The purpose of this assessment probe is to elicit students’ ideas about the ocean’s salinity. This probe is best used with grades 5–12, and is designed to uncover students’ ideas about the role of landforms and rivers in carrying salt into the ocean. Understanding why the sea is salty begins with knowing how water cycles among the ocean’s physical states: liquid, vapor, and ice. 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.