For most of the 3,200 students attending big, affluent, suburban North Central High, school this year meant going to class, joining a sorority, worrying about tests, thinking about college.

But for about 400 of North Central's students, it meant a chance to break away from that traditional routine.

Senior Vicki McBride spent an hour a week with a mentally retarded 8-year-old child, an experience that forced her to come to grips with her own feelings about sickness and suffering.

Shelley Herman, a junior who describes her reading skills as only average, negotiated a written "contract" with her English teacher to read 1,000 pages of literature in six weeks and had the contract witnessed by her parents.

For other students "school" meant working in last fall's state political campaigns, conducting a telephone interview with a top aide to Office of Management and Budget Director David A. Stockman, meeting at the home of a classmate to discuss religious differences between Jews and Christians, and taking a course from a school secretary with no formal teaching credentials.

These departures from traditional schooling were all part of this year's curriculum in Learning Unlimited, an alternative educational program that will go into its eighth year at North Central next September.

In many respects, programs such as these seem strangely out of place todlay in U.S. secondary education, which seems otherwise to be beating a hasty retreat from the innovation and change of the last two decades.

Alternative education was popular a few years ago. But many public schools, responding to parental concerns, are moving away from experiments tried in the 1960s and 1970s and back to more traditional methods.Budget cuts have dampened enthusiasm for bold new programs.

Educational "frills," ranging from dirver education to creative writing, are under attack by proponents of a "back-to-basics" approach to schooling. And influential spokesmen of the political New Right are attacking schools for exceeding their mandate in discussing sex, values and morals in the setting of the classroom.

Ironically, though, some educational reformers have never been more optimistic about the prospect for change. They maintain that programs such as Learning Unlimited contain just the ideas, techniques and concepts needed to revitalize the American public high school and save it from its increasingly vociferous critics.

These programs, say the reformers, can show the way to deal with teacher "burnout" and provide more options inside the public school system for concerned parents.

We view the trend [of public opinion] as a boon to alternative education," says Gary Phillips, a former juvenle probation officer who helped found Learning Unlimited. He now directs the national School Improvement Project, which receives funds from the Charles F. Kettering Foundation of Dayton and Eli Lilly Endowment of Indianapolis.

"Along with 'back-to-basics' there is concern for accountability, more examination of what schools do, and a search for alternatives," Phillips maintains.

"Since I got out of high school in 1957, schools have not changed very much," Phillips goes on. "But society has changed. We have kids who 'outknow' their teachers. We have kids getting information in other ways. Teachers tell me that students are more apathetic, that schools are less important to them, that there is less family support, that homes are more chaotic, that students have a different attitude to authority. But when I ask the teachers what they are doing differently, they say, 'not much.'"

Similar doubt about the adaptability of the American high school was expressed in a controversial study, called "Giving Youth a Better Chance," published in 1979 by the Carnegie Council on Policy Studies in Higher Educaiton. It recommended that large high schools be broken up into smaller units and proposed such radical changes as reducing classroom time to three days a week to allow more time for work experience and community activities.

In Phillips' view, educators misunderstand public opinion if they think most parents want shools to teach mastery of facts rather than deeper skills and attitudes that could last a lifetime.

He contends that the current interest in religious and private schools shows that parents want schools to be concerned with values and spiritual matters that go beyond book learning. And he is convinced that the public high school of the future will provide new opportunities for community and parental involvement.

Phillips says he has been given a mandate by Kettering and Lilly to "change the American high school" -- a monumental task that the predicts will take at least 10 years. At this stage he is directing several modest experiments, including one at a large, minority-dominated Indianapolis public high school. The next step, which will come in several years, will be to build a national network supporting extensive change, he says.

The Learning Unlimited experiement was one outgrowth of an effort in the early 1970s to improve the quality of educaion at North Central, an affluent school in suburgan Washington Township that even then ranked as one of the most successful high schools in the country.

Phillips and his faculty were given broad freedom to try new techniques that would attract not only potential dropouts but also the "silent majority" of successful by unchallenged students.

What has come out of this is a high school within a high school whose methods would shock many conventional teachers and administrators.

Students sit in on planning meetings with teachers, answer the telephones, or go off with a teacher for a "family group" meeting at a local fastfood shop. Others conduct "telelectures" -- telephone interviews. They have had writer Studs Terkel, the mayor of Indianapolis and Lillian Carter's Secret Service man on the line.

They have also grilled speakers representing the Moral Majority, the American Nazi Party and the Communist Party of the U.S.A. at "town meetings."

But the core of the program today is "individualized learning," a lofty concept that is brought down-to-earth by the requirement of student contracts. These contracts, which are negotiated with teachers, define the students' objectives for each course.

Students are expected to identify their own weak points and set up a challenge that can strengthen them. In line with Learning Unlimited's view that all kinds of personal development have a bearing on educational achievement, contracts often contain a component that is not directly academic, such as working with retarded children, learning how to change a tire or going on a "walkabout," or experience being away from home.

The contract system is meant to shift some educational responsibility from the school to the youngster -- to "transfer ownership of education to where it belongs," as Phillips puts it. But it is also intended to fit the challenge to the need of the student.

Phillips says he believes "ownership" should be extended to failure as well as success. At North Central he offered students with behavior problems an option of writing contracts in which they "chose to fail," as a means of forcing them to accept responsibility for their actions.

At the other extreme are highly gifted students, such as Jonathan Tanner, for whom the program has had benefits. A brilliant but somewhat shy student who was recently accepted by Harvard, Tanner contracted to take alternative gym because "I'm not really a great athlete . . . but in the alternative program you were rated on how hard you try rather than how good you are to begin with."

Tanner also signed up for a government class with Learning Unlimited teacher Bob Faris and set himself the goal of improving his ability to work in a group. With Faris's help Tanner became involved in several ambitious projects in which he worked with classmates on computers, and instructed the class on how redistricting was likely to work in Indiana based on his analysis of census data.

Over the years the program has had its share of criticism. In its early days, other North Central faculty members sometimes complained that Learning Unlimited teachers raided their classes looking for promising students. Faculty members acknowledge that the program also attracted more than its share of hippies and drug users in its early period.

Even today, Learning Unlimited students say, other North Central students sometimes joke that the program is for "freaks" and that it was less academically challenging than conventional school courses.

A senior quoted without identification recently in the student newspaper said of the program: "I cheated on tests, did no homework and received an 'A' for the semester . . . I majored in McDonald's."

But those familiar with the program take sharp issue.

"We tell the other kids how much fun we're having visiting coal mines or helping retarded kids and they say since you're having so much fun you must be cheatin' at something," was one student's answer to the criticism. "They don't understand it, so they knock it. I'm just as glad because otherwise they'd all want to be in."

Shelley Herman, now a junior, says students who criticize the program lack the self-motivation required to succeed in it. Herman says she was bored with school until she joined the program.

For others, Learning Unlimited seems to be providing a sanctuary from the impersonality and social pressures that are present at any big high school.

"I feel close and comfortable to people here," said a girl. "I come to them with my problems and I don't feel I'm imposing."

For teachers, Learning Unlimited has provided flexibility and freedom from bureaucracy. English teacher Mike Cupp says he was nearing "burnout" at a junior high school when he moved to Learning Unlimited. Now he says he stays friends with some of his students years after they graduate.

For parents, the appeal of the program is that it offers a different kind of educational experience for their children at the end of the same bus ride, rather than at a private school, or at some other high school.

On indication of the program's overall acceptance was the decision of the township to assume the costs of continuing the program after the Lilly Endowment funds ran out four years ago.

Jim Ellsberry, the assistant principal in charge of Learning Unlimited, acknowledges that evaluating the program is not simple. "We're dealing with outcomes that are difficult to measure," he says. "It's a lot easier when you're dealing just with Scholastic Achievement Test scores."

A 1976 study of grades and test scores attained by students in and out of the prgram found no significant difference.

More important in Ellsberry's view are tow other surveys.One in 1978 asked Learning Unlimted students and a control group from the regular school how they rated their high school experience in developing such attributes as appreciation of beauty, managing time, acquiring information, social relationships and ability to direct themselves. learning Unlimited students ranked their program higher to a significant extent.

A doctoral study conducted by Tom Gregory of Indiana University asked graduates of 20 Midwest high schools to outline what they thought an ideal secondary program should be and then compare it with their own experiences. The difference between ideal and reality was smallest in the sample of Learning Unlimited graduates.

Whether the experiences of an affluent suburban school can be transferred to the nation's deeply troubled big-city schools is another question.

However, Gary Phillips insists that he is developing a process and a concept that can be transferred, and already has been on a limited basis.

At George Washington High School an inner-city school attended mainly by minorities, 73 out of 88 teachers have volunteered to give up one free period a week to work on ways to "make the school a better place."

One experiment has involved bringing in five executives from the local General Motors plant as part-time teachers. Officials of the plant had complained about the caliber of youth hired locally.

But in their initial approaches to the students Phillips said, the executives ran into problems of their own. When they lectured the students about the importance of hard work they got a cold response.

Only when they changed their teaching tactic to give the students a chance to describe how they would set up their own business (a professional basketball team) did the class come alive with a discussion about hiring, the need for supporting services and loans.

Phillips cites this to illustrate his belief that schools can succeed if they work with the forces that influence youth rather than fight against them.