I find this trained educator comment awkward. For universities the main thing needed to be a professor is a PhD. While graduate programs will often require some

I find this trained educator comment awkward. For universities the main thing needed to be a professor is a PhD. While graduate programs will often require some amount of TAing (typically two semesters) that's not universally true in the US. You can complete a PhD in some schools without ever TAing. And then as applying to be a professor is judged at most schools mainly by your research and not your teaching experience it is conceivable to teach a class without prior study of teaching. The more typical case is you have been a TA for a couple semesters. I don't really consider that a high bar. My college allowed undergrads to TA for classes and I did that mostly for fun. Is that enough for me to be considered an effective teacher? I'd lean towards no, but it's pretty comparable to what graduate students typically would end up having. As for education at high schools/middle schools, that also really depends. States usually have a teaching certificate/degree as needed, but sometimes a math degree is fine for teaching a math class even if you haven't taken any classes on education. Typically this happens in cases where there's a shortage of teachers for a subject. It doesn't help that a lot of states pay pretty mediocre for teachers. I can say personally one of the high schools I went to, most if not all of the teachers had not done a degree in education and their background was pretty much entirely having studied the associated subject in college. I think for my other high school my teachers typically had education backgrounds, but even there I remember my chemistry teacher did not (she happened to be excellent anyway). My chemistry teacher had a chemical engineer background instead and wound up choosing to teach. Extra anecdote I know my dad has been teaching for decades now as a professor, but back when he got his PhD he never TAed. He had 0 teaching experience/education until he taught his first class. I think TA requirements are less common in europe which is where got his PhD, although he did get it awhile ago so maybe things have changed since then.