The purpose of this assessment probe is to elicit students’ ideas about magnetic fields. It is designed to find out how students would represent a magnetic field using magnetic field lines. The probe is best used with middle and high school students after they have had some familiarity with magnetic fields and magnetic field diagrams or observations of fields using iron filings sprinkled around a magnet. It should be revisited after students have had instructional experiences to learn about magnetic fields. 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.