In this article, we examine collaborative discourse in an informal undergraduate study group in which students focus on their lecture notes. Several decades of educational research have demonstrated that collaborative groups contribute to enhanced learning, and recent work has explored how external representations--such as those that appear in lecture notes--enhance collaboration. However, few of these studies have focused directly on the discourse processes that occur in collaborating groups, or how external representations influence these processes. In this article we use conversation analytic methods to show how the notebooks' external representations affect discourse processes and thus scaffold both individual and group learning. These analyses demonstrate that a close focus on discourse processes can help researchers understand how collaboration using external representations contributes to learning.