Oprah Winfrey, the professional talker, has announced plans to join the professoriate. This fall, she will teach at Northwestern University, offering a course on business and marketing strategy to students with a yen for careers in moneymaking. Winfrey is a certified draw -- a faculty lounge phrase for celebrity profs whose oversubscribed courses pack 'em in. It's not yet known whether she will read and evaluate student papers, or leave that irk to teaching assistants.

No doubt, the professing Winfrey before her students will be as entertaining as the witty Winfrey before her TV public. As a big-earning businesswoman, she has ample amounts of experiential tales to impart.

But a question. If Winfrey hankers for part-time teaching, why not head for classrooms where the need is sore and the challenges large: a low-income public high school or a prison? In those academic settings, real differences can be made and marginalized lives rescued. Hundreds of thousands of students pass through America's high schools every year without ever having one teacher who truly cared about them or made an extra effort to develop their hidden gifts. Our prisons are crammed with the ill-educated who never lucked out by having a caring teacher who might have intervened early enough.

Winfrey's students at Northwestern University likely already have it made or will be making it soon enough. Having a TV and movie star as their professor is another intellectual privilege in academic backgrounds packed with them.

Celebrity professors are common. After leaving the Senate and the ways of East Coast sophistry that he routinely scorned, Alan Simpson of Wyoming didn't go home to be among the cowpokes. The folksy yarn-spinner hired on to shape young minds at Harvard. Bill Bradley's post-Senate days found him far from the citizenry of New Jersey. He put in a few semesters at Notre Dame and Stanford. George Stephanopoulos took his show to Columbia. Then Bradley entertained for a semester at Georgetown.

I know of several Washington journalists who commute hundreds of miles to teach weekly courses at elite universities, while blocks from their newsrooms are impoverished District of Columbia high schools desperate for volunteer talent. Why not do part-time teaching there?

I have a hunch -- experience, not theory-based -- why not. Public high school teaching is the heavy lifting of American education. By comparison, college teaching, especially for wealthy part-timers who don't need the money and who are invited to teach an elective, is a summer breeze: no sweat, no strain. A student has a problem? See the TA after class.

At the center-city public high school where I began teaching a course on nonviolence in 1982, these words were recently posted on a classroom wall: "If a doctor, lawyer, or dentist had 25 people in the office at one time, all of whom had different needs, and some of whom didn't want to be there and were causing trouble, and the doctor, lawyer or dentist, without assistance, had to treat them all with professional excellence for nine months, then he might have some conception of the classroom teacher's job."

Imagine the morale boost that teachers at the nations 28,000 public high schools would enjoy if Winfrey taught a course in one of them. Or became a part-time teacher in the prisons where populations are rising and funds for education are falling. In the Maryland maximum security facility where I have been teaching juvenile offenders for the past year, my students have been a mix of felons, runaways, dropouts, the hostile, depressed, abandoned and the still-hopeful. Merely persuading them why they should work to be educated is as mighty a challenge as doing the actual teaching.

These aren't the breed of students -- the scrubbed and the sparkling -- crossing kempt acres at a $30,000-a-year university to be in a classroom before Professor Famous. Their educational needs run a bit deeper than picking up three credits for a weekly audience with The Awesome One.

Earl Shorris, a New York City writer, understood this immediately when he began teaching courses in the humanities and moral philosophy at the Bedford Hills Correctional Facility, a women's prison 50 miles north of Manhattan.

In "New American Blues: A Journey Through Poverty to Democracy," Shorris found students who had been caged directly off the streets but who were still reachable and teachable. They discovered that the study of art, literature, poetry and philosophy created a chance for empowerment.

"Unfortunately," Shorris writes, "we have been so conditioned to understanding the humanities as the province of the rich that the idea of teaching the humanities to the poor seems preposterous, a prisoner's fantasy, a joke told by Aristophanes."

When Shorris expanded the course to a Latino neighborhood in New York City, 31 students between ages 17 and 33 enrolled. Two-thirds were women, all were financially poor and all would be studying literature found in freshman liberal arts courses at Ivy League schools. Seventeen finished the course, and 14 earned six credits from the affiliated Bard College. During the course, Shorris told his students: "Rich people learn the humanities in private schools and expensive universities. And that's one of the ways in which they learn the political life. At every level. I think that is the real difference between the Haves and the Have-Nots in this country. If you want real power, legitimate power, the kind that comes from the people and belongs to the people, you must understand politics; the humanities will help . . . It is generally accepted in America that the liberal arts and the humanities in particular belong to the elite. I think you're the elite."

This was the thinking of another teacher who embraced an alien world -- Deborah Pugh, who conducted a twice-weekly, two-hour class on writing at Rachael's Women's Center in Washington. In "I Have Arrived Before My Words: Autobiographical Writings of Homeless Women," she states: "My new students thought [the course] referred to improving their handwriting or perhaps letter-writing. Writing about one's own life -- my purpose for the class -- seemed to many of them a dull and fruitless endeavor. Self-expression, writing about my life, making up poems -- what was that all about?" It turned out to be worthy enough to be published.

Initially, Shorris and Pugh found themselves among skeptical, wary students. It was that way, and more, the first day of class for Herbert Kohl, who has taught every grade from kindergarten to graduate school, in wealthy and impoverished schools. In "The Discipline of Hope," he recalls his first experience in an inner-city school in New York: "As I walked into the room one of the students jumped up and called me almost every name imaginable about being white and an oppressor and told me to get the hell out of his classroom. I had heard such words before and knew they had nothing to do with me; he didn't know a thing about me. I figured he might be a leader, so it would be good to win him over. He looked at the other students while he was carrying on, so I guessed that his confrontation was more theatrical than a matter of out-of-control rage."

Kohl defused the tension by focusing the student's and his classmates' attention elsewhere: He took from his pocket a barnacle he had gotten off the body of a dead whale at a beach he had visited a few days before. The class "took off on a discussion of whales. We had set off from New York and traveled beyond racism and anger into the curious and wonderful things the world has to teach when the students' minds reach out beyond their wounds and rage.

"That is the very source of hope -- that we can create places where young people can dare to dream without being brought down by the realities of their terrible experiences in schools and by an adult world that dares them to succeed rather than welcoming their energy, love, and contributions."

High schools are hot copy these days. If Professor Winfrey, retired senators or White House stars want a stiffer challenge than giving their time to students who already have received much, head for a high school, prison or homeless shelter. And when mental and emotional exhaustion comes, no feeling will be like it. It's called being alive, fully.