The purpose of this assessment probe is to elicit students’ ideas about extensive properties. It is designed to determine whether students recognize that weight (or mass) and volume are extensive properties of the three familiar states of matter. The probe is best used with students in grades 3–8, and is designed to uncover conceptual understanding and purposely does not use the technical vocabulary of mass and volume. 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.