Promoting positive attitudes about science among teachers has important implications for teachers' classroom practice and for their relationship to science as a discipline. In this paper, we report positive shifts in teachers' attitudes about science, as measured by the Colorado Learning Attitudes about Science (CLASS) survey, over the course of their participation in a professional development course that emphasized the flexible use of energy representations to understand real world scenarios. Our work contributes to the larger effort to make the case that professional development matters for teacher learning and attitudes.