Mean girls and callous boys are nothing new. They’ve stalked school hallways and commandeered cafeterias for years. Yet bullies’ arsenal of pain-inflicting tools has never been more relentless; smartphones and social media platforms have erased boundaries of time and space. Anytime, anywhere: So go the slings and arrows of the virtual schoolyard. Fortunately, awareness of bullying’s harmful effects on mental health is widespread. But what about the ways bullying jeopardizes school performance? About this, we’ve known far less.

Until now.

A new longitudinal study from a trio of Arizona State University researchers, published in the Journal of Educational Psychology, reveals a powerful, persistent link between bullying and diminished math achievement. Bullying was tied to lower reading scores, too, but performance rebounded after the early school years. Compared to other students, bullied kids were less engaged in school and felt less competent.

It’s hard to focus on fractions when the lunchroom looms as a place of rejection. What if stress never stops? Researchers found that 24 percent of students experienced “high-chronic” levels of peer victimization; bullying remained “a stable or enduring part of their educational experience throughout formal schooling.”  Think about that: For one in four kids, school was a consistently painful place.

What’s the takeaway for educators? Take findings seriously and act on them. This study’s scope and focus are unprecedented. Researchers tracked the same kids from kindergarten through 12th grade. Families eventually dispersed to 24 states but, remarkably, more than three-fourths of the original 383 students stayed in the study. “We put people in cars or on planes to see these kids,” noted lead author, Gary Ladd, in an American Psychological Association news release announcing findings.

Schools have even greater incentive to stamp out bullying early — and quickly. Students for whom bullying declined dramatically showed evidence of academic “recovery.” Life improved; so did their test scores. This is heartening news. Intervention has power.

How are schools tackling bullying? Todd Pipkin, Head of School at Rocky Mount Prep, a K-12 charter school in Rocky Mount, North Carolina, employs a strategy he describes as “more proactive than reactive.” He focuses on educating parents through “parent universities,” defining bullying clearly for the school community, and creating a safe climate that encourages open dialogue.

Student support is critical; this year Pipkin added two school counselors, for a total of three. And when bullying does occur, Pipkin looks for the teachable moment — “to make sure kids learn from their experience, good or bad.”

Complicating matters today are the tools of technology. A boon to learning, they’re also conduits for cyberbullying. Arizona State University ˚ researchers studied traditional school-based bullying, but cyberbullying is pervasive among tweens and teens. According to 2016 Cyberbullying Research Center data, 34 percent of middle and high school students have been cyberbullied.

In 2009, state lawmakers passed legislation requiring local school boards to adopt policies prohibiting bullying; language covers cyberbullying. Policies must define bullying, outline reporting procedures, set consequences, and more. Such guidance is meaningful, but schools need help from home, too. Parents have a profound effect on a child’s behavior, offline and online.

Pipkin works to keep parents informed about cyberbullying and lets them know supervision is essential. “We want parents to be aware that the technology piece is something you have to really monitor,” he says. A constantly changing landscape of apps and social platforms makes this difficult — “What was new in December is now old,” Pipkin says — but he and school leaders try to stay a step ahead.

It’s important work. And its power for good, to heart and mind, endures.

Kristen Blair is a Chapel Hill-based education writer.