Schools watch their students. Nearly every responsibility that schools shoulder includes an element of surveillance--from ensuring that preschoolers do not wander off, to keeping third graders on task, to stopping bullying and sexting. These responsibilities are not new, but schools' increased ability to monitor students continuously is. Despite introducing more than 400 bills on student data privacy since 2014, states have yet to address privacy protections for school surveillance or its inequitable effects. This report examines this important, emerging issue, identifying the benefits and potential problems posed by school surveillance. The authors suggest six principles to guide state policymakers toward effective, balanced policies.