Chief Justice Roberts asked why diversity matters in a physics class. Here’s an answer.

The big question at the heart of the affirmative action case before the Supreme Court, Fisher v. Texas, is whether the university needs to consider race in its admissions process in order to create an environment diverse enough to benefit all students.

Oral arguments on Wednesday focused a lot on diversity not just at the university level but in individual classrooms. And that led to a question from Chief Justice John Roberts: Why does diversity matter in a science class?

According to the transcript (slightly edited to cut out repetition):

CHIEF JUSTICE ROBERTS: What unique perspective does a minority student bring to a physics class?

MR. GARRE: Your Honor —

CHIEF JUSTICE ROBERTS: You're counting those among the classes in which there are no minority students. And I'm just wondering what the benefits of diversity are in that situation?

The Supreme Court's rulings on affirmative action say it's constitutional to consider race in college admissions in order to achieve the educational benefits of diversity for all students — not to benefit students of color specifically.

Many of the arguments about those broad benefits, meanwhile, are about discussion-based classes in the social sciences and humanities, where students' backgrounds could influence their perspective and contributions. Math and science classes don't always work that way. So a generous interpretation of Roberts's question is whether the presence of minority students still makes a difference to everyone, since that's the test an affirmative action program has to meet.

Diversity in the science classroom is good for everyone

Sometimes there are direct educational benefits: A study of students in medical school found that white students studying at more diverse colleges said they felt more prepared than their peers at less diverse schools to meet the needs of patients of different races.

But there are also broader reasons why having more students of color in the classroom is important. Minority students are particularly underrepresented in science, technology, engineering, and math (STEM) fields. This underrepresentation can create a vicious cycle: Students don't have mentors and role models of their race, they don't feel they belong in their classroom or department, and they don't have a support system.

They're also more likely to change majors. Thirty-six percent of black students who entered college as STEM majors changed their mind before graduation, a higher rate than any other racial group, according to a 2013 study from the National Center for Educational Statistics.

More diverse classrooms and better support systems can help stop that attrition, the National Academy of Sciences, a group of leading researchers, has argued. They also ensure that the math and science talent of students of color doesn't go to waste.