Over the past dozen years the WebPhysics and Open Source Physics (OSP) projects have produced some of the most widely used computer-based curricular materials for the teaching of introductory and advanced physics courses.  These materials are based on Java applets called Physlets and on new OSP programs and authoring tools. This session describes how we use these materials in the Davidson curriculum to motivate and engage students in computational physics modeling.  In addition to learning to program, students are required to write and communicate, to develop their graphical design skills, and to apply mathematical reasoning to complex problems.  We will demonstrate how physics can be taught by modeling, and how this approach helps to deepen the understanding of the underlying physical principles while supporting computational thinking.