Evanston Township High School is so big that the administration has put up locator maps with "you-are-here" markers to help people find their way around.

It is so big that a senior, relaxing in the upper-class lounge, points out two classmates whose names he still does not know.

Enrollment at Evanston, which reached nearly 6,000 students in the early 1970s, is down to "only" 3,500, but crowds of youngsters still throng the long corridors and pour onto the acres of athletic fields in a seemingly endless stream.

Such large, comprehensive high schools have long been held up as models for the nation to copy. When, 23 years ago, the late Harvard president James Bryant Conant drafted his landmark educational blueprint known as the Conant Report, he called for bigger and better high schools and even urged that small high schools be "eliminated on a nationwide basis."

Evanston still fits the Conant model. It is a vast, diverse institution serving the children of Chicago bankers from expensive homes along Lake Michigan, of blue-collar "ethnics" from local plants and of blacks whose homes cluster around the school. Evanston has something for all this mixed clientele. The gleaming domed roof of the planetarium beckons the budding astronomer. For the vocationally minded there are classes in everything from cosmetology to welding, and the academically gifted can choose from a menu that ranges from advanced Hebrew to multivariable calculus.

But is Evanston High still a model for the future? Or is it an anachronism, an idea that no longer works? The answer has application everywhere in America, for the Conant ideal was the model for a generation of large new high schools in the suburbs, including many in the Maryland and Virginia suburbs of Washington.

Conant, who died in 1978, saw such institutions as "vast instruments of American democracy," gateways to opportunity that promoted social cohesion in a nation of many economic classes, cultures and peoples.

As the 1980s begin, however, Conant's views are being challenged across a broad front. Prestigious studies have piled up in the last decade questioning his "large schools" vision, and even his assumption that the American high school was fundamentally sound.

A Carnegie Council study on youth, issued in 1979, called for "breaking up the big, monolithic high school and its deadly, weekly routine," a thrust that went straight to the heart of the Conant position.

James S. Coleman, the University of Chicago sociologist who has authored several major studies of schools and youth, also leans toward fundamental change.

"The American high school was built on the assumption that the family had the main responsibility for the education and development of children. With the changes that have taken place in society, that assumption is not necessarily valid. Therefore we either must change the family or we must reshape the high school to the actual reality," Coleman says.

A study sponsored in 1973 by the Charles F. Kettering Foundation declared that it was "past time for national goals that will give the schools a new alignment to the needs of the society."

When Conant wrote his 1957 study, "The American High School Today," he made clear that the high school was the best hope for easing the divisive forces in the society. This alone justified strengthening the public school to attract the "best minds." Contact between races and classes in a high school setting, he believed, would round off the sharp edges between groups. Yet today the high school has become a social battleground that seems rather to have added to tensions.

As middle-class families have deserted city schools, the society has moved toward the thing Conant feared more than anything -- a dual system of education for the poor and nonpoor.

"We are in danger of developing a permanent underclass, a self-perpetuating 'lumpen proletariat' in the home of opportunity," last year's Carnegie study concluded.

Most of the major studies that have been done on high schools in the last decade have recommended more "alternative" programs, stronger connections to communities and the adult work place. The Carnegie study, titled "Giving Youth a Better Chance," concluded that formal schooling could be cut back to three days a week without loss of achievement. Coleman's study in 1974 called for high school programs that eased the transition from academics to the work place. The Kettering Foundation study urged more "nonformal" programs.

Moreover, there has been agreement among the reformers that many schools are too large. The nation's 13.2 million public high school students attend about 20,000 high schools. About a quarter of these schools, with more than half the total enrollment, have more than 1,500 students, and 12 percent of the schools have more than 3,000.

"I would say that those over 3,000 are too large for the majority of the youngsters in them," says Scott Thomson, who represents the national association of high school principals in Washington. Thomson, who was superintendent at Evanston from 1968 to 1974, says that smaller schools have "some advantages in terms of human development," and adds that there is no evidence of differences in academic achievement between large and small schools.

But Evanston's current superintendent, Nathaniel Ober, who worked with Conant on the 1957 study, contends that much of the criticism traces back to the turmoil of the early 1970s and a desire by school administrators to get "control" over their students.

Teen-agers, he says, sense that schools don't serve their needs, that "they're being locked up in these institutions not for their own good but to get them out of the home until they're old enough to be employed."

In one sense, the debate over the role of the high school is typical of the institution's stormy history.

The modern American high school is less than a century old, and in its brief lifespan its objectives have shifted frequently. At the turn of the century less than 6 percent of all youths attended high school, and most who did went on to college. As enrollments swelled rapidly through the 1930s, high schools increasingly became gateways to jobs and opportunity. In the last two decades they were central in the struggle to achieve racial equality.

But in another sense, the pressures on the schools today are unique. For better or worse, educators agree, children today have been raised differently than their parents. One child in five now lives with only one parent and the influences on children include television programs and commercials, magazines and the pervasive drug culture as well as families and teachers.

Whether this is good or bad is a matter of intense debate.

"We have a rising incidence of teenage pregnancy, veneral disease, truancy assaults on teachers and drug and alcohol abuse. Those are facts. It's up to the public to judge whether that constitutes a youth problem," says Terry Herndon, executive director of the National Education Association.

On the other hand, Gallup surveys of teen-age attitudes turn up evidence that youthful values may not have changed as much as some adults imagine. These show that a majority of teenagers fear violence at school, oppose legalized marijuana, say they watch too much television and would like more homework.

In Ober's view, the adult world's perception of youth and of schools has been skewed by "a deep-seated dislike of youth that has grown up in our society in the last 30 years."

"The groups we demean the most in our society are the poor, the black, the female and the young," he goes on. "The community exploits youth but it doesn't really like youth. And there are more youth today -- that's part of the problem. The biggest problem isn't the schools but the second-class citizenry of young people that has grown to tragically large proportions."

That a large school such as Evanston works for at least some teen-agers is evident here.

"I loved coming to a big school," said Janet Bixby, a senior who is on the student council and the girls' volleyball team. "Sure it's big but there are so many things to do. You just find something and that's your base. At this place everyday is different."

Evanston High is in the process of going full circle. In 1967, to cope with burgeoning enrollments, the school was divided into four subschools and a "module" curriculum was introduced that allowed students a free hand in allocating their time. From 1968 to 1971 the school was caught up in the wave of black militancy, student activism and drug experimentation that swept the whole country. Between 1974 and 1980 the superintendent's job changed hands four times.

When Ober took over he reintroduced study halls, reconsolidated the top three grades and generally tightened up. He felt that the four schools hadn't developed an identity of their own and that the system of independent study had led to discipline problems, with kids congregating in corridors and cafeteria. This year, you can hear a pin drop in the corridors during classes and Ober, a tall, bearded man, jokes that "they can't tell whether I'm an overaged hippie or a fascist in democrat's clothing."

Students generally express approval. "There was the smell of Mace [spray used by guards to break up rowdiness] in the halls last year but that's changed," said one student.

Except for a brief flare-up last year, tensions between blacks, who make up 30 percent of the student body, and the rest of the school appear to be low. Many blacks were angered over an article in the school yearbook last February quoting a coach as saying that "blacks are not as disciplined as they could be and they don't respect authority as much as they should." Some blacks picketed the newspaper office but prevailing attitudes may have been expressed by a young black woman who said, "That didn't really concern me."

Ober contends that the success of a high school as large as Evanston rests on continuing the extensive extracurricular program. In his view, these programs are not "frills."

"The whole extracurricular life is essential," he says. "Student government, dances, working as volunteers in the community . . . young people have to have a chance for service, a chance to play on teams, to put on plays, to be part of an orchestra that plays well, that shows them they have membership in a community where people are doing things for one another. This is how they learn something about following and leading, about respect for one another. This is how they learn to measure their own talents, to decide what is a good performance and what is a poor performance, what is a just act and what is an unjust act, what is a beautiful thing and what is an ugly thing. In other words, standards. We recognize that school is a character-forming institution and provides activities that are going to help them find a sense of values . . . partly through the curriculum, but much more through extra-curricular activities."

About 80 students are participating this year in Evanston High's "senior seminar" that substitutes for senior year. The program requires abstinence from drugs, alcohol and cigarettes. Participants spend weeks on a farm, in downtown Chicago, on jobs and back at the school writing and putting on an original play.

Oddly, perhaps, programs such as these have been questioned around the nation by parents demanding a return to "basics" and by school boards bent on budget cutting.

In Ober's view there is no trading off extracurricular for curricular programs. But many school systems around America do not see it this way. Sports, extracurricular and innovative programs have been the first to go in economy campaigns.

"During cutbacks and retrenchment, the educational organization that will suffer most will be the high school because it depends on courses that are less obviously "cost effective than your basic elementary school reading and arithmetic courses," says Daniel Duke of Stanford University's school of education.

If these cutbacks continue, then even successful high schools will be hard-pressed to serve their youth, and Conant's preference for large, comprehensive schools could come under even more intense attack.

Scott Thomson, who represents U.S. high school principals in Washington, is one who feels that finding the right size for a school is important.

"When I was at Evanston one third of the boys were in interscholastic sports. But it's like shoveling sand against the tide. The large, comprehensive high school made sense when you had a very stable family and neighborhood situation, when kids were known in church and in the community, when a boy was known as the kid with a good sense of humor who's good in physics. Today we have a different neighborhood and family context . . . mobile families . . . kids not well known . . . maybe only a father or mother at home. Then a kid at a large school is just a number. He's a number in the community. And he's a number at school."