The purpose of this assessment probe is to elicit students’ ideas about chemical change. The probe is designed to find out whether students recognize that the same kinds and numbers of atoms are present before and after a chemical reaction. It is best used with students in grades 6–12, once they can use the idea of atoms to support their explanation. The probe can be extended by having students draw a model or provide a symbolic representation, such as a chemical equation, to support their thinking. 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.