Yep, so let's isolate kids from their working parents too, because that's a pretty obvious way in which they could be exposed to the potential if infinitesimal chance of catching this illness.
Closing schools would be fine if all the schools had measures in place to continue educating all children remotely. The problem is, it seems to be a lottery as to whether your kid gets lessons or not. We've got two teenagers studying A-Levels at different colleges; one college has been on the ball since the start with online classes, but at the other, they don't seem to have any structured lessons for kids studying at home, they're kind of left to study on their own. I hear that's the problem across the country. And with younger kids, I'm not even sure how effective it would be if no one is able to sit down in the same room as them.
The problem with the last 10 months has been this tunnel vision of tackling the virus as though the only thing that matters is minimising the number of people who die within 28 days of a positive test (see what I did there?). But that cannot be the only consideration, we need to carry on living through and after the pandemic. If we stop educating children, that will do wider and more long term damage than Covid-19 ever will.