a reward for students that had outstanding behavior where they could do either their reading or writing in the swimming pool.