New research shows that years after having even one black teacher in elementary school, black students experience major benefits, from being less likely to drop out of high school to being more likely to aspire to college and take college entrance exams .

The recent study comes as there has been increasing attention to diversifying the teaching force, which remains overwhelmingly white, even as the public school student body has become significantly less so.

“In fall 2014, the majority of public school students are now minority, but the teaching workforce is now 80 percent white,” said American University’s Constance Lindsay, one of the research authors. “And we’re actually seeing that the percentage of black teachers has been going down over time.”

Study looks back at Tennessee and North Carolina

To determine how exposure to a black teacher impacts black students, the researchers — including Lindsay, Seth Gershenson of American University, Cassandra Hart of the University of California Davis, and Nicholas Papageorge of Johns Hopkins University — used an extensive data set from the early 2000s in North Carolina.

They examine whether students attended a school and had a class with a black teacher in third, fourth, or fifth grade, and then link that to whether students dropped out of high school and if they said they intended to go to college. To confirm their results, the researchers also compare students to their sibling who did not have any black teachers. The idea is that this ensures that factors outside of school — like poverty or a student’s home life — are not driving the results.

By both methods, the data suggest that black teachers make a big difference. Access to just one cut dropout rates for black students by nearly a third and increased the likelihood of aspiring to college by 3 percentage points. The impacts were much larger for male students, and particularly those in poverty: Access to a black teacher for those students reduced their dropout rate from 18 percent to 12 percent.

Non-black (largely white) students don’t receive a noticeable benefit from having a black teacher, but they weren’t harmed either. Notably, black students did not seem to benefit much more from having more than one black teacher in grades 3–5 as compared to having just one — even a single teacher of the same race seemed to make a big difference.

The study also looks at another data set, this one in Tennessee in the late 1980s. Here, the researchers examined a well-known experiment called Project STAR that randomly placed students with teachers in first, second, and third grade in order to assess the impact of smaller class sizes on student achievement. Because the assignment was random, the data can also be used to see the impact of getting a black teacher versus a white one.

Once again, the effect for black students of having a black teacher is significant: those students were about 4 percentage points less likely to drop out of school and 4 percentage points more likely to take a college entrance exam, such as the SAT.

This suggests that the impacts are real and aren’t specific to North Carolina or grades three through five.

Anna Egalite, a researcher at North Carolina State University who has also found benefits of teacher diversity in her own research, reviewed the study at The 74’s request. She praised the paper — which has not gone through formal peer review — as “interesting” and said she did not “see any obvious biases or glaring issues with the research design.”

Still, she noted that how the researchers counted students in their data without information on whether they graduated could skew their results. The researchers “exclude 14,432 students for whom they are unsure of graduation status. I find these results a little concerning because if those students were truly graduates [it] seems like it would be accurately recorded.”

“If I was reviewing the paper, I'd ask for a lot more info about those kids,” Egalite wrote in an email.

“Her concern is valid,” Lindsay responded, “but we would say that the results for the low-income sample hold up [regardless].”

The North Carolina study looked at 106,370 black students beginning in the third grade.

Fewer suspensions, higher expectations

Why do black teachers seem to make such a big difference for black students? The latest study can’t say definitively, but other research suggests some reasons.

For instance, black teachers seem to view the behavior of black students as less disruptive than other teachers. (Or, alternatively, black students may actually behave differently in the classrooms of same-race teachers.) In turn, other work from Lindsay shows that black students — across elementary, middle, and high school — are less likely to be suspended or expelled by an African-American teacher.

“We find particularly consistent evidence that exposure to same-race teachers lowers office referrals for willful defiance across all grade levels [for black students], suggesting that teacher discretion plays a role in driving our results,” this study notes. A relative scarcity of black teachers may partially explain why black students face exclusionary discipline at much higher rates than other students.

Indeed, in this study, which also focuses on North Carolina, the authors note, “We see that in every [school district] across the state, Whites are more heavily concentrated in the teaching workforce than in the student body. By contrast, every [district] has a higher concentration of Black students than Black teachers.”

There is also evidence that African-American teachers have higher expectations for black students, particularly boys. As one recent study found, “Relative to teachers of the same race and sex as the student, other-race teachers were 12 percentage points less likely to expect black students to complete a four-year college degree.”

Other research has found that black students perform slightly better on standardized tests and are more likely to be referred to gifted and talented programs when paired with black teachers.

Diversity obstacles are many

Meanwhile, it’s not clear if policymakers have caught up to these findings. A 2015 analysis by the Shanker Institute found that the number of black teachers has dropped precipitously in nine major cities.

A study by the Brookings Institution found that at every stage in the process to become a teacher — from those entering training programs to teachers who voluntarily leave the profession — there are gaps that contribute to a lack of diversity.

In hiring, for instance, many districts acknowledge that they simply do not prioritize diversity and teachers of color have lower job satisfaction than white teachers, which might drive higher turnover rates.

The issue extends beyond teachers to include principals who are also largely white. A recent study found that a common exam required for becoming a principal did not predict who was effective on the job, but did disproportionately screen out non-white candidates. Research has directly linked principal diversity to teacher diversity.

Other research has shown that common teacher certification exams also block many prospective teachers of color and are only modestly related to effectiveness as a teacher. At least one state, New York, has tried to address this by eliminating one certification exam that minority test-takers failed at higher rates.

Lindsay believes such tests can exacerbate the problem.

“The [exams that states] are using to ‘raise the bar’ exhibit achievement gaps [for black and white test-takers],” she said. “The issue is that these tests are not [strongly] related to student achievement.”