Lill---I can't recommend the Scientists in the Field series strongly enough. It has some outstanding titles by various authors with gorgous photographs. New titles keep coming out. Many deal with wildlife, such as The Tarantula Scientist and The Frog Scientist. There's one on dolphins, one on snakes, etc, etc. If you go to Amazon and type in the series title, you should be able to find them. Or maybe Houghton Mifflin has them listed on their site. Although some of the older students might think they look too young, once they start reading the books, I'll bet they'll be hooked by the information, the photos, and the stories.