The purpose of this lab is for students to apply their understanding of ecosystems and the eating relationships that occur within them. Specifically, students will consider ”Which Member of an Ecosystem Would Affect the Food Web the Most If Removed?” The Teacher Notes provide the connections to standards, references, a timeline, safety notes, information on materials and preparation, and instructions for facilitating the lesson and assessing student outcomes. After the Teacher Notes, you will find a Lab Handout and Checkout Questions. Before beginning the lesson, we recommend reading Chapters 1 and 2, which are included in this book selection. Chapter 1 provides an overview of Argument-Driven Inquiry (ADI) with an explanation of what happens during each of the eight stages of ADI, which are the same for every ADI investigation. Chapter 2 focuses on the lab investigations that were designed using the ADI instructional model. The investigations are not meant to constitute a curriculum or to replace an existing one but rather to change the laboratory component of middle school life science courses. This book selection also includes Table of Contents, Preface, Acknowledgments, About the Authors, Introduction, Appendixes, Image credits, and Index.