DS1 has autism and dyspraxia. He had to wear a face covering for a medical appointment last week. I was actually surprised that he gave it a try as we gave up on the trauma of wearing trousers years ago. Good luck to any teacher trying to teach him with a buff pulled over his entire face. Then he was pulling it around, peeping through it, hands all over it. Absolutely pointless from any hygiene point of view.
There is no way that he can hygienically manage face covering in a classroom and not be a fidgety distraction to others.
He has reasonable exemptions to not wear one. But as a child who can generally mask as neurotypical and whose recent diagnosis is not widely known, how does teacher explain that he has a reasonable exemption and the rest have to suck it up.
How does he communicate with his classmates when he can't manually process their expressions and non-verbal communication that most people would take for granted anyway. Plus the verbal processing of muffled speech. Plus the eye contact issue where he can't focus on any other part of the face to mitigate the fact that he can only cope with eye contact from very few trusted people.
Basically pretty much every class has children like DS who are exempt and are massively, massively disadvantaged by other people having to wear them, on top of home learning having been a faliure because of their SNs. Remember SNs are no reflection on intelligence either.
Thank goodness that I no longer teach and will not have to face a room of masked teenagers. Covered faces for a significant minority will be a liscence for concealed disruption. Whispering or with minimal visible facial movement would be very difficult to manage and deal with. At least flinging masks for the "Ewww!" factor is a bit easier to pin down.
Plus there's the process of matching names to faces which takes time anyway. In my foundation subject, at KS3 I saw pupils for far less time in one school year than a primary teacher sees their class in a fortnight. Trying to recognise 15+ classes of pupils in identical clothes with half the face covered would be a logistical nightmare for teachers trying to learn names and get to know pupils.
Then there's the communication/ speech/ hearing difficulties.
Children dealing with steamed up glasses.
Not all pupils will be happy to return to classrooms after nearly 6 months. Many will have had very few boundaries in that time. Many had low motivation to learn in the the first place. This section of the cohort will relish the extra opportunities to liven up a lesson with concealed disruption to the detriment of everyone else.
The evidence of masks being protective in a classroom environment is poor and massively outweighed by the catalogue of obstructions to learning that they will cause to vast numbers of children.