This book is about responsive teaching in science and mathematics. Before we explore nuances in the nature of responsive teaching, challenge common assumptions in the literature, and connect responsive teaching to other, relevant constructs-as do many of the chapters in this book-we first offer a rough sketch of what it is and what it looks like in practice. Our goal in doing so is not to make distinct analytical points or to add to the literature by challenging notions of responsive teaching; it is to give examples of responsive teaching and to show how each one instantiates this kind of instruction-to illustrate the phenomenon, so to speak, and to establish shared meaning for responsive teaching before we explore it together in the rest of the book.