The purpose of this assessment probe is to elicit students’ ideas about the concept of matter. It is designed to understand how students define matter and whether they recognize that all living, once-living, and nonliving things, materials, or substances are matter. It is best used with students in grades 3–8, but some high school students may benefit to help gain a full understanding of the concept of matter. The probe is provided in English and Spanish. A materials list, teacher notes, standards, assessment, and references are provided. This book selection also includes the Table of Contents, Preface, Acknowledgments, Dedication, About the Authors, Introduction, and Index.