Well before political leaders were taking action against cellphones in the classroom, the superintendent of schools in Schoharie, N.Y., a rural district about 40 miles west of Albany, was well along on his crusade against Big Tech’s commandeering of the adolescent mind. By the beginning of the school year in 2022, David Blanchard, who had been appointed as superintendent seven years earlier, had implemented a bell-to-bell policy. This meant that students could not use phones (or smart watches or earbuds) at any point during the school day — not during lunch or study halls or periods of transition from one class to another.

The effort certainly seemed extreme. This was before Jonathan Haidt’s book “The Anxious Generation” spurred consensus about the destructive impact phones were having on teenage mental health, before the former surgeon general’s call for warning labels on social media platforms. Mr. Blanchard was troubled by all the disconnection he was seeing. His experiment yielded benefits right away.

“We found a transformative environment,” he told me recently. “We expected kids to be in tears, breaking down. Immediately we saw them talking to each other, engaged in conversation in the lunchroom.”

One unanticipated outcome was that students flooded counselors’ offices looking for help on how to resolve conflicts that were now happening in person. Previously, if they found themselves in some sort of fight with someone online, they would have called or texted a parent for advice on how to deal with it, Mr. Blanchard told me. “Now students were realizing that their friends were right there in front of them and not the people on social, a few towns away, that they had never met.” Enrollment in elective classes also went up when the option to scroll your way through a 40-minute free period was eliminated.

The success in Schoharie has been a showpiece in Gov. Kathy Hochul’s recent campaign to ban cellphones in schools across New York. At least eight other states, including Florida and Louisiana, have instituted restrictions of varying kinds. In September, Gov. Gavin Newsom signed the Phone-Free School Act requiring every school district in California to devise a policy limiting the use of smartphones by July 2026. This week a suggested cellphone ban was the subject of a public hearing in the Texas State Legislature, where a bill was introduced with bipartisan support a few months ago by a young member of the House who lamented that she had been “born into these devices.”

Governor Hochul’s proposal follows the Schoharie bell-to-bell approach. In a rare instance of agreement between labor and government, it is supported by the United Federation of Teachers, the union representing New York City schoolteachers. As Michael Mulgrew, the president of the U.F.T., put it, “It is simple, and everyone knows what the expectation is.”

Still, the proposal’s all-constraining formulation has not made it an obvious or easy sell. Introduced in January as part of the state’s current budget negotiations, it is opposed by some groups like the state’s School Boards Association. These groups favor an alternate strategy coming out of the statehouse that endorses the notion that local jurisdictions ought to have say in how policy limiting phone use is devised.

Studies comparing students with and without cellphones in classrooms generally show better academic performance among those without. The advantage of keeping devices out of students’ hands for the entire day is that it both reduces the time teachers have to waste policing phone use and also minimizes the possibility that whatever erupts on Snapchat during lunchtime will kill any chance of paying attention to the “Moby-Dick” discussion in the afternoon. In Schoharie, students put their smartphones in a pouch with a magnetic lock — the kind used in stores to prevent theft — which cannot be opened until a school attendant releases them at the end of the day.

In recent years, parents around the country have demanded more and more control over what their children are reading and doing in school. The constituents most opposed to all-day phone bans are the mothers and fathers who seem to be addicted to constant filial contact. Governor Hochul has spoken to aggrieved first-grade teachers who told her that they are overseeing classrooms full of children wearing smart watches. “Mommy and Daddy were checking in all day long saying, ‘I miss you and can’t wait to see you,’” the governor told me. “That’s a parental need,” she said, “not a student need.” The continuation of these patterns, she worried, was bound to keep children from emerging as fully functioning adults.

It is the sadly all too reasonable fear of many parents that something catastrophic could happen at school without their being able to reach their children. It is a fantasy that communication would save them. Throughout the rollout of the proposal, the governor’s office has had law enforcement come in and speak with school groups to explain how misguided a notion that is. In an emergency, phones distract children from remaining focused on whomever has been entrusted to keep them safe; calls and texts create added panic.

Should the governor’s proposal pass, it would take effect in September. Parents in Schoharie were quite resistant to the ban at first, Mr. Blanchard told me. But they came around when they realized that with the addiction broken, it became much easier to manage their children’s digital lives at home — and much more gratifying to see them engage with the world without staring at their hands.