Masks save lives if you cannot social distance more than 2m all the time and indoors. The success rates that densely populated nations like Taiwan and Hong Kong have achieved in keeping Covid infection and death rates way down and having only minimal disruptions to schooling demonstrate that masks save lives.
Since so many secondary schools and senior schools have been making visors for GPs, nurses, physios etc for free while Matt Hancock has been hanging on to our taxpayers' funds instead of buying PPE with them, it makes sense for the DT departments to continue making visors- this time for their own teaching staff and other school staff. It makes no sense to carry out charitable deeds for others while neglecting your own school. If teachers get ill with Covid and die (like the primary school teacher in Israel did after catching it in her school) or become chronically ill and unavailable to teach, all pupils suffer.
Visors make it possible to teach while giving teachers protection. In some countries, younger pupils have been given washable (reusable) visors to wear at school and this has worked very well in terms of being able to speak and be heard as well as causing less discomfort.
We met four other students, socially distanced and within government guidelines, outside, just before term started. All teens and they were the best at putting their masks on, more so than the parents (only half had masks). People who automatically say secondary school pupils cannot be trusted to behave are clueless about how knowledgeable and sensible teens are. They've had 6 months of either isolation or misery or both. Even daily binges of Fortnite or Grand Theft Auto at home begins to get boring when you can't see your friends or do normal, fun things whether that's school, football or clubs. Others have had their lives thrown into upheaval by GCSE disruptions and watched their older peers being put through hell over the A level.fiasco. They're not about to take risks with their lives. The teens and children I've come across have actually been the most responsible about Covid safety behaviour. Not wearing masks is a bit like not wearing your seatbelt while driving because "it doesn't protect you from every single accident". Yes, it doesn't but it protects you from dying in a lot of accidents. Your "rights" are quite useless when you join the over 42,000 dead from Covid (as the bereaved family members of several high profile Covid deniers in the US have discovered).