Data Collection Procedures
All surveys were voluntary and confidential. Trained data collectors administered the electronic self-report survey using tablets. Baseline data were collected before randomization in fall 2016 in the Midwest (872 youth in 55 classes in 10 schools) and fall 2017 in the South (725 youth in 40 classes in 10 schools). Baseline surveys were administered during health classes during the school day. Follow-up surveys were administered at school, pulling students from various classrooms because class schedules had changed. Students who left school after baseline were surveyed at their new schools, online, or by mail.