This paper reports on a professional development (PD) which aimed to support secondary teachers in incorporating argumentation and proof-oriented tasks in their classrooms. The teachers interacted with researcher-developed models of proving tasks in a variety of ways, including modifying the tasks to their classrooms contexts, implementing the tasks, sharing and reflecting on the experiences. In the process of modifying proof-oriented tasks by teachers some of the original researcher-intended goals were lost, while other unexpected affordances emerged. This raises important questions regarding modes of teacher-researcher collaborations around proof-oriented classroom interventions, and their potential effectiveness.
