Smartphone Use Among Adolescents During School Hours: High-Intensity Objective Observations Across Different Instructional Contexts

Adolescent smartphone use in school, and how it shapes learning and development, has gained substantial attention. Yet, objective data on digital behavior during school hours is limited. This study uses high-intensity smartphone observations from 139 adolescents (Mage = 15.52; 47.2% female) over six months to examine patterns across face-to-face, online, and blended instructional contexts. Use duration was significantly longer during online instruction (Median = 133.50 mins) and shorter during face-to-face (Median = 70.74 mins), compared to non-school days (Median = 92.38 mins). Use was often off-task, with social media or video players most used. Two case studies highlight idiosyncrasies in use. Findings highlight the contextual, personalized nature of smartphone use during school hours, and inform education policies and interventions.