There is little to no evidence schools are serious vectors of covid transmission; children are at extraordinarily low risk from covid, far lower than from the flu. If you have evidence to the contrary, please present it. Otherwise, stop shouting SCIENCE! while promoting panic.

The evidence of child-to-adult transmission remains weak; there are a bevy of studies from places ranging from Iceland to Australia to China to this effect. Covid is primarily passed between adults in closed spaces with air conditioning for prolonged periods of time.

If teachers are particularly vulnerable (serious pre-existing condition, age), they probably shouldn't risk being in schools. But that holds true for literally any public place.