I just found this great comparison lesson from Life in First Grade. I love to use venn diagrams when comparing things with students. I think sometimes with all of the thinking maps out there, we forget about using venn diagrams. My students always seemed to do a much better job making comparisons when we used a Venn than they did when we used a double bubble map. Check out Leslie's post Last Week in Pictures for more information and ideas for using The Country Mouse and the City Mouse.