Camilla McKinney, sitting alone in a Ballou High School classsroom, shrouded in books during her lunch period, doesn't look like the kind of student who often leaves the Southeast school in a chauffeur-driven sedan.

The car takes her downtown to work. McKinney, 17, is the lone student representative on the D.C. Board of Education. Her constituents are the school system's 87,000 students.

McKinney, a serious and forthright girl, is on the board to present student views. When McKinney, who often consults with student government leaders, speaks, adult members of the board usually listen closely.

"There's a tendency for board members to see themselves in the role of teachers" when talking to McKinney, said board member Edna Frazier-Cromwell. "But I think it's a dual role. Hopefully, she will learn from me and I will learn from her. She brings the kind of commitment and enthusiasm that's needed. I hope she can keep it as she runs up against obstacles."

As the board's student representative, McKinney can serve on committees and vote as a committee member. But she has no vote at meetings of the entire board. In spite of this restriction, McKinney says she has enough political power to make a difference on behalf of her constituents.

"Power is the ability to make changes," she said. "I want to use power to get the students' voice heard by the board."

For McKinney, the number of hours she puts in as student representative varies from "sometimes zero hours a week, sometimes eight-day weeks," she said. She attends fewer than 10 meetings a month and receives $50 a meeting.

McKinney, an honors student in Ballou's rigorous math and science program, is best known as a "very mature young lady," according to observers.

"She rarely smiles. She's very serious and does extremely well on standardized tests," said Emily Washington, a humanities instructor at Ballou and director of the citywide humanities program. "But what strikes me most about Camilla is her self-discipline. She believes that there isn't anything that she cannot do."

McKinney was elected to the school board last May by members of the citywide student government council, a body of student leaders. Her campaign slogan was typical of her quiet determination: "If Anyone Can, McKinney Can. . . . I can and I will."

Her scores on the Preliminary Scholastic Aptitude Test last year were high enough to qualify her as semifinalist in the National Achievement Scholar competition, and could result in scholarships to pay her way through one of the Ivy League colleges she wants to attend.

McKinney was reared by her grandmother, a retired nurse, in upper Northwest Washington, where she still lives. Her mother, who is unemployed, and her father, a civil engineer in the federal government, separated when she was a child, she said.

McKinney aspires to be a lawyer and a politician. She enjoys listening to soul, rock and classical music, watching movies and reading. She never sought elective office before running last year to be the board's student representative.

She ran for the school board, she said, because "it's an excellent opportunity to find out how politics works and have a chance to speak in public as lawyers do.

"Students are concerned about the student representative gaining the right to vote on the School Board," she said. "They are also concerned about attendance, the grading system of teachers, supplies and equipment and outdated books, as well as the physical conditions of buildings." McKinney now believes that it is unlikely that students will gain a vote on the board, and prefers to concentrate on more " realistic goals.

She is lobbying board members to amend a proposal that would prohibit students from leaving school grounds during lunchtime. McKinney believes high school students should be exempt because "on the high school level, students have the maturity to regulate their hours and attend classes as they should," she said.

After several high school students took a similar position at a school board meeting last month, several board members and superintendent Floretta McKenzie indicated that they would reconsider the "closed campus" proposal -- intended to curb juvenile delinquency.

McKinney favors another board proposal that would require students involved in extracurricular activities to maintain C averages. Students at the community meeting supported her position. "If you expect more from an individual, then he will give you more. Students can handle the 2.0 average requirement," McKinney said.

McKinney is reluctant to criticize the school system. Last summer, she said, a counselor told her that her application for a prestigous Massachusetts Institute of Technology MIT program for high school students "got lost in the school mail system."

"The counselor who had the application is a very good counselor, she just made that one little mistake," McKinney said. "I just did something else." She worked in a research lab at Georgetown University. Recently, the PSAT scores for 127 Ballou students were invalidated because teachers had allowed students too much time to complete answers.

While others have said that the mistakes were due to "carelessness," McKinney has refused to join the critics.

Like any good politician, McKinney helps her constituents. Laurette Dickerson, 15, an honors sophomore at Cardozo High School, said, "Students know that if they have a problem, Camilla will put forth her best effort to solve the problem."