We asked students in two second-semester introductory college physics courses to report on a weekly basis who they worked with on physics outside of class time. One course was a lecture-based course while the second was a studio-based student-centered course implementing the Investigative Science Learning Environment (ISLE). We used social network analysis to visualize and quantify each student's position and engagement in the informal learning community that formed outside of class. Our study analyzed the relationship between students' network positions as they worked together in groups outside the classroom with their performance in the course. We interpreted our results through a participationist viewpoint on learning. Comparisons between the two courses revealed interesting similarities and differences. While the learning communities in these two distinct settings may look very different, our results showed the overarching importance of informal learning communities irrespective of course type.