The purpose of the study was to examine how teachers enhance their knowledge of rational numbers focused on modeling problem tasks using multiple representations. The professional development summer institute and the follow-up Lesson Study (Lewis, 2002) throughout the academic year focused on engaging teachers in rational numbers and proportional reasoning problem solving tasks, exploring pedagogical strategies, utilizing mathematics tools and technology, and promoting connections in the elementary and middle school curricula. This research report has two aims: (1) identify ways in which focusing on modeling rational numbers with multiple representations impacted teachers' understanding of rational numbers and proportional reasoning concepts; and (2) examine what strategic competence (NRC, 2001) looks like in teachers as they learn to model rational numbers concepts using multiple models. [For the complete proceedings, see ED584829.]