Wow, sorry I'd not responded, I've been at work and not noticed this thread moving on..
The measures in place in my children's secondary school were:
Masks in corridors, sanctions if not worn, consistently applied.
Windows open
Teachers in taped off area 2m away from closest desk
Work (and homework) handed in electronically and marked/returned electronically.
Online parents evenings/parent teacher meetings/pta meetings
Clubs restricted to single year group only
Assemblies restricted to single year group only and no singing
Year bubbles, no mixing of children between years
No sharing of resources
School zoned, with zones allocated to just one year group.
Teachers moving between zones, children stay in zone.
Sports fixtures against other schools cancelled
No contact sports
No swimming
Staggered start and leave times for year groups
School buses at half capacity
Individual music tuition moved online
Orchestra cancelled
School production cancelled
Hand gels outside each classroom and children encouraged to use
Reminders re handwashing and social distancing
Zero tolerance of children in school with symptoms
All lessons also simultaneously streamed remotely if any child at home self isolating
Increased cleaning frequency
Wearing in of PE kit on games days so not crammed into changing rooms
Cafeteria staff wearing masks and gloves (think gloves is normal practice in non CV anyway)
And probably a few others that I've forgotten.
Zero cases ever in my children's school, staff or children. SE England.
I feel it was safe, and the school took good precautions to keep it so.
Once community transmission became so high, it was shut (the ultimate mitigating factor), because it was no longer safe, due to the rate of transmission in the community.
Noble giraffes graphs/ info show that rates in children were high in the latter part of the year. Community transmission was high. We needed to shut schools at that point. I've never disputed that.
When rates are down in the community, schools will be safe to reopen again, with mitigation factors such as the ones listed above.