This measure comes as an effort to keep kids in school following 18 months of online learning and mandatoryquarantining.
According to the CDC’s guidance for K-12 institutions, in-person learning is beneficial for students.
Symptomatic kids would be required to quarantine.

It’s also disruptive for families.
We are going to be following a symptoms-based approach" (viaPeople).
Finally, plenty of Twitter users called for a quarantine of the entire state.
