In this lesson, suggested for grades K-2, students examine the manner in which beavers change their environment to survive by building dams and lodges. Students engage in an engineering design challenge in which they work together as a beaver family to build and test a dam. Finally, they engage in a debate about whether a beaver dam that is causing flooding in a town should be left alone or moved. Before beginning the lesson, we recommend reading Units I and IV, which are included in this book selection. A list of materials, teacher background information, safety notes, standards, assessments, references, and resources are provided. This book selection also includes the Table of Contents, Dedication, About the Author, Acknowledgments, Appendix, and Index.