In Spring 2010, the Oregon State University physics department instituted a SCALE-UP (Student-Centered Active Learning Environment for Undergraduate Programs) style studio classroom in the introductory, calculus-based physics series. In our initial implementation, comprised of two hours lecture, two hours of studio, and two hours lab work, the studio session was lead by a faculty member and either 2 GTAs or 1 GTA and 1 LA. We plan to move to a model where senior GTAs can lead studio sections after co-teaching with the faculty member. It is critical that we know how to prepare and support the instructional team in facilitating student learning in this setting. We examine GTA and LA pedagogical beliefs through reflective journaling, interviews, and personal experience of the authors. In particular, we examine how these beliefs changed over their first quarter of instruction, as well as the resources used to adapt to the new classroom environment.