Exploring the affordances and limitations of PCK: a three-year case study of model-based teaching through a conventional and expansive lens

Pedagogical content knowledge (PCK) has long served as a framework for understanding how science teachers can transform disciplinary content into forms that are accessible and meaningful for students. However, as science education increasingly emphasises equitable and knowledge-generative practices, questions remain regarding PCK’s capacity to capture the complexity of these instructional shifts. This longitudinal single instrumental case study examines the affordances and limitations of PCK mapping for understanding a high school biology teacher’s enactment of model-based teaching over three years. Drawing on video-recorded lessons, ancillary materials, and interviews, we analysed instructional sequences using two lenses: conventional modelling and expansive modelling. Findings indicate that PCK maps effectively captured shifts in conventional modelling practices, particularly those involving increased coordination of conceptual, epistemic, and representational dimensions of modelling. However, PCK maps were less sensitive to shifts toward equitable modelling practices characteristic of expansive modelling. In several instances, the strongest PCK maps aligned with multidimensional modelling rather than broader expansive modelling practices. This suggests that while PCK mapping is useful for examining instructional coherence and professional growth, it may obscure equity-oriented dimensions of model-based teaching. We argue for analytic pluralism, combining PCK with complementary frameworks to more fully capture the complexity of contemporary science teaching.