At 60, Doris Broome Deboe still spends 10 to 11 hours a day teaching, tutoring or preparing for her math classes at Washington's Banneker High School, and that does not include the time she puts in on weekends.

She is available to help students before classes begin, after they end, and through her lunch period. In 1983 Deboe was one of about 100 math and science teachers around the country selected for the Presidential Award for Excellence in Science and Math Teaching.

"I teach because I love the job," she says. "Sometimes, I don't get out of school before 4:30 p.m.," more than an hour after the school day ends.

She is an example of the kind of teacher every interested parent would want for a child's education. Unfortunately, she is also an example of the kind of quality in the classroom that may be difficult to find in the very near future. It will be difficult because she represents the aging generations of fine black and female minds who chose teaching in the '40s, '50s and early '60s and are now in the twilight of their careers. They chose teaching, in part, because so many other doors of opportunity were closed to them. But they also chose it because teaching then carried a prestige, a sense of responsibility that has paled in relation to other professions as more and more talented blacks and women gained footholds in higher-paying and more upwardly mobile jobs.

In the District's public schools, more than 60 percent of 5,700 teachers have already taught for 15 or more years and will begin reaching the retirement age in the next five to 10 years. In Maryland, the state's education department predicts a shortage of 6,000 teachers before the end of the decade.

And who will fill those shoes? Few of the country's best and brightest. Many fear that most of those who will turn to teaching will do so because they do not have the talent to land more lucrative jobs.

In a national survey of 1,000 teen- age students last year, fewer than 6 percent expressed an interest in teaching as a career. One of the students surveyed was Jill Neptune, a talented young woman from Shawnee Mission, Kan. Her mother was a math teacher, but Neptune had her sights on a career in business -- and not only because of the higher salaries she could earn.

"You have a chance for promotions and to go somewhere. In teaching, the opportunity for advancement is not there," she said. "You are a teacher, and you seem to be stuck in that mold."

When Doris Deboe finds a talented math student, she will suggest a career in teaching. Few are interested. Her three daughters saw the long hours she put into her teaching, and only one tried the profession. That daughter lost her teaching job in her first year, during a financial crisis in the D.C. schoos, and never went back. Another daughter has worked for the International Monetary Fund for just a few years and already earns more money than her mother, who has taught since 1949.

But simply raising salaries is not enough. Veteran teachers talk about something more fundamental: a decline in respect for the profession, less disciplined students, an image of teaching as a job one gets stuck with if other opportunities fall apart.

"To be a teacher was an honor," said James Williams, now the principal of Cardozo High School. "Everyone looked up to you. Respect was there immediately. You could get credit to buy things just by saying you were a teacher. Those times have changed."

Even Deboe says that she would not go into teaching now if she were graduating from college. She suffered a serious illness a year ago and could have retired. She dismissed the idea of retirement again this year. The reason? The troubling thought of seeing someone with no love or enthusiasm for teaching at her desk.

"I am afraid of who is going to replace me," she said. "That's why I'm still sitting here."