  Research suggests that interacting with more peers about physics course
material is correlated with higher student performance. Some studies, however,
have demonstrated that different topics of peer interactions may correlate with
their performance in different ways, or possibly not at all. In this study, we
probe both the peers with whom students interact about their physics course and
the particular aspects of the course material about which they interacted in
six different introductory physics courses: four lecture courses and two lab
courses. Drawing on methods in social network analysis, we replicate prior work
demonstrating that, on average, students who interact with more peers in their
physics courses have higher final course grades. Expanding on this result, we
find that students discuss a wide range of aspects of course material with
their peers: concepts, small-group work, assessments, lecture, and homework. We
observe that in the lecture courses, interacting with peers about concepts is
most strongly correlated with final course grade, with smaller correlations
also arising for small-group work and homework. In the lab courses, on the
other hand, small-group work is the only interaction topic that significantly
correlates with final course grade. We use these findings to discuss how course
structures (e.g., grading schemes and weekly course schedules) may shape
student interactions and add nuance to prior work by identifying how specific
types of student interactions are associated (or not) with performance.
