They have also advocated clearer school routines, more traditional school structures, including single-sex classes, and stricter discipline.

However, the experiment showed that while single-sex classes for girls led to better exam scores, there was no significant effect on their coursework marks.

Boys and girls are taught in single-sex classes from the time they leave the Nursery.

"We could not allow the district to run single-sex classes," Ms. Okum said.

Still a Few Stars In most of the single-sex classes, everybody raised a hand and had a say.

Girls do significantly better in single-sex classes, research claimed today.

"The use of single-sex classes and schools can reflect important and legitimate efforts to improve educational outcomes for all students," the notice said.

The Bush administration is encouraging single-sex classes and schools in the public sector, where civil rights laws have sometimes halted such experiments.

If this happens, the simple fact of shifting to single-sex classes is unlikely to benefit girls.

To encourage physical fitness among high school students we must provide an unthreatening environment, including single-sex classes for those who prefer them.