What country are you from and do you call it 1) elementary, junior high, high school 2) elementary, middle school, high school, 3) primary, ???, secondary?
Fyi: it's called post secondary because, I think, UK calls it primary, secondary, and after that is post secondary.
US - specifically Michigan. The naming convention and splits most commonplace around me seem to be
Kindergarten - 4th grade | “Elementary School”
5th grade - 8th grade | “Middle School”
9th grade - 12th grade (referred to as Freshman, Sophomore, Junior, Senior years) | “High school”
But there is a bit of variance depending on district size. For example my school district downsized. So currently we have
Kindergarten - 6th grade | “Elementary School”
7th grade - 12th grade | “Secondary School”.
The former setup seems to resemble most of what other Americans would recognize.
Regarding “postsecondary education”, at least here, that specifically refers to any education past the standard 12 year education program, be it medical school or trade school or what we call college and many other places call uni/university.