If you're interested, check out Catch Foliage Sites on the Internet and the Follow Fall Colors by Telephone page. And, for more advanced information about synthesis there are a ton of sites. Check out the ASU Photosynthesis Center . From Arizona State University, the site includes links to many other sites. Written at about a fourth grade level, the book tells the story of a boy who decides to solve the mystery of photosynthesis for a school science project.
Students learn all about photosynthesis from the book.
Collect a variety of leaves and challenge students to use a tree guide from the library to identify the kind of tree from which each leaf comes. To protect the leaves, you might laminate them. You might even join a listserv and post a message asking teachers in other regions to join in a leaf exchange. You're bound to meet up with a teacher willing to share native leaves. Collect samples of colorful leaves and place the leaves between sheets of wax paper.