> As Carrol has regularly argued, I think, most teachers in most schools in most communities since the start of mandatory public education were only moderately well-versed in the material they taught and even less well prepared to teach anything well.
I'm not sure about most. What about the decades long period when u.s. public education relied on exploitation of women? A lot of talented women were teaching school when other jobs were closed to them. And they had long careers too. My fourth grade teacher taught me *and* my mother.