PLAINFIELD — Another New Jersey school has opted to lock up cell phones during classes under a partnership with tech company Yondr.

Under the program, students keep their device on them but each phone gets put into a locking pouch for the school day. Phones are turned to silent, vibrate or off before they are secured, so as not to disrupt the phone-free space, according to company spokeswoman Kelly Taylor.

Federal law makes it illegal for venues to intentionally jam cell phone signals.

"We understand that cell phones have great utility, but cell phone use has increasingly become a source of distraction, antisocial behavior, and conflict both at home and at school," Maxon Middle School Principal Kevin Stansbury said in an open letter on the Plainfield school's website.

Stansbury said this first week of the program has been a bit of a "learning curve" for students and staff while the middle schoolers have adopted the new policy even better than he had anticipated.

He said seeing some kids playing the card game, Uno, at lunch was a refreshing change, as kids now have more space to communicate face to face, instead of through screens.

Yondr is used in hundreds of schools across the region, including at least three more in New Jersey — Collegiate Academy in Newark, Burlington County Alternative School in Mount Laurel and the Moriah School in Englewood, Taylor said.

Each specially designed soft cell phone case requires an unlocking base to open.

Stansbury said after he had seen a report on the company, he researched it and reached out to their office and within days they sent prototypes for the school to try.

Some of the oldest students on a school leadership team tested the cell-phone pouches before the full rollout among the school of 755 students in sixth through eighth grades.

Stansbury said the negative impact of social media had been an issue, with students using Instagram and Snapchat during the school day. Cyberbullying is also a problem, he said.

In his letter on the school website, Stansbury also cited a survey from Common Sense Media that found that a majority of parents and about half of teens admitted they were very attached to their mobile devices.

Yondr also has been used in courts and at special events like weddings.

Families can reach their children by calling the main office.

Stansbury said each teacher has an unlocking base, so in the event of a true school emergency, kids' cell phones would be easily accessible.

EDITOR'S NOTE: An earlier version of this story should have said that the pouches do not block cell signals.

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