Just about all schoolteachers are unionized. Some may not be in a recognized organization, but they all stick together if their bennies are threatened.
Gov Scott Walker of Wisonsin showed the country how to put school teachers unions in their place.
You can get out of paying union dues, but still have to pay the portion attributed to negotiations.
But you can bet any teacher even asking about this will be on the administration’s radar, looking for reasons to terminate them.