Providing a step-by-step introduction to physics and physical sciences, this book emphasizes discovering rather than memorizing. Starting from their own observations, students construct physical concepts and simple scientific models. A major goal is to help students develop scientific reasoning skills and learn to relate concepts, representations, and models to real world phenomena. "Physics by Inquiry" consists of three volumes. Volume one develops fundamental concepts and basic reasoning skills essential for the physical sciences. The material in volume two provides a foundation for the study of introductory physics. The authors are also working on a third volume, which will introduce additional topics from the standard introductory physics course.