Historically, teachers implemented mathematics reform recommendations by infusing new activities into the curriculum. However, mathematics instruction continues to be teacher centred, challenging professional developers to find new ways to encourage teachers' growth. This study used activity-reflective cycles (Tzur & Simon, 1999) to examine different coaching approaches to support teachers' use of rich mathematical tasks and questions to promote students' mathematical thinking. We suggest a new coaching approach characterised as "evoking teachers' pedagogical curiosity" to advance teachers' professional growth. (Contains 2 tables and 1 figure.)