While the development of pedagogical content knowledge (PCK) is considered to be a goal of teacher education, teaching about the concept itself is an unusual practice. In this case study, we explore the outcomes when a teacher educator explicitly introduces student-teachers to ideas about PCK through the use of a CoRes and PaP-eRs conceptualisation. The case study explores how, through this purposeful use of PCK in a pre-service science teacher programme, student-teachers' thinking about their teaching and about their development as science teachers is shaped. (Contains 1 table and 1 note.)