This chapter introduces the book and explores the fundamental shifts implied by engaging students in science and engineering practices. We have many opportunities to make significant and lasting change in the ways we teach science at the K-12 level. This chapter introduces the theme of the book—the contrast between merely knowing about scientific ideas and figuring out how the natural and designed world works by formalizing, sharing, and refining those ideas within a community. We call this figuring out aspect sense-making. When student sense-making is the focus of the classroom goals and purposes, it becomes critical to use science and engineering practices to make sense of the world. A list of materials, teacher background information, standards, assessment, and references are provided. This book selection also includes the Table of Contents, About the Editors, Contributors, Acknowledgments, and Index.