Srinagar, June 6 -- Joanna Houston knew her son spent time on YouTube at school, but the scale simply surprised her.

School records showed that her sixth-grade son in Richmond Hill, Georgia, watched more than 1,500 noneducational YouTube videos on his Chromebook between August and January.

Much of that viewing took place during school hours, turning a device intended for learning into a portal for entertainment.

Houston's discovery shows a growing concern inside American schools. Teachers, parents and administrators increasingly describe classrooms as battlegrounds where lessons compete with notifications, videos and social media feeds designed to capture attention.

Newly disclosed internal documents, reviewed by The New York Times th...