Table 1. Description of cohorts used in this study.

Level	n unique courses	n unique sections	n matched students (% of total registered)	mean number of students per class
100	2	13	1431 (47%)	235
200	4	9	1773 (70%)	281
300	5	5	413 (47%)	175
400	4	4	48 (56%)	21
Total	17	31	3728