I see where Conor Clarke's coming from in his quasi-defense of single-sex education—in theory, it might offer various educational benefits, and some studies show that it might have positive effects on women. But in the real world, it's worth noting that the actual single-sex education proposals out there are being pushed by reactionaries who have no interest in advancing gender equality, and that's why people are concerned. Read the ACLU's challenge to a Louisiana public school district's plan to implement single-sex education in junior high:

Mr. Murphy briefly outlined the differences in instruction that would be given to girls and to boys.

For instance, girls would receive character education and be subject to high expectations both academically and socially. Girls would be taught math through "hands-on" approaches. Field trips, physical movement, and multisensory strategies would be incorporated into girls' classes. Girls would act as mentors for elementary school girls.

On the other hand, boys' teachers would teach and discuss "heroic" behavior and ideas "that show adolescents what it means to truly 'be a man.' Boys' classes would include consistently applied discipline systems and offer tension release strategies. Boys' classes would also feature more group assignments.

The Louisiana plan would put boys in "competitive, high-energy teams" while girls would be "encouraged to take their shoes off." And so on. (Maybe female students can learn math by counting how many shirts they can iron in an hour.) The whole proposal's based on a fairly dubious book about gender differences in education by Leonard Sax. Sorry, whatever the academic studies might say, I can't shake the feeling that, in practice, Louisiana officials are pushing this plan in order to steer female students into home economics classes, de-emphasize real learning, and teach girls how to act like "proper" ladies. Separate but equal, and whatnot. It sounds a bit too much like a Harvey Mansfield wet dream to me...