ln districts across the country, public schools are experimenting with sexual segregation, in the name of school reform. There is no precise tally, in part because schools are wary of drawing attention to classes that may violate gender-bias laws. But, researchers say, in more than a dozen states–including Texas, Colorado, Michigan and Georgia–coed schools are creating single-sex classes. Some, like Marsteller, believe that separating the sexes will eliminate distractions. Others, like Robert Coleman Elementary in Baltimore, made the move primarily to get boys to work harder and tighten up discipline.

The great majority of the experiments are designed to boost girls’ math and science scores. The stimulus for these efforts was a report four years ago from the American Association of University Women, which argued that girls were being shortchanged in public-school classrooms–particularly in math and science. The single-sex classroom, however, is not what the gender-equity researchers involved with AAUW had in mind as a remedy. Their report was meant to help improve coeducation, not dismantle it. Research shows single-sex schools tend to produce girls with more confidence and higher grades. But single-sex classrooms within coed schools? There are no longterm studies of that approach, only a smattering of skeptics and true believers. “It’s a plan that misses two boats,” charges David Sadker, coauthor of “Failing at Fairness” the education of boys, and the reality that children need to learn how to cope in a coed world. In short, says University of Michigan researcher Valerie Lee, “these classes are a bogus answer to a complex problem.”

Critics worry that segregated classes will set back the cause of gender equity just when girls are finally being integrated into all-male academies. Half a century ago, boys in advanced science classes learned, for example, that mold is used for penicillin while girls in home economics learned that mold is the gunk on the shower curtain. “It’s not an era we’re eager to return to,” says Norma Cantu of the U.S. Office of Civil Rights.

Miracles happen: As a general principle, federal law doesn’t permit segregation by sex in the public schools. (Exceptions can be made for singing groups, contact sports and human-sexuality and remedial classes.) Some schools have survived legal challenges by claiming that their all-girl classes fill remedial needs. A middle school in Ventura, Calif., faced down a challenge by changing the name of its all-girl math class to Math PLUS (Power Learning for Underrepresented Students). Enrollment is open to boys, though none has registered yet.

Despite the skeptics, single sex experiments continue to spread. Teachers and students believe they work. At the high school in Presque Isle, Maine, members of the popular all girl algebra class go on to tackle the sciences. University of Maine professor Bonnie Wood found that girls who take the algebra course are twice as likely to enroll in advanced chemistry and college physics than their coed counterparts. Michigan’s Rochester High School turns away 70 students every year from its girls only science and engineering class. Marsteller boys raised their collective average in language arts by one grade after a single term. Girls boosted their science average by .4 of a point.

For the teachers involved, the progress is no mystery. Sheryl Quinlan, who teaches science at Marsteller, knows single-sex classes let her kids think with something besides their hormones. Impressing the opposite sex is a 14-year-old’s reason for being. Take away that pressure, and miracles happen. Quinlan recalls the girl who took a “zero” on her oral report rather than deliver it in front of her boyfriend. Those days are over. Now, says Amanda Drobney, 14, “you can mess up in front of girls, and it’s OK.” We’ve come a long way, babies–or have we?