> Chris Christie said that a national teachers union deserves a “punch in the face”
To be fair, teachers' unions do tend to cause a desire for percussive maintenance. In my own (admittedly anecdotal) observation, said unions tend to be run by - and thus prioritize - tenured teachers over all other factors (including actual approval from students, parents, other faculty, etc., and also including test results, passing rates, etc.). This results in skilled, fresh talent to be the first for consideration when schools need to cut back on teacher employment, rather than the arguably better alternative of encouraging some of the more tenured teachers to retire. This isn't to mention that said unions tend to impose dues regardless of whether or not one is a member, and that said unions frequently take political stances that the dues-payers may or may not agree with.
This isn't to say that the concept of a teachers' union in and of itself is a bad idea - far from it. Rather, in their contemporary form, they seem to be getting more in the way of education (by favoring tenured and perhaps out-of-touch educators over younger, fresher educators with more modern foundations; also, by favoring said tenured and more expensive teachers over younger, less expensive teachers, thus contributing to higher class sizes and thus a degradation of educational quality for students) than they are helping education.
Granted, I'm not really involved in the inner workings of teachers' unions, and my experience is limited to both what I saw as a student and what I continue to see among friends who got into teaching, so maybe these tendencies aren't universal.