NEW YORK — An all-girls school? Leslie Cortez says her friends in Harlem thought the idea sounded crazy. She politely set them straight.
"Girls and boys may need time apart," the tall seventh-grader says matter-of-factly. "Boys are noisier; they're more into girls and fashion. At my age, I need to focus on my studies."
This week, Leslie and some 40 other girls will don navy blazers and checked skirts and step into a school of their own. The Young Women's Leadership School in east Harlem, the first all-girls public school to open in the United States this century, begins classes Sept. 4 - despite a barrage of criticism and a civil rights lawsuit.
The school in Harlem is part of a scattered but decided comeback for single-sex education that extends from the potato fields of Maine to the palm-lined streets of California. While the Harlem school is one of only three public schools for girls in the nation, educators note that enrollment at private girls schools has jumped 8 percent since 1991.
Efforts have been launched, too, to set up public schools for inner-city boys in Detroit, Milwaukee, and New York. But they have been halted by lawsuits on grounds of gender discrimination.
Driving the movement toward single-sex schools - or even single-sex classrooms at coeducational schools - are a handful of studies that indicate boys and girls have different learning needs and receive unequal treatment from teachers. The impetus for this approach to education received a boost in recent years, especially after a widely publicized study in 1992 reported that bias against girls persists in America's elementary and secondary schools.
Creating same-gender schools like the one in Harlem is a cheap and easy way to provide more options for students, says Kathy Christie of the Education Commission of the States, an independent think tank in Denver. "People are saying, 'If it works, let's do it.' "
"Of course, there's not a lot of data on how it works when it is done," she adds. "But hey, it's not costly and it's not divisive - if it's handled properly."
Research on public single-sex programs is scant at best, but private schools offer a window on their possible effectiveness. In one recent study, African-American and Hispanic students in private single-sex schools scored nearly a year ahead of their peers in public co-ed schools. The finding applies to students at all-girl and all-boy schools.
But these results don't necessarily mean that all schools should switch to a single-sex format. In fact, such schools may be more effective when they are atypical, says Cornelius Riordan, a professor who conducted the study for Providence College in Rhode Island. "The more that these schools remain rare and special, the more effective they will be" for that minority of students who select them, he concluded in the study.
For girls, in particular, same-gender schools may prove to be valuable. Studies show the traditional public-school system underserves girls, catering to the learning style, the temperaments, and even the sports metaphors of boys. Girls receive less attention than boys in a co-ed setting, and their test scores steadily decline in higher math and science classes.
"In general, girls are competitive, but they are collaborative," says Whitney Ransome, director of the 80-member National Coalition of Girls Schools in Concord, Mass. "They think about how to solve a problem together rather than try to do it ahead of the other guy."
"It's not that Billy is deliberately trying to keep Betty off of the computer" in a co-ed classroom, she adds, "but someone in charge of the classroom needs to take note and make some changes. Perhaps [co-ed schools] need a girls-only time in the computer lab. That's easy to do."
But some educators say that any form of separation based on gender or race is flawed, even when it is done with good intentions.
"Obviously, we need to overcome some of the negative experience that black males [and minority females] are having in the present school system," says Charles Willie, a professor at Harvard University in Cambridge, Mass., who adds that the effectiveness of single-sex schools is not proved. "But I object to experimenting on people who can't protect themselves ... without adequate data on the possible effects."
In legal terms, separating boys from girls is just as indefensible as separating blacks from whites, says Norman Siegel of the New York Civil Liberties Union, which has joined the local chapter of the National Organization for Women and other groups in filing a complaint against the Harlem school.
"In general as a society, we have supported integrated education," he says. "More than four decades ago, the Supreme Court said that separate is inherently unequal."
No federal law specifically bans public single-sex schools. A 1972 law, however, prohibits discrimination on the basis of gender in educational programs receiving federal financial assistance. But even under this law, school districts may set up comparable and separate facilities and courses for boys and girls. But the US Supreme Court has consistently ruled against separate schools, from the famous segregation case of Brown v. the Board of Education to the more recent ruling against the all-male Virginia Military Institute.
The Harlem school could avoid a contentious court fight by opening the admission process to boys, says Mr. Siegel.
The bottom line, he says, is that "if there is evidence that girls are underserved or that there is a behavior problem with boys ... then teachers should improve the integrated model rather than institutionalize the segregated model."
SOME people who support same-gender schools argue that it is harder to reform the nation's entire school system than it is to tinker with a few models that address specific problems.
"To a certain extent, you can't teach an old dog new tricks," says Ann Rubinstein-Tisch, who helped launch the Harlem school with her husband, Andrew Tisch, an executive of the Loews Corporation. "Some of us are aware of the problem, and some of us aren't. In the meantime, we are helping parents provide a choice" within the public school system.
In Harlem, Leslie and her mother, Leonides Cortez, hope the school year won't be interrupted by a court injunction. Mrs. Cortez understands the concern of civil libertarians, but she says it's time for drastic measures. "I always tell my children that just because you live in a poor area doesn't mean you can't reach for the stars," she says, seated in a freshly painted room at the Young Women's Leadership School. Setting up this school may break the spirit of integration, she admits, "but now we have to sit back and say we've done all this [integration], and we're still in the same spot."
For her part, Leslie says she's confident that civil libertarians and lawyers will sort out the legal issues and keep the nation from returning to the days of Jim Crow. In the meantime, she says, "One small girls school in Harlem is not going to separate the whole nation."