The guiding question of this investigation is, How does adding more batteries or bulbs to a closed circuit affect the brightness of a single bulb within that circuit? In this lesson, the goal is to figure out how the addition of more batteries and bulbs to a closed circuit affects the brightness of a bulb in that circuit. There are many ways to create a closed circuit and to accomplish this goal, students will need to think about how to create a closed circuit with more than one battery or bulb in it. The Teacher Notes provide connections to the standards, a timeline, safety notes, information on materials and preparation, and step-by-step instructions for facilitating the lesson and assessing student outcomes. After the Teacher Notes, you will find classroom-ready reproducible pages in the form of an Investigation Handout and Checkout Questions. Before you begin the lesson, we recommend reading Chapters 1 and 2, which are 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 investigations and how to use them, not to replace an existing science curriculum, but rather to function as a tool that teachers can use to integrate three-dimensional instruction into their existing curriculum. Also included in the book selection are the Table of Contents, Preface, Acknowledgments, About the Authors, Introduction, and Index.