Just-in-Time Teaching (JiTT) is a pedagogical approach that requires students to answer questions related to an upcoming class a few hours beforehand, using an online course management system. While the phrase 'Just in time' may evoke shades of slap-dash work and cut corners, JiTT pedagogy is just the opposite. It helps students to view learning as a process that takes time, introspection, and persistence. Students who experience JiTT come to class better prepared, and report that it helps to focus and organize their out-of-class studying. Their responses to JiTT questions make gaps in their learning visible to the teacher prior to class, enabling him or her to address learning gaps while the material is still fresh in students' minds - hence the label 'just in time'. JiTT questions differ from traditional homework problems in being designed, not only to build cognitive skills, but also to help students confront misconceptions, make connections to previous knowledge, and develop metacognitive thinking practices. Students consequently spend more time on course concepts and ideas, but also read their textbooks in ways that result in more effective and deeper learning. Starting the class with students' work also dramatically changes the classroom-learning environment, creating greater student engagement. This book demonstrates that JiTT has broad appeal across the academy. Part I provides a broad overview of JiTT, introducing the pedagogy and exploring various dimensions of its use without regard to discipline. Part II of the book demonstrates JiTT's remarkable cross-disciplinary impact with examples of applications in physics, biology, the geosciences, economics, history, and the humanities.