One of the reasons masks aren't so effective for the public is the unpleasantness of wearing them for long periods (I have worn several types of mask for whole days sanding fibre-glass and working with epoxy) and the fact that you end up fiddling with them so often adjusting them. And then taking them on and off - if the virus is on the mask, you get it on your hands, and if it's on your hands, you get it on the mask.
If I was the head of a school, I'd probably go against the kids wearing masks. But I'd appreciate parents really thinking it through, and I'd be open to persuasion.
