Background: A school district in Northern Ohio implemented a COVID-19 surveillance program from January 4 to May 21, 2021, as in-person school and extracurricular activities resumed. Methods: Among 560 staff members and >6300 students, random weekly testing was performed on 563 students and weekly for 204 students participating in extracurricular activities, and 553 staff. Results: Cases of COVID-19 were identified among 26 staff members and 23 students. Most of those infected were participating in extracurricular activities (14/23) and in the age range of 14-18. Percent positivity was low (range 0.2-2.4%) throughout the school surveillance program despite significant changes in positivity rate (2.8-19.8%). Conclusion: This demonstrates that in a setting employing basic yet consistent mitigation strategies, there is low transmission among young children and adolescents as they return to in-person classes and activities. Maintaining layered prevention strategies implemented and sustained with fidelity can substantially limit transmission within schools.