There is very little evidence of infection of people who are exposed at school and proceed to quarantine at home

See Fully Opening Schools Is Urgent. Here’s How to Do It by Emily Oster. Excerpt:

"But some data has suggested there is very little evidence of infection of people who are exposed at school and proceed to quarantine at home. If this finding holds more broadly, it’s possible we might limit quarantines to people who’ve been in close contact with someone with Covid, or shorten the length of quarantines, in conjunction with testing and monitoring. Cohorts enable schools to limit interactions among students and staff, which makes it easier to conduct contact tracing when Covid-19 cases do emerge. Pods, or even just smaller class sizes, can also help by limiting how many people need to quarantine."