  Student-to-student interactions are foundational to many active learning
environments, but are most often studied using qualitative methods. Network
analysis tools provide a quantitative complement to this picture, allowing
researchers to describe the social interactions of whole classrooms as systems.
Past results from introductory physics courses have suggested a sharp division
in the formation of social structure between large lecture sections and small
studio classroom environments. Extending those results, this study focuses on
calculus-based introductory physics courses at a large public university with a
heavily commuter and nontraditional student population. Community detection
network methods are used to characterize pre- and post-course collaborative
structure in several sections, and differences are considered between small and
large classes. These results are compared with expectations from earlier
findings, and comment on implications for instruction and further study.
