A friend and colleague at work recommended this book to me. Butterfly Tree, by Sandra Markle with illustrations by Leslie Wu, is a magical and true story about monarch butterfly migration.
The story begins with a little girl seeing "orange" in the sky. Eventually the girl, her mother, and her dog journey through the woods in search of an answer to the mystery. Along the way, they find other orange objects around them but not quite what they are looking for. In the end, they find a magical swarm of monarch butterflies, stopping briefly beforing heading out for the wintertime.
The whole concept and whole story could become a beautiful class dance. Or, you could simply explore the idea of your group of students being butterflies and moving together.
Based on the size of the project and depth of exploration, this book could be used within a wide range of grades - kindergarten through fifth grade.
The author's note at the end of the book provides some more details about monarchs for interested readers.