Do small classes in higher education reduce performance gaps in STEM?

Performance gaps in science are well documented, and an examination of underlying mechanisms that lead to underperformance and attrition of women and underrepresented minorities (URM) may offer highly targeted means to promote such students. Determining factors that influence academic performance may provide a basis for improved pedagogy and policy development at the university level. We examined the impact of class size on students in 17 biology courses at four universities. Although the female students underperformed on high-stakes exams compared with the men as class size increased, the women received higher scores than the men on nonexam assessments. The URM students underperformed across grade measures compared with the majority students regardless of class size, suggesting that other characteristics of the education environment affect learning. Student enrollment is expected to increase precipitously in the next decade, underscoring the need to prioritize individual student potential rather than yield to budget constraints when considering equitable pedagogy and caps on classroom sizes.