From the Physics Classroom, "an online, free to use physics website developed primarily for beginning physics students and their teachers," comes this series of lessons about vectors. These lessons are designed for use as an interactive, multimedia textbook, providing teachers with a useful instructional tool and students with a useful study aid. Divided into three main lessons (Vectors: Fundamentals and Operations, Projectile Motion, and Forces in Two Dimensions), this textbook includes a variety of accessible explanations, real-world examples, helpful diagrams, animations, and practice problems. One especially useful feature of this resource is that the solutions to problem sets are hidden from users until they select a link, allowing students to test their skills and understanding. In addition, embedded hyperlinks let students quickly look up vocabulary terms or concepts as they read or work through a problem.