Basically, some simulations show [1] if lots of people from an otherwise-socially-distancing population all go to one central location, that increases the R0 (i.e. spread) of the virus.

This is a problem for anything that draws together lots of people from a large area into the same place - trade shows, sports events, music festivals, cinemas, conventions, busses and trains, food stores, beaches, universities and schools.

We almost certainly haven't hit on the most optimal solution - in my country we closed schools, yet keeping crowded metro trains running? - but it wouldn't have been wise to wait for more data to come in before taking any action.

[1] https://youtu.be/gxAaO2rsdIs?t=1010

A five year old with pre-existing conditions sadly died, and some babies have died in the US, but the risk to children is thankfully very very low (percentages tend to 0% for that cohort at present the deaths are so rare), and infections among children are probably being massively undercounted.

Kids can get infected although at a lower rate under 15.

So yeah and essentially that by keeping contact limited if someone does get sick you only need to quarantine a limited set of people and close a classroom rather than the whole school. I feel like a lot of the success here has been in being aggressive with contact tracing and people able to take the social responsibility to self-quarantine.

For primary age children at least, though, there will be roughly one parent/carer per child gathered outside the school gates, which has to be a major source of adult transmission.

Here we are all standing well apart and the kids are let out one classroom at a time.

Or other children and their family etc.