How Researchers Measured Teen Smartphone Use During School

To get a real picture of what students were actually doing, researchers skipped the surveys. Instead, participants uploaded daily screenshots from their iPhone’s built-in screen time feature for 14 consecutive days. Those screenshots captured how many minutes each student spent on their phone during each hour of the day, giving researchers a window into school hours specifically, defined as 8 a.m. to 3 p.m.

All 79 students came from the same school district in the Southeastern United States, split into two groups: 51 high schoolers aged 15 to 18, and 28 middle schoolers aged 11 to 14. Because researchers knew the district’s schedule, they could isolate school hours from after-school and weekend use, though they could not separate actual class time from informal periods like lunch or passing periods. Thousands of hourly data points were collected across the study period, producing one of the most detailed real-world records of in-school phone behavior to date.

Across the full sample, phone activity was recorded during every hour of the school day without exception, from 8 a.m. straight through the final bell. On average, screen time climbed steadily from about 16 minutes at 8 a.m. to more than 22 minutes by 2 p.m. One student logged more than five hours of phone use during school across the study period.

High schoolers used their phones considerably more than middle schoolers, averaging about 23 minutes of screen time per hour compared to roughly 12 minutes for younger students. For the middle school group, researchers also tracked which apps were getting the attention. Social media platforms, including TikTok, Instagram, and Snapchat, combined with entertainment apps like YouTube, accounted for nearly 70 percent of total school-hours screen time. Students in that group averaged about 40 minutes on social media during the school day and nearly 14 minutes on entertainment, both active throughout every hour.

High schoolers were also tracked for how often they physically picked up their phones, a count that included any device interaction, not just social media use. Students reached for their devices an average of 64 times per school day, roughly nine or ten times per hour.

Researchers then tested that older group’s mental focus using a go/no-go task, a standard exercise in which participants must press a button in response to one image but hold back when they see another. It measures a person’s ability to override an automatic impulse, a basic building block of self-regulation. Note that the cognitive testing was conducted only in the older cohort, so it isn’t known whether the same patterns would hold for younger students. Still, among those tested, students who picked up their phones more often during school performed worse, and the pattern held even after accounting for total screen time. How long students stared at their phones had no measurable connection to performance on its own. The checking habit was what mattered.

Several states have moved toward banning phones in schools, and these findings add important context to those ongoing debates. The authors note that bans alone may not be sufficient. Compulsive checking, reaching for a phone out of reflex rather than intention, is the behavior most closely tied to attention and self-control outcomes. Addressing it likely requires digital literacy programs alongside policy, helping students recognize what constant interruption does to their own ability to concentrate.

Younger students may be the more receptive audience. Middle schoolers in the study pulled back their phone use on school days compared to non-school days, a pattern their older peers did not show. Building better phone habits before high school, rather than trying to dismantle entrenched ones during it, may be where schools and parents can have the most impact.

Students in this study used their phones throughout the school day, and researchers detected activity during every hour. As more districts debate what to do about devices in classrooms, the most telling number from this research may not be the screen time total, but the 64 daily pickups.