The idea for this project came after the passing of the US Educational Policy No Child Left Behind (NCLB) and a desire to determine what actually influences teachers' decisions in the mathematics classroom. Is it high-stakes policies such as NCLB? Is it what actually happens during the lesson? Do student conversations, solutions, and misconceptions determine what the next step is, or are teachers just turning the page to see what tomorrow's lesson looks like and implementing that? The study was designed to also uncover other possible influences teachers felt pressured by in order to take what happens in a lesson one day and transfer it to the next day's lesson. The focus on 18 teachers, all using inquiry-based mathematics programs in upper elementary schools (Grade 4 in the United States), gives insight into how important professional development is, especially when programs are brought into schools. Supporting teacher development with the program, building ongoing support, and allowing teachers the chance to work together provided a very different experience for students than what happened without these steps in place. Completing this research changed the way I teach