In this chapter, we examine student engagement in the science practice of constructing explanations, which is a key practice of science and lies at the core of what the discipline is about. Engaging in explanation construction helps students see how scientific knowledge is constructed. This chapter provides examples of student work from elementary, middle, and high school used to illustrate what constructing explanations can look like in the classroom, as well as how they can increase in complexity across the grades. 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.