Fully appreciate that but you do understand the primary transmission is through prolonged contact in same space via the air, and there's very little protection to anyone wearing anything other than n95 masks?
There's a reason supermarkets have hand sanitisers on entry and for use by staff, they can mitigate their risks to infection hugely by effective hand hygiene. You can't do that to the same extent if you're in an enclosed space with an infected person without a n95 mask. There's massive dilution of the viral load in a supermarket because of the size of the environment and number of people in there. School's classroom are probably more densely populated and people are stationary, for long periods, potentially expelling a large viral load in the same space.