SAN MATEO, Calif. – On a cool Friday morning in April, the halls of California’s San Mateo High School were full of students chatting, running to class or trying to find their friends.
But one common sight in high schools across the country was and always is absent from the halls of San Mateo: cellphones.
“When you look at the crowd, kids are not buried in their phone,” said Yvonne Shiu, the school’s principal. “They have grown to value being in the moment.”
Students at the public high school about 20 minutes south of San Francisco have been prohibited since 2019 from using their cellphones while in school — from bell to bell. Schools nationwide, including some in Maryland, are now increasingly imposing such bans, but San Mateo was one of the earliest and largest schools in the country to implement a complete ban on cellphones during school hours.
At the start of each day, each of the 1,600 students lock their phone in a magnetically sealed pouch, created by the San Francisco-based company Yondr, that won’t be opened until the school day ends.
The decision to introduce Yondr pouches was the school’s attempt to tackle the increasingly pervasive effects of cellphone and social media overuse on its student body: cyberbullying, loss of sleep, self-esteem issues and endless distractions in class.
Teachers and administrators quickly embraced the program, saying it restored their grasp on students’ attention in class. Some even said if the school were to end the program, they’d leave.
As schools around the country implement similar cellphone bans, San Mateo offers a six-year track record of how a cellphone ban can force young people to focus and, in many cases, feel better.
“If schools can help alleviate some of those expectations and pressures about appearance and performance and embarrassment, and take away some of those elements that a lot of kids really struggle with and are confronted with, that is a benefit to them and to the school community and the school culture,” said Casey Teague, a longtime world history teacher at the school.
A slow start
The decision to implement the Yondr program at San Mateo began with observation and a trial run.
One of its faculty members, Alicia Gorgani, observed a similar cellphone ban at San Lorenzo High School, a smaller school in the area, and brought the idea to San Mateo’s teachers and administrators.
Adam Gelb, San Mateo’s assistant principal at the time, said seeing the cellphone ban in action at San Lorenzo “blew [his] mind.”
“Students were engaged with one another,” he said. “They were interacting. They were playing card games. They were playing out on the yard. They were goofing around. They were in circles, talking to each other.”
Gelb helped bring the program to San Mateo, which tested Yondr pouches in a few classrooms in spring 2019.
Teague, who’s worked at the school for more than 20 years, was one of those first instructors to pilot the program. He said he decided to try out the Yondr pouches in his class after noticing students’ smartphones were constantly bombarding them with notifications.
“By 2018, every kid had a phone. That wasn’t anything new,” Teague said. “But the distracting nature of the phone was becoming more and more obvious.”
Health education teacher Brittany Dybdahl said leading up to the ban, the school was seeing an increase in cyberbullying and drama stemming from online activities.
Embarrassing moments or conflicts among students had the risk of getting captured on video and being immortalized online.
“It basically created way more opportunities for students to be emotionally impacted throughout the school day,” Dybdahl said. “And that would, of course, affect their academics and learning.”
After the pilot program, and many discussions with students and their parents, San Mateo implemented the program schoolwide beginning in the 2019-20 academic year.
Some teachers were apprehensive about the cellphone ban, thinking it would create more work for first-period teachers to check that each student had their phones sealed away.
But those checks quickly became part of the daily routine, said physics teacher Patrick Thrasher.
And after seeing the impact the program had on their students, most faculty members got on board, Thrasher said.
“There was such a pretty clear, drastic difference in the classroom,” he said. “It was just night and day.”
San Mateo’s cellphone ban was not even a year old when the COVID-19 pandemic moved all learning online for a year starting in March 2020. But the school decided to continue the cellphone ban when students returned to the classroom in 2021.
“They do spend enough time already on screens that, you know, seven hours a day here at school [without screen time] is not going to kill them,” Shiu said.
The student reaction
Enforcement of the ban hasn’t been entirely without issues.
San Mateo faculty members said some students — albeit a small percentage — are determined to bypass the Yondr pouches and keep their phones on them. Some put calculators, hard drives or other phone-shaped objects in their Yondr pouches. Others put old, unused “burner phones” in their pouches while keeping their personal phone on them.
But many San Mateo students, like junior Lulu Bertolina, embraced the program. She said the Yondr program was one of the reasons she enrolled at San Mateo.
“Having our phones [in Yondr pouches] made it easier to make friends, because I can’t go off on my phone and not make conversation with people,” she said. “It almost forced it — in a really good way.”
For San Mateo senior Siddharth Gogi, the absence of phones made the school feel more welcoming. He said students aren’t glued to their phones playing video games at lunch or distracted on social media in class.
“Conversations move past surface level when you have that time to talk to one another,” said Gogi, San Mateo’s three-time class president who graduated this spring.
He acknowledged, though, that some students are concerned about not having quick access to their phones in case of an emergency.
In the early 2000s, many schools repealed their cellphone restrictions after the 1999 shooting at Columbine High School in Colorado.
But Shiu said it’s better if students don’t have access to their phones during an emergency. The pouches prevent students and family members from sharing misinformation or flooding 911 with calls overwhelming first responders and the cellphone network.
“In any emergency, we want students to be focused on the adult giving the information,” Shiu said.
The experts
To hear the experts tell it, there’s an overriding good reason for schools to ban cellphones. Cellphone use and social media sites can both have a serious impact on young peoples’ well-being.
Extensive cellphone use during the day has a “direct correlation with a decline in mental health,” said Annette Anderson, the deputy director of the Johns Hopkins University Center for Safe and Healthy Schools.
“We also know that cellphone use late into the evening has a disruptive factor in our young people getting enough sleep and then being attentive enough in the morning,” Anderson said.
Young people are grappling with the reality that the phone in their hand could be doing them harm. A Pew Research Survey released in April found almost half of U.S. teens age 13 to 17 agreed social media sites have a mostly negative impact on kids their age.
San Mateo wellness counselor Helen Citrin said a cellphone ban can provide students a much-needed break from their phones.
For students who are highly anxious or struggle managing their emotions, Citrin said, not having access to a cellphone can help as it prevents them from constantly texting their parents.
“That pouch offers a boundary,” she said.
One recent study echoed this sentiment. Independent research on school cellphone bans is limited, but a 2024 study conducted by Yondr found that students saw a 15% increase in the likelihood they received a passing grade after their school implemented Yondr pouches. The report also found a 44% decrease in behavioral referrals after implementation.
Data from San Mateo paints a mixed picture of the school’s performance since implementation of the cellphone ban. Math and English test scores declined from 2019 through 2024, but both the graduation rate and preparedness for college and careers have inched upward. Meanwhile, the suspension rate increased.
Gelb offered an explanation for the rise: “Everybody was forced to communicate in person, so you had more people talking, and there’s more chance for someone to say the wrong thing or be in the wrong place.”
But, he added, the premeditated incidents and cyberbullying disappeared from the school day.
A growing trend
Although San Mateo might have been early to the cellphone ban movement, it’s among growing company now.
State and local governments and school districts across the country are now considering — or have already passed — policies on cellphone use in school. Yondr boasts that millions of students from all 50 states are now using its pouches.
While there is no statewide ban in Maryland, more than a third of its public schools prohibit cellphone use, Capital News Service reported in October. Several school districts, including Howard and Baltimore counties, have passed a total ban.
About 30% of U.S. schools now have a ban on cellphone use throughout the school day, according to the National Center for Education Statistics.
That percentage is likely to rise. In the nation’s largest state, Democratic Gov. Gavin Newsom (D) signed legislation last year requiring all public and charter schools in California to create a policy to reduce or ban cellphone use during school hours by July 1, 2026, but left each school or school district to decide the specifics of their policy.
And recently, New York joined the more than two dozen other states instituting a complete ban on cellphones during school hours.
Democratic New York Gov. Kathy Hochul (D) said the decision comes as part of the state’s efforts to protect youth mental health.
“Our young people succeed when they’re learning and growing, not clicking and scrolling,” Hochul said in a statement in May.
A model to follow?
San Mateo faculty and staff said the school’s careful implementation of the Yondr program and the conversations it had with families and educators led to its success.
But several San Mateo faculty members said Yondr alone can’t solve youth mental health issues stemming from social media and personal devices.
The second students leave school grounds, they once again have access to their phones and can browse as much as they want. Citrin, the school’s wellness counselor, said many of the students she deals with stay up late into the night doomscrolling, or texting or video chatting with friends.
That being the case, Gelb said schools should also teach students how to develop a healthy relationship with their phone and social media.
The pouches also carry a financial impact on schools.
Each student at San Mateo receives a free Yondr pouch at the beginning of the school year, but each replacement costs $15. In total, Shiu estimated the school spends about $20,000 a year on Yondr pouches.
However, San Mateo teachers and administrators said the program’s benefits outweigh its costs.
“From a school perspective, it keeps kids off of their phone during class time,” Citrin said. “Because the main focus here is education, that’s what the purpose is, and that’s what the use is benefiting.”