The impact of the Washington Physics Education Group on the teaching and learning of introductory physics

The Washington Physics Education Group has had a significant impact on physics instruction through their development of research-based instructional materials. I will focus on the use of their \textit{Tutorials in Introductory Physics} in introductory college-level physics classes. These tutorials are designed to target the very real conceptual difficulties that these students have with classical physics topics. I will describe the design and implementation of these materials and discuss student performance data from a variety of institutions.