THEODORE SIZER stands in his small orderly office at Brown University, talking on the telephone to a harried school principal. He's got to ring off soon, but he's not about to rush her, because she's got problems, and her problems are his problems. Shifting from one foot to the other, and occasionally tugging at his tie, he doles out a stream of sympathy, reassurance, suggestions and humor, telling her to let him know how things go, even to call him at home.

The principal, in an urban high school, is one of 46 around the country who are trying, with Sizer's guidance, to revolutionize American secondary education. As members of the Coalition of Essential Schools, an umbrella organization headed by Sizer at Brown, where Sizer is education department chairman, they are implementing radical changes in the organization of schools. And as all of them can tell you, it may be exciting to start a revolution, but it isn't easy to sustain one.

Sizer's approach to high school, laid out in his book Horace's Compromise (1984), is to strip education down to its essentials -- literacy, numeracy, the ability to think and reason. The ideal Sizer high school would have students work in small classes of no more than about 20, with teachers who act as guides rather than as authority figures, making students do the work of learning by constant questioning, exploring ideas, and, importantly, writing, writing, writing. The ideal Sizer student will learn how to learn. He may not have memorized every element of zoological classification but if asked to define orthoptera, he will know how to go about the task.

Sizer has spent his lifetime teaching young people or guiding those who would teach them, first at Roxbury Latin School near Boston, later as the dean of the education faculty at Harvard (1964-72), and now as head of Brown's education department. But, he says, "Most of my theories and ideas about education came to me in the '70s, when I was headmaster of {Phillips Academy} Andover. All these studies started coming in. There was a lot of pessimism. There was an awful lot of attention paid to the Coleman Report and its offspring with their messages that 'schools don't make a difference -- tell me your income and I'll tell you your SAT scores,' that kind of thing. There was another study about literacy in the Third World. And they all seemed to talk about cohorts of kids. The impersonality of it all nagged at me. They talked about 14-year-olds as if they were all alike."

While Coleman and others were saying schools didn't make a difference, Sizer said he was looking at Andover, which with its large endowment supports many scholarship students, and it was making a difference.

"About the same time I started having regular meetings with other school heads. We'd sit there and puzzle over public education. Why was everything going bad out there? What was happening?"

Sizer decided to find out for himself. With funding from the Commonwealth Fund and five other foundations, and joint sponsorship from the National Association of Secondary School Principals and the National Association of Independent Schools, he assembled a staff of observers and began the five-year project known as A Study of High Schools. The project turned into an odyssey that took him and others to more than 100 high schools around the country. Horace's Compromise was the result of the study.

The book is a scathing indictment of American secondary education. The average comprehensive American high school, Sizer argues, is like a shopping mall offering a vast array of wares. Too many students are left to drift through the diversity, and for lots of them the school is little more than an elaborate baby-sitting service.

Sizer's criticisms and his call for improved American education came on the heels of two other reports, "A Nation At Risk"(1983) and The Carnegie Endowment Report on High Schools (1983). Not since the Russians launched Sputnik in 1957 had there been such a hue and cry for improvements in American education.

However, the political response, which continues still, has not been to adopt Sizer's plan for smaller classes and fewer subjects but rather to impose more requirements, more regulations, more competency tests, in some cases more days in school.

Sizer acknowleges that he's been swimming against the current. "But the current is easing," he says. "Improvements {brought about by state regulations} have so far been so slight that they are virtually meaningless."

And according to Holly Houston, executive officer of the Coalition, more and more schools are inquiring about the Sizer reforms. Her office receives about 10 written inquiries each week, and countless others by phone.

Teachers are the Key

THE KEY to any improvement in education, according to Sizer, is the teacher. In an Essential School, the teacher's role is drastically different. In addition to being responsible for about 80 students, instead of the standard 150 many public high school teachers face in a single day, teachers are expected to act as mentors and guides through academic material. The Coalition stresses a personal relationship between teacher and student.

Teachers work in teams. They, not administrative curriculum specialists, decide what they will teach, based on the needs of the class.

Michael Goldman, a teacher for 14 years in Manhattan, developed a social studies program for 7th and 8th graders at Central Park East Secondary School, which last year studied the American and French revolutions in tandem.

"At the beginning of the year, I told them, 'Here's what we want you to do: compare the French and American revolutions; debate the merits of both sides of each revolution; and finally, know the chronology and the geography of the American revolution."

"You'd be surprised, some of the kids came to the conclusion that the Americans had been wrong," added Goldman.

Now Goldman is busy devising a curriculum on immigration, to be used next year.

At Paschal High School in Fort Worth, Texas, English teacher Jhani Williams had her 10th graders study The Iliad last fall. The conclusion of the project was a paper on the poem and, according to Williams, the students wrote and rewrote their compositions five times. In a conventional class, there would have been time to rewrite papers only once, she said.

As befits a champion of good teaching, Sizer himself has never lost touch with the art. Even as Andover's headmaster, he taught an American history course. And now, at Brown, he teaches an immensely popular course called, "Going to High School in America: 1930 to the Present."

Three hundred students signed up for the course in 1985-86. Sizer, who believes firmly in class discussion and the Socratic method, found himself teaching with a microphone in an auditorium, the only place big enough to hold everyone. The course is now limited to 150 students -- still too large in Sizer's view.

Sizer's own teaching talents have also been credited with doubling the number of Brown undergraduates majoring in education since he came there in 1984.

'Worth Every Penny'

THE Coalition of Essential Schools is a loose organization. Being anti-bureaucratic, Sizer has insisted on keeping a small staff of six. They answer inquiries and oversee the Coalition's business from offices in the rear of Brown's campus police station.

At present the Coalition consists of 46 schools, both public and private, including 11 who signed on when the project began in 1984. More are being added gradually -- six in the past year. In order to join, a school must make the first overture. Then follows a kind of courtship period when Sizer, Houston, or other staff members visit the school, talk with teachers and determine how serious the intention is. If there is enough enthusiasm on both sides, a formal agreement is signed with the local school board, pledging support for the program for at least four years.

This procedure is "more formal" than it once was, according to Houston, partly to ensure that even if principals and school boards change, the Coalition school will have some continuity in the community.

Sizer has his critics, who point to the absence of universal standards against which to measure how well Essential Schools are preparing their students. Also the schools are relatively expensive to operate, which can spell local political trouble for them. Sizer estimates that running one will cost 10 percent more per year than a conventional high school. Others disagree.

"It simply cannot be done with a 10 percent cost override," said Larry Barnes who administers the essential school program at Paschal High School in Fort Worth. "But you can do it with 15 percent more. It's an expensive program, but it's worth every penny." Barnes said Paschal manages because of a generous sustaining grant (he declined to say for how much) from the Tandy Foundation.

Sizer's staff came up with the 10 percent override figure after studying the $3 million budget of an actual high school.

"You can have smaller teacher/student ratios, but you can't do it and have all that a comprehensive school has," said Sue Follett, an economist who worked on budget projections. To finance a lower teacher/student ratio, trims must come off the top, Follett said. Resources must be rearranged with the result that there are fewer administrators and guidance counselors and smaller athletic budgets (with parent boosters making up the cash difference).

Teacher Power

AS HIS ideas gain favor, Sizer is finding himself more and more in the eye of political storms. Both liberals and conservatives claim him as an ally in various causes, and both teacher unions, the American Federation of Teachers and the National Education Association -- known to disagree on occasion -- support his views on the importance of teachers.

This clearly worries Sizer a bit.

"Empowering teachers is the new fashion," he says. And since one of the cornerstones of the Essential School is giving teachers more autonomy, Sizer is naturally thought to favor the movement.

"But," he demurs, "Empowering teachers doesn't interest me. What is important is helping kids learn better."

Another issue that Sizer supports, a favorite among educational conservatives, is that of parental choice. Sizer points to New York City's District 4, in East Harlem as a promising development. There parents may choose among schools with a variety of programs -- a fine idea, according to Sizer. He would let the market determine which schools survive and which ones fail.

"Most of the private schools begun in the 19th century went under or were absorbed," he says. "The reason? They didn't serve their constituency. If they didn't, they died."

Now, says Sizer, hundreds of moribund schools are living on, supported by public funding. Better to let them die.

There are schools from all kinds of communities in the Coalition, but according to Sizer they are "probably disproportionately skewed to lower income groups."

"The program is particularly attractive to teachers who know they've got to do something radical to reach students," he says. "It's harder to change the status quo if the status quo is getting kids into Yale."

The Coalition of Essential Schools, as it's currently structured, is due to conclude its business in 1994. By then, essential schools will have produced scores of graduates. (Since most began their programs with 9th graders, there have been none so far. The first graduates receive their diplomas next spring.) And the schools themselves will have been the subjects of study and scrutiny and perhaps even more books. Sizer looks a little wistful when he contemplates 1994.

What does he hope will have been accomplished?

"The first step is to show it works," he says slowly. "Then I predict that seven years from now, you will be able to demonstrate that essential school students will out perform a matched sample of students from ordinary schools -- and by matched I mean matched by socio-economic grouping -- on any rational test.

"Next, I think we'll see that our graduates are more thoughtful. They'll be better able to see the consequences of actions.

"And finally, I hope that the schools that produce these kids will be stable. For that I will be grateful."

Alice Digilio is the editor of The Education Review and managing editor of Book World.