The first "unit" we did this year was based around the book The Kissing Hand by Audrey Penn. It features a bunch of woodland animals and their homes. So one of the things we did was make a tree house for Chester (a raccoon) to live in. As with many things, it was a much more fun process than end product, mostly because it was so small inside you couldn't really fit 2 kids in to play inside! But it was fun to make (good fine motor/hand strengthening to cut the branches) and smelled great as the branches dried out.