@LadyofTheManners They have been no recorded cases anywhere of pupil to teacher transmission.
Most cases don't have evidence of where they originated, so that's not really significant.
But schools have been closed to most students, and many staff have been following government guidelines to work at home the majority of thr time, so transmission has been hugely lowered inside school buildings.
When they're full again, with no distancing, the numbers will clearly change. Transmission hasn't been absent anywhere populated with people.