Classroom Phone Use Is Higher Than Expected

New app-based data show students use phones far more during class time than many families expect

Topline

Objective app-based tracking suggests U.S. adolescents spend more than an hour per school day on smartphones, with social media accounting for the largest share, even as most schools report having phone-use policies in place.

Study Details

Researchers analyzed passive smartphone data from the Adolescent Brain Cognitive Development Study, one of the largest long-term studies of adolescent development in the U.S. The findings were reported in a research letter published in JAMA by Jason Nagata, MD, and colleagues from University of California San Francisco.

The study arrives as U.S. school districts rapidly revise phone policies, often assuming devices remain stored during class hours.

Methodology

• Passive measurement software tracked real-world app usage on Android smartphones.

• Data included at least two weekdays per participant during school hours.

• Collection windows spanned September 2022 through May 2024, excluding holidays.

• The final sample included 640 adolescents with a mean age of 15 years.

Unlike surveys, this approach reduced recall bias and captured actual phone behavior during school time.

Key Findings

• Adolescents used smartphones an average of 1.16 hours per school day

• Social media apps accounted for about 30 minutes, the largest category

• Video apps averaged nearly 15 minutes

• Gaming apps also averaged about 15 minutes

• Higher school-time phone use was associated with older teens, lower household income, and certain demographic groups

• Problematic social media and mobile phone use correlated with greater in-school phone activity

Implications for Practice

For parents and families:
The findings challenge the assumption that phones remain unused during school hours. Even with policies in place, adolescents appear to access devices frequently, especially for social media. Clear expectations at home and coordination with school guidelines may matter more than blanket assumptions.

For educators and policymakers:
Nearly all U.S. public schools report having smartphone policies, yet objective data suggest enforcement and effectiveness vary. These findings support the need for clearer boundaries, consistent enforcement, and regular reassessment as digital habits evolve.

For clinicians and researchers:
Prior ABCD analyses have linked higher social media use to changes in cognitive performance during adolescence. Objective usage data offer a stronger foundation for studying how school-time digital exposure intersects with learning, attention, and long-term developmental outcomes.