The Responsive Math Teaching (RMT) project’s 3-year model for professional development introduces teachers to a new instructional model through a full year of monthly Math Circles, where they experience problem solving and productive struggle from the student perspective while working through challenging open-ended tasks, engaging in mathematical discussions, and reflecting on the process. This paper examines teachers’ views of what they learned from this experience and how it affected both their instructional practices and their visions of mathematics teaching and learning. This study focused on a group of 34 participants from a network of urban elementary schools who attended monthly after school sessions over the course of one academic year. We highlight key findings in relation to (1) what teachers learned from engaging in solving challenging math tasks as learners, (2) key elements of their developing visions of mathematics teaching and learning, (3) changes they reported to their math instruction. The evidence suggests that by the end of the introductory year, teachers were primed and ready to learn new skills and practices to help bring their developing visions into practice in the classroom.