Schools instituting strict bans on cell phones have found their students’ test stores go up by about 6 percentage points.

Researchers from the University of Texas and Louisiana State University examined schools—many of which had enacted strong rules to ban or strictly limit cell phone use—in four British cities. When they reviewed the schools’ exam scores for a period of time, they found that schools that banned phones saw their test scores go up, sometimes dramatically.

“We found the impact of banning phones for these students equivalent to an additional hour a week in school or to increasing the school year by five days,” said the study’s authors. Another bonus: Scientists saw the biggest improvements in students who typically underachieved or were disadvantaged in some way. (Time)