We are doing the same approach here. I strongly suggest using the Native American folk tales and legends before using fictitious books written by non-natives. They are rich with tradition, history and environmental awareness. You can find a lot of them by searching online. Another great thing to do is to try your hands at making some arts and crafts as well as housing models. Not all Native Americans lived in teepees and the homes are such a wonderful and connected way to learn about the environmental impact on lifestyles around North America. Children really seem to grasp this concept.