The purpose of this assessment probe is to elicit students’ ideas about electromagnets. It is designed to reveal what variables students think affect the strength of an electromagnet. This probe is best used with middle and high school students. If materials are available, consider modeling the probe scenario. 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.