In this paper we report on a Learning Study (LS) focused on the teaching and learning of the economic concept of price. Cycles of action research informed by the variation theory of learning were undertaken by a group of secondary school teachers facilitated by the authors over a period of nine weeks. As researchers and facilitators, we were interested to see what effect this form of professional development would have on the teachers' pedagogical content knowledge. We are able to report that for a majority of the teachers, the experience of the study provided them with an opportunity to gain insights into the ways their students became able to experience price in a more powerful way as a result of the patterns of variation incorporated in the research lesson designs, and that this in turn led the teachers to reflect on the ways in which they had experienced teaching before the LS and on the possibility of changing their approach to teaching in the future. In other words, participation in LS does have the potential develop teachers' pedagogical content knowledge. In this paper, we report the context of the study, review the concepts involved, report the process and discuss the findings.