There was more than one graph! There were multiple graphs about ages. All showed low transmission under 17-18 (and even sixth forms only have one year group in that range, with most of the range being university age).
I don't have a particular angle on this - I want everyone to be safe, teachers and pupils. But I think all the graphs shown were clear, as well as objective.
I think if we are going to be really cynical, we need to look at why the government is ignoring the huge increase in the age group 18-21 years old, and either telling this age group to behave or locking them inside their halls of residence, but not actually sending them home or closing pubs and bars.
It is like before lockdown when BJ said please don't go to pubs, but didn't close them. The only thing that stopped people going was closing them. It is very tricky politically and economically.
Plus of course the fact that student accommodation is huge business financially and sending the 18-21s home to do their remote learning at home and refunding their accommodation is going to cost someone a lot of money.