The New York Times Magazine ran a very long piece on single-sex education in public schools on Sunday. In short, there seem to be five positions explored: some argue that boys' brains differ fundamentally from girls' brains and that, therefore, they should be separated; some argue that separation is merited in order to end discrimination; some argue that separation is inherently sexist; some argue that separation by gender is only a rough proxy for separation by learning style; and some argue that boys and girls need to interact with each other.
I think each of the five sides has some merit. When this issue came up in our sociology class last year there was some spirited debate, particularly since research has been inconclusive to date. I asked people if research conclusively proved that single-sex schools led to much higher test scores if they would then be willing to enroll their children in these schools; nobody was willing to commit. This says two things to me: that there's more to a good school than high test scores, and that there's something less easily describable driving the opposition to such schools. Personally, I would hesitate to send my (future) children to such a school.
Prior to teaching I would have unequivocally ruled out the idea without so much as a second thought, but my experience led me to reconsider the merits. Teaching sixth graders, I noticed substantial differences between the boys and girls in my class. My personality and teaching style clearly worked better with the girls, and I had significantly more discipline problems with the girls. Maybe it was just the stress, but it often seemed that teaching a class of only girls would've worked a lot better. That said, segregating by sex still seems wrong to me on some level. I wonder if it might be possible to experience the best of both worlds; perhaps have single-sex classes only during middle school or only for certain subjects or activities. Or maybe Jay Giedd is right; gender is too rough a proxy. Has anybody tried separating students into classes based on different styles of learning? Is that feasible or desirable? It would certainly be easier for teachers than the "differentiated instruction" that is currently pushed, but I'm skeptical of any cure-all, especially one that requires some form of segregation or tracking.