@lidlfix this is the problem while NS proudly stood there yesterday and said that schools have had CO2 monitors and they had been improving ventilation....
From friends who are teachers up here they will say bollocks and haven't seen anything as of yet. Ventilation is by far the biggest risk factor now known. Some schools obviously have had this but many are yet to see anything 6 months after it was identified.
A CO2 monitor is a little electrical box which shows parts per million, some will show green, Amber or red depending on levels. Others is a number reading. Under 1000ppm is good ventilation.
I don't think it's teachers who send the messaging out but the unions don't always have the most helpful language, the govt with messaging as well and then media with headlines like covid school etc.
DN is in school in England they don't wear masks in class but do in corridors and Windows are all open.