That's a tough nut to solve, because by time you find out if quarantine was necessary or not, it's too late. So do we err towards spreading less, or err towards teaching more. It seems difficult to have both.
(Well, we could - replace whiteboards with screens, have the students onsite but the teachers remote. Not sure this is entirely practical?)
It's endemic dude. It doesn't matter if teachers quarantine or not. Social distancing, lockdowns and quarantines have achieved nothing at any point in any of this and Omicron isn't severe enough to justify it anyway. Consider: Sweden is beating the European average for COVID deaths big time and they were always the least into intense countermeasures:
Sweden really does just turn into a "choose your own data" adventure. They have double their neighbours' excess deaths - you really can use them to demonstrate any point you like by picking which data tells the story you want to tell.
No, you cannot, even though people constantly try.
You really need to use all the data for countries that are reasonably western/developed (to avoid Africa with a much younger population and less testing biasing everything). It's all available and there are no valid excuses not to. As I never tire of pointing out, Swedish people aren't aliens and nobody claimed they were before they inconveniently proved the countermeasures weren't warranted. If you use all the data (from developed countries), Sweden ends up way ahead, which is conclusive proof of many things.
(Well, we could - replace whiteboards with screens, have the students onsite but the teachers remote. Not sure this is entirely practical?)