I have no idea if you’re going to read this or not, but if you didn’t ignore me you’d have read it a week ago. From the CDC explanation of the indicators, bolding in original:
If, after applying the core indicators described in the table below, a school is at “medium,” “higher,” or “highest” risk of transmission, it does not mean that the school cannot re-open for in-person learning
The indicators are a guide to how vigilant the school needs to be, not a method for determining whether they should close or not.
I definitely don’t think “kids don’t spread COVID” but it’s definitely possible and perhaps likely that young kids spread it significantly less. Whether you close schools or not depends on your strategy. Basically my opinion is that if you’re going to accept some level of spread then primary schools are the absolute first place you accept it in, after truly essential services like supermarkets and healthcare. One of the big problems with “the case numbers are very high, quick close schools” is that high case numbers is in itself an indicator of insufficient action elsewhere. My answer to “omg high case numbers, should schools close?” is just “wrong question”.
In Australia, in Victoria schools were closed as part of a hard lockdown and they went for elimination of the virus and got it. In NSW they went more for test-and-trace and didn’t close schools. If you’re just going to allow virtually uncontrolled spread, then modelling from Imperial College, published in BMJ demonstrated that closing schools INCREASED overall mortality, because leaving them open allowed some spread within a non-vulnerable population, creating a mini herd immunity effect which mitigated second and third waves. I don’t think there’s anything like a linear relationship between case numbers and urgency of closing schools, it’s more complicated than that.