Imane Belaroussi, from left, Grace Blahourou and Zoélinh Masson on their phones after school in Paris.

PARIS — The eighth-grade girls already know what to expect from France's new smartphone ban in all primary and middle schools because their school voluntarily instituted one last year.

"Annoying," was the assessment of Zoélinh Masson, 12, as her friend Grace Blahourou, 13, agreed.

Still, they said that with no smartphones, students did talk to one another more.

France's education ministry hopes that its smartphone ban, which took effect at the beginning of September and applies to students from first through ninth grades, will get schoolchildren to pay more attention in class and interact more, and several studies suggest such correlations.

Some experts are skeptical that the ban can be enforced, and some teachers question the merits of insulating children from the internet-dominated world they will face outside school. But the French government believes that without minimizing distractions, children will never learn the basics.

"If we want to prepare children in the 21st century, we must give them the tools of modernity: mastery of math, of general culture, the ability to flourish in social relationships, a capacity to discuss with others, to understand and respect others and then very strong digital skills," said Education Minister Jean-Michel Blanquer.

"It's a message we send to society: Do not always be on your phones."

The smartphone ban expands on a current law that applied only to junior high grades and forbade the use of smartphones during class. The new law includes lower grades and will also apply to the entire school grounds, including the schoolyard. The only exception is when smartphones' use is assigned by a teacher.

Around 93 percent of French children ages 12 to 17 have mobile phones, and an estimated 86 percent in that age group have models that support apps, according to French government and research institute data from 2016 and 2017.

Just under two-thirds of middle school and junior high students are signed up on social networks like Instagram and Snapchat and video games like Fortnite.

The problems with smartphone use are well known. Students' insecurity can rise as they constantly worry about keeping up with "likes" and "shares" on social media. Teachers worry about cyberbullying and abusive practical jokes like photographing classmates from under the bathroom door and then posting the images online.

France is rare in legislating a solution. In Denmark, legislators are examining a similar approach, but have said they do not want to put it into law. In Britain, each school makes its own rules. And in New York City, Mayor Bill de Blasio won points three years ago when he lifted a school cellphone ban put in place under his predecessor, Michael Bloomberg.

In New York, as in many American school districts, parents want to be able to check on their children throughout the day. And in school shootings in the United States, students have often used their phones to call 911 and report "active shooter" situations.

In France, where there have been no school shootings, few parents have objected to the ban. The law, a campaign promise of President Emmanuel Macron, flew through the legislature this summer with strong support from parents and many teachers.

About 60 percent of French junior high schools already had similar bans, said Frédérique Rolet, the secretary general of a national teachers union.

Under the new law, students can bring their phones to school but must keep them out of sight in their school bags or lockers. If they are caught using them, the phones can be confiscated for a day.

Yet students say they know how to get around the ban.

Grace, the eighth grader, said that even after her school, Françoise Dolto middle school in Paris, introduced its rule last year, she continued to film her friends for Snapchat and Instagram. She just did it clandestinely.

Both she and her classmate Zoélinh say they take their phones to school even though they are not allowed to use them there.

"In theory I could leave it at home and pick it up after school, but I'd be missing something," Zoélinh said. "I would not feel good at all."

Grace added, half joking, "We'd be depressed."

Both said they felt a void when their phones were not close by. During an interview in a cafe, both girls restrained themselves from doing much texting, but kept touching their phones.

Teachers also doubt whether the ban is enforceable, especially with young teenagers for whom rebellion often trumps any inclination to follow a teacher's instructions.

"I just don't know how the law will be put in place," said Cécile Dhondt, who teaches students who have trouble keeping up in class at College Jean Jaurès middle school in a suburb of Lille, in northern France.

As for taking away phones if students refuse to put them away, she said, "If I confiscated them, my students would not come anymore to class, and that is not the objective."

David Scellier, who teaches French language and literature at a school in a Paris suburb, said that he doubted the law would be an effective "answer to the addiction problem," and that responsibility was being put in the wrong place.

"Who buys the phones for the children?" he said. "Who doesn't give them a framework and set limits on using them? Parents. But everyone blames the school, which is very typical in France: School should be responsible for all the children's problems."

However, he acknowledged that phones were a top concern of the young teachers he trains, who inevitably ask how to deal with smartphone use in class. "Most of them think that they will be more protected with the law," he said. "Let's wait and see. But I doubt it."

For sociologists and scientists in France who study attention spans and the digital culture, removing smartphones from school makes sense even if it does not fully address the difficulty of managing the siren call of social networks.

"It's a culture of presentism," Monique Dagnaud, a researcher at the government-run National Center for Scientific Research, said of social media. "It creates a rapport with the world that is very immediate, very visual, fun."

"The culture of the internet is of immediate pleasure," she added — the inverse of school, which is about delayed gratification.

Smartphone use sets off the production of dopamine — "the same system that is implicated in addictions and drugs," said Jean-Philippe Lachaux, a neuroscientist at the National Institute for Health and Medical Research.

"The problem with the telephone is that it reduces all sensation to what you see and the body disappears," he said. "The world is very much reduced."

That makes the smartphone ban all the more important, he said, so that children "open up to the rest of the world" for at least a few hours a day.