The purpose of this assessment probe is to elicit students’ ideas about layers of sedimentary rock. The probe is designed to find out how students think about the age of rock layers. It is best used with grades 6–12, and students should be familiar with sedimentary rocks before using. Students should also know that the probe is about layers of sedimentary rock, not rock in general. A materials list, teacher background information, references, assessment, and outcomes are provided. This book selection includes the Table of Contents, Foreword, Preface, Acknowledgments, About the Authors, Introduction, and Index.