A: HEPA filtration units are one good option.
See below for some helpful guidance put together by Johns Hopkins Bloomberg School of Public Health and Johns Hopkins Center for Health Security:
“Parents are facing hard decisions right now about in-person schooling. They may not know, for instance, that HEPA filtration units help reduce COVID-19 spread in the classroom or that the Johns Hopkins Center for Health Security has released detailed recommendations for improving air in schools.
Ask your child’s school today what they have done to improve air quality and lower risk. If your child’s school is not able to meet updated COVID-19 air filtration guidance (including MERV-13 filters and 6 air changes per hour), urge them to add individual HEPA filtration units to their classrooms. Schools can use their American Rescue Plan funds to help cover these costs.”