There are several questions with with the words "high school" and teaching on academia. Can a public school teacher be considered an "academician"? I haven't found any other stackexchange site that is likely to allow for questions about teaching, much less at the secondary level. Has anyone found another site that allow such questions?
Welcome to Academia.SE, this site is about those involved in higher education (postgrad, research etc). There is a Proposal in Area51 for Education.
If your field is in mathematics education, you might want to look at The Mathematics Teaching Community. (But as of now, there is not much activity there.)
Although high school teaching is not on topic at this site, I completely agree that it could be considered "academic" under some interpretations of the word. "Academia" is used here as a single-word summary for the site's topic, and unfortunately it's impossible to find a single word that perfectly fits. No disrespect is meant towards high school teaching, and no implication that it's not really academic. It's just not a particularly natural match for the sort of grad student/professor questions this site is intended for.