Considering the role of mathematics-focused professional development programs in improving teachers' content knowledge and quality of teaching, we provided teachers opportunities for dealing with mathematics problems and positioning themselves as students in a large-scale long-term professional development (PD) project. In this proposal, we aimed to understand the impact of engaging in morning math problems on teachers in terms of their mathematical understanding and teaching practices. Both written work and interviews showed that solving open-ended problems helped teachers better understand the mathematics content and students' challenges as they solve problems; thus, suggested an effective means of PD for teachers. [For complete proceedings, see ED581294.]