Nearly every American public school has a phone policy. Some schools use locked pouches. Others ban devices entirely. A few allow phones during breaks but not class time. The rules vary, but the intent is universal: keep students focused on learning.

New research published in JAMA shows those policies aren’t working. American teenagers spend an average of 70 minutes per day on smartphones during school hours—and that’s just the measurable time on social media, videos, and games.

What the data shows

Researchers at UC San Francisco analysed smartphone use among 640 adolescents aged 13 to 18, tracking their Android devices between September 2022 and May 2024. Unlike previous studies that relied on teens self-reporting their screen time, this research used passive monitoring software that captured actual usage.

The findings: teens averaged 1 hour and 10 minutes daily on phones during school hours. Social media apps—Instagram, TikTok, and Snapchat—accounted for nearly 30 minutes. YouTube and gaming apps added another 15 minutes each.

Lead researcher Dr. Jason Nagata, associate professor of pediatrics at UC San Francisco, noted that “this moves the conversation beyond anecdotes and self-reports to real-world behavior. Teens are not always accurate reporters of their own screen time. Objective smartphone data gives us a clearer picture of actual use.”

The study found that older teens (ages 16 to 18) and students from lower-income households showed higher phone use during school hours compared to their peers.

The enforcement gap

Here’s the disconnect: 99.7% of American public school principals report having policies governing student phone use. At least 32 states and the District of Columbia require school districts to ban or restrict smartphones. Yet teens are still spending more than an hour daily on devices during school.

Dr. Dimitri Christakis, co-author and director of the Center for Child Health, Behavior and Development at Seattle Children’s Hospital, said the effect of state laws “remains to be seen.” He noted that policies “to date have been very poorly enforced, if at all.”

The research didn’t evaluate which specific policies work or how different enforcement approaches compare. What it reveals is the gap between stated rules and actual student behavior.

Why this matters

Seventy minutes might not sound dramatic until you consider what it represents. That’s more than an hour every school day when students should be engaging with lessons, participating in class discussions, or focusing on assignments—time instead spent scrolling social media or watching videos.

The study notes that this 70 minutes happens “literally during the school day when children and adolescents should be in classes.” It’s not break time or lunch periods. It’s during instructional hours.

This data confirms what teachers have been reporting: widespread phone use continues regardless of rules. Some students check devices between classes. Others scroll under desks during lessons. Many find moments throughout the day when monitoring isn’t consistent.

The passive tracking also captured usage that students themselves might not accurately report. Previous research relying on self-reporting may have underestimated actual use, particularly for behavior students know violates school rules.

What teachers already know

If you’re an educator, this research likely confirms what you see every day. Students glancing at phones under desks. The subtle glow of screens during lessons. The mental absence even when devices aren’t visible.

The 70-minute average means that in a typical six-hour school day, students are spending nearly 20% of instructional time on devices. That’s more than one full class period daily spent on social media and games instead of learning.

This data gives you language for conversations with administrators about enforcement. When school leadership claims a policy is working, you can reference objective tracking showing students still average over an hour daily on phones. The gap between stated policy and classroom reality isn’t anecdotal—it’s measurable.

The study also clarifies what students are actually doing on devices: primarily Instagram, TikTok, and Snapchat. Not educational apps or research. Not emergency communication with parents. Platforms specifically designed to capture and hold attention during the time when you’re trying to teach.

What parents should know

The JAMA study provides objective data rather than speculation about what might be happening. It shows the scale of phone use during school hours and which apps dominate that time: primarily social media platforms designed to maximise engagement.

“These apps are designed to be addictive,” researchers noted. The platforms students access during school hours—Instagram, TikTok, Snapchat, YouTube—all use algorithmic feeds and notifications specifically engineered to capture attention.

For parents wondering whether their child’s school phone policy is actually working, this research suggests the answer is probably not. Even in schools with explicit bans, enforcement remains inconsistent enough that students average over an hour daily on devices.

A separate survey cited in the research found that 71.3% of American adults support banning smartphones in schools. The data suggests that support hasn’t translated into effective implementation.

What comes next

The researchers note that understanding actual usage patterns is essential for developing effective policies. Schools implementing restrictions need data about what’s really happening, not assumptions about compliance.

Some schools have moved beyond honour systems to physical interventions—locked pouches that prevent access, collection systems at building entry, or consequences for visible phone use. The effectiveness of these approaches compared to policy-only restrictions wasn’t measured in this study.

What the research establishes is baseline behavior against which future policy changes can be measured. If a school implements stricter enforcement, comparing subsequent data to this 70-minute average would show whether the new approach actually reduces use.

For parents, the takeaway is simpler: school phone policies probably aren’t doing what you think they’re doing. The gap between rules and reality is wide enough that students are spending significant instructional time on devices designed to capture their attention.

That’s worth discussing with your children—and possibly with their school.

SOURCES:

• JAMA: “Smartphone Use During School Hours by US Youth in the Adolescent Brain Cognitive Development Study”
• UW Medicine Newsroom: “Study: Teens use cellphones for an hour a day at school”
• CNN: “Kids are spending a lot of their school days on their phones”
• Education Week: “How Much Time Do Teens Spend on Their Phones During School?”