This paper examines the effect of the architectural layout of two classrooms (one flexible and one less-flexible) on Teaching Assistants' (TAs) movement and interactions with students. Four TAs from a first-year undergraduate introductory course were chosen for the two studies. In study 1, the TAs taught the same lesson twice to two groups of students on the same day but in different classrooms, thereby controlling for content differences. Study 2 investigated the impacts that flexible and non-flexible spaces have on the same cohort of students, as the TAs continued to teach the same students but the students switched classrooms for the second half of the course, thereby controlling for differences in student participants. From the video analyses, there was a clear difference in how the TAs moved in the classroom and the interactions they had with students. Both TAs and students reported in surveys that there was a difference in their movement in the respective rooms that had an impact on their teaching and learning quality. This finding starts the conversation on how space can affect TAs, in order for TAs to consider how their movement is affected by classroom configurations, and how this change in movement can affect teaching strategies and impact their students' learning