Institutions of higher education are seeking to support more active learning among faculty, and that support includes the creation of active learning spaces to support more student-centered course activities. However, incremental development of these learning spaces leads to a sorting of students between active and passive learning environments. This study collected repeat-measure data from undergraduate students enrolled in a two-semester course sequence to evaluate factors affecting student enrollment decisions and student attitudes toward learning. We integrated this combination of research tools using a QuantCrit analytic framework, which revealed student attitudes and decision-making processes that were generally stable over the study period for individuals, but very different when examining student enrollment groups over time. Limited access to active learning classrooms forced students to self-sort based on either their social networks or their attitudes toward learning. That, in turn, may create a marginalizing force that pushes out some students--most often women--from undergraduate programs.