The purpose of this assessment probe is to elicit students’ ideas about mass. It is designed to find out if students understand the difference between mass and other properties. The probe is best used with students in grades 6–12, and can be used with students in grades 3–5, if they have been introduced to mass. 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.