When Bonnie Becker was in grade school, it was the boys in her class, 10 and 11 years old, who stood at intersections near the school proudly wearing the white chest belt that distinguished them as members of the traffic patrol, entrusted with the safety of their schoolmates.

In those days, none of the 10- or 11-year-old girls got to wear the belts.

"I didn't really want to stand out in those cold Illinois winters," recalls Becker, a Fairfax County human relations officer, "but I at least wanted to have a choice."

Since 1972, however, school systems that exclude either sex from the school patrol or from most clubs, teams and classes can be denied federal funds -- and slapped with a lawsuit -- for violating restrictions on sex discrimination spelled out in Title IX of the Education Amendments.

So far, the response of school systems, teachers and parents to the sex discrimination issue has been varied. Nevertheless, leaders in the sometimes slow and uphill struggle for sex equity in the classroom have begun counting their first victories.

"Girls' participation in interscholastic sports has increased over 500 percent, and enrollment in engineering schools has increased over 1,000 percent," says Myra Sadker, dean of American University's School of Education. She is a co-researcher on sex bias in schools with her husband, David, who is director of the Mid-Atlantic Center for Sex Equity at American University.

"We are also hearing of the first boy to win a Future Homemakers award in one state and of a girl elected president of a state-wide industrial club."

Textbooks have been another area of dramatic change, adds Becker, who serves as watchdog against sex discrimination in Fairfax's 160 schools. Although instructional materials are not covered in Title IX, Becker's office sits on textbook review committees to weed out books considered promoting discrimination. Among them: "Textbooks that don't mention women at all, and stories that show girls needing to be rescued or waiting at home while their brothers play soccer . . .

"Adventure stories almost always cast boys as the protagonist Nancy Drew being one exception ," Becker says, "and as a result, girls will read anything, but boys won't read books about girls.

"We are not in the business of book burning, but if there is a choice between a book that stereotypes either sex and another book that opens options for children, we'll choose the latter."

Even with these changes, it is sometimes the students themselves who are hesitant to venture into non-traditional areas for their sex. Auto body repair classes are open to females but many remain all-male. Often only a handful of girls show up to try out for a sports team compared to crowds of their brothers and boyfriends competing for a place on the roster.

Teachers also are finding it difficult to remodel their behavior to change the often subtle ways they may be promoting sex stereotyping.

"Most people, including teachers, will say that if any favoritism is shown in the classroom, it is towards girls," explains David Sadker, who with his wife has been observing teachers in hundreds of classrooms in a sex-bias research project. "But our studies have shown that teachers talk more to boys, give them more counseling, ask them more questions, provide them more direction and give them more attention in general."

"If you sit in the teachers' lounge and listen to who is described as an outstanding student, it is usually a boy," says Myra Sadker, who once taught the 7th grade. "The humorous anecdotes and even the tales of discipline problems also feature boys. Girls, in contrast, appear to be invisible."

"One hypothesis is that this is happening because boys are valued more," says David Sadker. "Traditionally they are the ones who are destined for important jobs and who have higher social status. So, when teachers praise students, they tell Mike he gave an excellent analysis of the Civil War, and they tell Jennifer she has lovely handwriting.

"If a student makes a mistake, the boys are told, 'Try again,' and the girls are told, 'You didn't do it right.'

"Even at the pre-school level," Sadker says, "if you watch children take an Easter basket to their teacher for help in attaching a handle, she is likely to tell the boys where the stapler is and do the stapling for the girls. As a result, the girls get short-circuited."

However, he notes, "Boys are more likely to be scolded and reprimanded in classrooms, even when both boys and girls are misbehaving. This hurts boys, but it also hurts girls, because they are not held as accountable.

Many teachers, say Becker and the Sadkers, may not even be aware of how school children are segregated by sex.

"We accept a girls-against-the-boys spelling bee as a matter of course, but can you imagine the reaction if it was the Christians against the Jews?" asks Myra Sadker. "Yet, it is really the same thing."

Children as early as first grade initiate their own self-segregation by insisting on sitting with same-sex classmates at the lunch table. The declaration that "girls are yucky" may be a carefully mimicked line from an older brother, which serves to pass segregation norms down through the grades.

"Once teachers become aware of how they perpetuate these norms, most want to change," says David Sadker. The American University Center for Sex Equity offers teacher workshops on avoiding classroom bias, but "if you have been unconsciously inequitable for 10 years, it is not easy to switch that pattern."

Some school systems are going beyond what the law requires to combat sex discrimination. Falls Church, for example, offered to the city's 90 teachers a 48-hour workshop on sex equity -- including such aspects as math anxiety (usually experienced by girls) and women in history.

Such an extensive program may not be as feasible in such large systems as Fairfax County's with 7,000 teachers. But Becker says she tries to "incorporate these ideas into teachers' in-service sessions, whether they are on new curriculum or on behavior management."

Ultimately, say the Sadkers, the change has to begin in college education programs. In a line-by-line study of the 24 leading education textbooks, they found "sex equity is a missing issue."

"It's important that the colleges where teachers are trained stress sex equity so we can break the self-perpetuating cycle of sex discrimination," says Myra Sadker.

"And," adds her husband, "we also need the moral and financial force of the federal government, which historically has helped bring about social change."