California’s San Mateo High School, which commenced the 2019-20 school year on August 14, has initiated a new and exceptionally unpopular policy—one they don’t intend to repeal any time soon.

Beginning this year, cell phones are entirely banned during the school day.

“We could walk into a variety of classrooms, and kids would be on their cell phones anywhere from 5 seconds, checking a text, to 30 to 45 minutes at a time,” said Adam Gelb, the school’s assistant principal to NBC in an interview. He called cell phones addictive, and said that they interfere with the process between students, teachers, and each other, which harms the learning process.

There’s some research to support that. Calvin Newport, a professor of computer science at Georgetown University, maintains that students perform worse if they have uncontrolled internet access in the classroom.

“It’s a good general function of our schools to be a place where our students get trained to keeping their concentration on one thing at a time,” added Newport.

A 2018 study from Rutgers University confirms this with numbers: students who had access to cell phones or laptops during class time scored as much as 5% lower on exams over the material than students without electronics on hand.

At San Mateo, cell phones are still allowed to be brought to school, and remain in each student’s possession, but school policy is to secure each device in a locking bag at the beginning of the school day. The bags, which are provided free to students, can only be unlocked by a magnetic device the teachers all carry, and will only be unlocked at the end of the day.

The policy does have its detractors. Psychologists say that teenagers use their phones to alleviate anxiety, and unable to check in even on their breaks and lunch will build up worries. And there are learning professionals who believe that this policy will teach students that distractions can only be managed by being eliminated, which may hamper their work ethics as adults.

The policy is new, and currently being observed. It still may be modified in the future.