It was much more dangerous before schools closed and there hasn't been any mass cases linked to schools that I'm aware of? We live in a hotspot, I know teachers at a number of schools in the area and no one has heard of any cases at all.
The R. number is falling, if it continues to fall then it should hopefully be safer than March.
A point about R.
R can be rising and there be less cases than if its falling.
It can be R3 but only 300 have it.
You then close and the R reduces and eventually then starts to fall below 1.
But during the period you were shut if there was sustained infection above 1 for long enough you could still, several weeks later when the R was below 1, have more than the 300 cases at the point of lockdown.
Thus the R falling does not necessarily indicate that less people have the disease.
The risk of catching the disease is a combination of the risk of exposure through lack of distancing, hygiene etc but also about the number of people who are carrying it.
You can have a higher R value but still be at less risk than a low r value if the number of people carrying the disease is higher.
This is why the government requires sustained drop in the R because its ultimately about the number of people infected as much as the R itself.
And the R can vary hugely in very small areas. Hotspots can be missed without proper contact tracing. Which we do not have.
Schools therefore act as a barometer for locating hotspots in the absence of proper tracing ability. And that's really not a fair way to identify areas where there is a problem still.
So my point is that don't use the R alone as a way of understanding the risk. It's not enough.