The purpose of this assessment probe is to elicit students’ ideas about types of circuits—series and parallel. It is designed to reveal students’ thinking about the effect of circuit configuration on bulb brightness. The probe is best used with middle and high school students. It can be extended by adding an additional bulb so there are three bulbs in each circuit. If materials are available, consider showing each of the circuits without lighting the bulbs. It’s important students know that the same type of battery is used in both circuits. 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.