The National Audubon creates an excellent introduction to the Rocks and Minerals, Birds, Wildflowers, and Insects for children aged 8-18. Each guide is appropriately sized to fit in a field vest pocket.
My favorite animal is the mountain lion. it is a silent hunter and is very stealthy. It has signs to tell if there is one around. One of the signs are that the front and back paws are in pairs of two. The front paw is 3 1/4 inches and the back is 3 inches. It is interesting how the front is bigger than the back.
I just finish this book. It's great. If not trying to learn a mountain of info on one animal only this is for you. Each page is jammed packed with beautiful photos and great passages about the animal.