[aianus]

You may be right about elementary school teachers, I'm thinking more about high school STEM teachers specifically. Although the grade school teachers in my city seem to struggle even with fractions [0].

Only one of my high school math teachers seemed to have any idea what math was about (not just regurgitating formulas, but deriving them and proving them from a set of axioms and only then using those formulas to solve free-form real-world problems).

My High School CS teacher was a geography teacher who just read one chapter ahead in the CS textbook and had no idea what he was talking about.

Being good at teaching seems kind of useless when you don't know anything to teach.

[0] https://www.thestar.com/yourtoronto/education/2016/05/13/for...