We examine the distinction between teaching and teachers as it relates to instructional improvement. Drawing from work outside of education on improvement systems and from analyzing the Japanese system of lesson study, we contend that a focus on teaching can shape a coordinated system for improvement whereas a focus on teachers, common in the United States, leads to elements that are uncoordinated and often work against the continuous, steady improvement of classroom teaching. We propose that the concept of systems for improvement and its instantiation in Japanese K-8 education offer opportunities to reexamine U.S. efforts to improve teaching and shift these efforts toward a more promising direction.