School phone bans get devices out of students’ hands, but led to no improvement in discipline or test scores, a large-scale study found.

Thousands of US schools require students to put phones in locked pouches; the researchers observed the impact over three years, compared to schools that did not introduce the policy.

Attendance rate, self-reported attention in class, and test scores all showed little or zero change; disciplinary incidents and suspensions spiked briefly, and wellbeing dipped at first before recovering.

The bans were unpopular with students but more popular with parents and teachers. The study’s author told The New York Times that the results were “encouraging” and warned against abandoning the bans because scores did not rise immediately.