are teachers too easily caught in the crossfire?

Well, are there ineffective teachers? I'm sure there must be. I've heard stories of ineffective teachers. And I certainly don't think there should be even one ineffective teacher in any school.
And it's the job of the administration, the job of the principal primarily, to make sure that no ineffective teacher ever gets tenure. Once they get tenure, all that means is -- it doesn't mean they have a lifetime job. It doesn't mean they get paid for breathing. It means that they have a right to due process. If, after getting tenure, the principal says, I want to fire you, they have to have evidence. They have to have a hearing before an impartial administrator.

That really is not such a burdensome thing. But it's very clear that this is not the key problem in American education, because the lowest performance is not in union districts. The highest performance in America is Massachusetts, Connecticut and New Jersey. These are three states that are all union states.

They have very strong collective bargaining agreements and the highest-performing states. The weakest performance is in the states that have no collective bargaining and where there's a lot of poverty. I think it's really important in your discussions about education that you recognize that the most -- the biggest single correlate and, very likely, I would say the cause of low performance is not teachers or union contracts. It's poverty and racial isolation.

-- PBS interview with Diane Ravitch