WATERBURY, Conn. (AP) — It wasn’t until she became a high school senior that Kayla Ireland had another black person as a teacher in Waterbury, a former manufacturing hub where the students are mostly minorities and the educators are generally white.

The imbalance never troubled her much, except for some moments, like when a white teacher led a discussion of police brutality and racial profiling. But the absence of black teachers has been a frequent topic of discussion among Kayla’s classmates at Wilby High School, which has struggled with high numbers of disciplinary issues, including a mass suspension over dress-code violations.

“Sometimes people go through bad days. But because you don’t have that person that looks like you, a person that you can talk to that can relate to it, you don’t really know how to explain it,” said Kayla, 16. “So it feels good to have a teacher that you can go to, and you feel comfortable with, because you’re not going to be deemed the girl in class who doesn’t know anything.”

More than half of the students in American public schools are minorities, but the teaching force is still 80% white, according to statistics from the U.S. Education Department. As mounting research highlights the benefits minority teachers can bestow on students, the gap has received renewed attention, including from Democratic presidential candidates who have endorsed strategies to promote teacher diversity.

The Waterbury school system has taken steps to close the racial gap following complaints from the NAACP. Its limited success so far highlights some of the challenges of addressing the problem, which some see as rooted in teacher training programs and barriers that date back to the 1954 Brown v. Board of Education ruling that led to desegregation.