Recent studies are looking into the connection between grades K-12 opening and community transmission of COVID-19. Communities surrounding schools without a mask mandate have been found to have higher transmission rates than those that do mandate masks for students and teachers.
Due to the fact that children under 12 are not yet able to get vaccinated and generally show milder symptoms or are asymptomatic, masks in school settings are one of the best ways to prevent wider outbreaks.
Learn more about the findings at https://www.medicalnewstoday.com/articles/covid-19-mask-mandates-in-school-reduced-community-spread