The purpose of this assessment probe is to elicit students’ ideas about the conservation of matter. The probe is designed to find out if students conserve matter when salt is dissolved in water. It is best used with students in grades 3–12, with consideration given to demonstrating the probe scenario for students with salt and water. 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.