I'm noticing several comments to the effect that "teachers" have some particular qualification to teach that other people don't have. But, at least in the US,

I'm noticing several comments to the effect that "teachers" have some particular qualification to teach that other people don't have. But, at least in the US, the qualifications required to become a teacher are intended to protect the teacher's union and they don't confer any special "teaching ability". People have been teaching things to each other for hundreds of thousands of years, even before there were degree programs in education. I will grant that some people are particularly good at explaining things well, but I don't associate that ability with "public school teacher" in any respect. In fact, it correlates with being bright, which is negatively correlated with being a public school teacher.