To avoid quarantining students, a school district tries moving them around every 15 minutes.

To reduce the number of students sent home to quarantine after exposure to the coronavirus, the Billings Public Schools, the largest school district in Montana, came up with an idea that has public health experts shaking their heads: Reshuffling students in the classroom four times an hour.

source https://www.nytimes.com/2020/10/20/us/billings-schools-montana-covid.html