Informal segregation in schools

Erin and I are proud to call ourselves everyday athletes. We reap the obvious benefits: physical and emotional health; building and maintaining friendships; a greater appreciation for the environment in which we have the privilege of riding and running and playing.
And most of our everyday athlete companions know of our work on gender equity. So on a group charity bike ride last weekend, one of our friends pulled up alongside me and said "Kris, I have to tell you something that happened at our school."
A few weeks ago, the principal at our friend's public school (she is a teacher) divided up the students in the cafeteria at lunch and had them compete to see which group could successfully complete their times tables the fastest. Did the principal divide the children based on their birthday months? Their last names? The color of their shirts?
No, she put the girls against the boys.
Our friend was disgusted. She said she picked up her students after lunch and many were crying. Her experience and her awareness of the problems of pitting boys against girls lead her to a post-lunch talk with her students in which she told them that she thought it was wrong for adults to do that to them. She told them that everyone has different abilities but that they are not based on whether they are boys or girls.
We write a lot about formally segregated classrooms in public schools and the problems and stereotypes engendered and perpetuated by such a system. But gender segregation happens in numerous informal ways every day in public schools. And it is clear that some educators are ignorant of its effects and some have to compensate for this ignorance.
We often wish that administrators in athletics would receive training in gender equity issues. I think I just assumed that teachers-in-training were receiving this kind of education. But maybe not.