This year has seen ample debate about the value and fairness of colleges prioritizing diversity among the students they serve. New research suggests one way to consider the question: by looking at how the mix of students in a given course affects their grades.

study published in the journal AERA Open found that students earn better marks in college STEM courses when those classrooms have higher percentages of students who are underrepresented racial minorities or the first in their families to participate in higher education.

That was true for all students — and especially true for the minority and first-generation students themselves.

“Greater levels of representation benefit students from all different backgrounds,” study co-author Nicholas Bowman, a professor of educational policy and leadership studies at the University of Iowa, told EdSurge.

That’s notable, he adds, because discussion about diversity on campus is often reduced to a “zero-sum game,” where one group of students is portrayed as losing and another group of students is depicted as winning.

The study was conducted using administrative data from 20 colleges. Researchers were able to look through grades for every course taken by students of different personal backgrounds.

In STEM courses with higher rates of underrepresented racial minorities, the gap in grades between those students and their peers dropped by 27 percent. In STEM courses with higher rates of first-generation students, the gap in grades dropped by 56 percent.

The findings are notable in STEM disciplines — science, technology, engineering and math — because Black and Hispanic people are not well represented in those fields either as college students or as professionals in the workplace.

So why did diversity affect student grades?

It doesn’t seem to be the case that students performed better because they were selecting into easier courses, Bowman says, nor can easier grading in some classes explain the findings. One hypothesis still standing is that underrepresented racial minority students and first-generation students feel more welcome and a greater sense of belonging when they look around a classroom and see other people like themselves.

Read the full article about diversity in college classrooms by Rebecca Koenig at EdSurge.