The literature highlights differing views on the efficacy of modelling lessons for teacher professional learning. In this study we draw on dissonance theory to discuss lesson modelling that seeks to transcend 'do as I do' imitation and provoke teachers' attention to intended teaching practices: a necessary pre-cursor for changes to practice. A collective case study investigated the experiences and perceptions of 18 practising primary teachers from four school contexts participating in the process of: collectively observing modelling of mathematics lessons in their classrooms, analysing different parts of those practices with the modeller, and enacting them. It was found that modelling lessons associated with inquiry-oriented approaches for developing students' problem-solving and reasoning in teachers' own classrooms appeared to confront their assumptions about traditional approaches to teaching and learning mathematics. The teachers' surprise at their students' engagement in the challenging learning experiences conflicted with their existing views of teaching and impelled them to reflect on and set goals for improving their practice. Suggestions for pre- and post-lesson protocols for stimulating productive discussions are proposed, along with implications for designing school-based professional learning processes using lesson modelling.