The purpose of this assessment probe is to elicit students’ ideas about complete circuits. It is designed to reveal whether students recognize how just one wire can be used to make a circular pathway of electricity through the battery, bulb, and wire. The probe is best used with grades 3–8, although it can be used with high school students and adults as well because the research shows that even adults have a hard time lighting a bulb with a battery and piece of wire. A materials list, teacher notes, standards, assessment, safety notes, and references are provided. This book selection also includes the Table of Contents, Preface, Acknowledgments, About the Authors, Introduction, and Index.