Have you noticed that the trendiest curriculum for education reformers seems to be astronomy? These days, when politicians try to fix the problem of inadequate or unequal schools, they want to send the girls to P.S. Venus and the boys to P.S. Mars.

The growing popularity of sex-segregated schools and classrooms is evidenced everywhere from New York to California. Indeed in California, where the state is putting serious money into this idea, some of newly segregated students sounded like gender aliens:One sixth-grade girl entering a new single-sex class said: "Boys are loud, and they get all the attention." A boy in a parallel all-male school universe said, "Girls get you in trouble and make fun of you if you get the answer wrong."

The romance with segregation as the cure for rambunctious boys and math-phobic girls began its ascent into the heavens with an inadvertent boost from a 1992 report by the American Association of University Women titled "How Schools Shortchange Girls."

That report showed that girls were not called on enough or encouraged to do science and math. It was followed in 1995 by another AAUW report on the pervasiveness of sexual harassment in schools.

The combination was enough to send a lot of parents, pols and educators intergalactic. Since then, the most bandied-about "new" idea has been to separate the boys and the girls.

Now the AAUW has done another orbit in this debate and come back with a new report released Thursday on single-sex classes and schools. It turns out that the interest in P.S. Mars and P.S. Venus is less like astronomy and more like astrology. There are a whole lot of true believers and not much scientific backing.

Gathering as much evidence and as many experts as possible, the AAUW found no proof that segregated schools or classrooms work better in general than coed. In the succinct phrase of Janice Weinman, the AAUW's executive director, "The bottom line is that single sex-education does not make the difference in terms of girls' success."

The only students who do better academically in single-sex settings are the disadvantaged. Even then, when girls do better, say, in math or science, it's likely to be for reasons other than gender: small classes, strong academic programs, teacher commitment and lots of parental involvement. This is also true for all-boys classes.

Most of the single-sex schools in the country and in the study are still Catholic or private schools. The real reason students perform better is that they have "pro-academic" parents who deliberately selected such schools.

As for gender equity? All-girls schools are not necessarily less sexist. Nor, for sure, are all-boys schools. Ironically for those who care about girls and boys, when you take girls out of the classroom mix, the school may get worse for many boys who get picked on in place of female targets.

All-girls schools do seem to provide some adolescents with a "safe environment" for learning. That's real. But we have to ask whether this "protection" defines girls as helpless victims and prevents them from learning to fight back. Does this "alternative" allow schools to forget about providing a safe environment for everyone?

This report is going to prick a lot of pop notions and pop politics. Single-sex education has gotten a good rap because it appeals to both those who think we are hopelessly opposite sexes and those who want some - any - quick fix on the path to gender equality and quality education.

Patricia Campbell, who co-authored the first AAUW study and contributed to this one, says, "The goals of many people working on single-sex classrooms are really laudable. It's hard to change the educational system, or to figure out how to make the classroom the way it should be. It's not hard to say `boys to the left, girls to the right.'

"It's a fairly quick and fairly cheap way to get a political solution. But it doesn't solve the problem," she adds, with a burst of unteacherly grammar, "It ain't working."

This is not a cry against single-sex classes and schools. They remain rich experimental grounds and alternatives. But in the end, 95 percent of students remain and will remain in coed classrooms. This is where the work is to be done.

The latest report will leave anyone skeptical about putting too much of the public hope or education money into P.S. Mars and P.S. Venus. The fault, it seems, is not in the stars.

The Boston Globe Newspaper Company