Class Size, Students' Evaluations, and Instructional Effectiveness

Students’ evaluations of instructional effectiveness were collected in two different university settings (N = 1,341 classes), while faculty self-evaluations of their own teaching were also collected in one of these settings (N = 190 classes). The magnitude of the class-size effect depended upon the specific component of the evaluations being considered. The effect was large for Quality of Group Interaction, but was small for 10 other components including Overall Course and Overall Instructor ratings. The form of the effect was clearly nonlinear; small and large classes were generally rated more favorably. The effect tended to be weak, and much of the observed relationship could be explained in terms of other demographic variables such as percentage of freshman and sophomore students. Finally, relationships between class size and different components of faculty self-evaluations were generally similar to those found with students’ evaluations. These findings, particularly that very large classes tended to be rated as favorably as small classes, challenge the widely held speculation that effectiveness of instruction necessarily suffers in classes with large enrollments.