For nearly a decade we have taught the history and philosophy of science as part of courses aimed at the professional development of physics teachers. The focus of the history of science instruction is on the stages in the development of the concepts and theories of physics. For this instruction, we designed activities to help the teachers organize their understanding of this historical development. The activities include scientific modeling using archaic theories. We conducted surveys to gauge the impact on the (...) teachers of including the conceptual history of physics in the professional development courses. The teachers report greater confidence in their knowledge of the history of physics, that they reflect on this history for their teaching, and that they use of the history of physics for their classroom instruction. In this paper, we provide examples of our activities, the rationale for their design, and discuss the outcomes for the teachers of the instruction. (shrink)