Virginia Postrel writes that smart women who were shut out of the professions used to become teachers. That was bad for the women but good for their students. New York Times:
The best female students – those whose test scores put them in the top 10 percent of their high school classes – are much less likely to become teachers today.
“Whereas close to 20 percent of females in the top decile in 1964 chose teaching as a profession,” making it their top choice, the economists write, “only 3.7 percent of top decile females were teaching in 1992,” making teachers about as common as lawyers in this group.
So the chances of getting a really smart teacher have gone down substantially. In 1964, more than one out of five young female teachers came from the top 10 percent of their high school classes. By 2000, that number had dropped to just over one in 10.
Women who do become teachers, however, are better educated today than in earlier years so rather than a total dumbing down there has been a trend towards mediocrity.
Merit pay would lead to better teachers but it is opposed by unions.
This is from the ever-wise Virginia Postrel, NYT password required. Here is a link to the original research. Caroline Hoxby argues that wage compression, often brought on by unionization, is responsible for three-quarters of the decline in the aptitude of female teachers.