As it was pointed out e.g. in the answer of @quid in What are standard assumptions for courses?, the term K-12 is relativly unknown to a large audicene of this site.
What is the most standard and understood term when I want to talk about math educators working in school?
Since ME should not only be about higher education and for professors or university employees, it would be nice to have specific (or at least common) tags for such questions (It seems like the tag
college is the most used to questions not related to school) and maybe also some common ground of the used language (I have no idea if the latter one should be done, and if yes, how this can be done??).