So, sure, there are some bright and knowledgeable teachers out there. But the test scores and admissions requirements tell an important story: as a whole, the US teacher corps is not super-intelligent or super-knowledgeable.
You could make the same (bolded) statement about just about any group in the US. Also, I don't think the GRE measures on education majors apply very well beyond elementary school, because in junior high and high school you start running into teachers who majored in the subject they're teaching (or something very much like it), and then tacked on the teaching credentials. You also encounter people teaching vocational classes, home ec, and PE.
Given the basic levels of instruction involved, I don't expect a K-3 teacher to have much more than a high school education. There's no calculus involved in understanding place value.
I think we agree that the people teaching foundational skills can make mistakes when they misrepresent concepts which force students to unlearn at higher academic levels, but this is where academia is supposed to be partnering with educators to make sure the curriculum lines up. And to me, that's the real problem... academia is almost completely absent from the scene, having been pushed out by Big Publishing.
