Spurred by one mother's impassioned statement, a community school board meeting in Northwest Washington Tuesday night developed into a lively debate over a little-noticed phenomenon -- the growing number of middle-class black parents moving their children from public to private schools.

"I am committed to the idea of public schools," said Judith Winston, a mother of two who lives in the middle-class, mostly black, Ward 4 area of the city around upper 1lth Street.

"And I am pleased with the education my children can get at Shepherd [the local elementary school]," she said. "But I feel that the junior high school in the Shepherd area is chaotic and it is not effectively reorganizing its programs to stem the tide of children going to private school in the Shepherd area.

"My own decision," said Winston, "was that I no longer had either the time or the energy to devote to improving the school... I don't have the confidence to say to my child, 'you can go to Paul [the local junior high school] and learn and grow because other children have done it.'"

Over the past few years the number of black District children attending private schools has remained fairly constant while the number of children in public schools has plummeted by more than 10 percent. Thus the proportion of black students in private schools in the city has increased.

Statistics on the number of city students enrolled in private schools for the 1978-1979 school year have not been released yet by the District's State Office of Education but school officials acknowledge that the loss of students from middle-income families with good home lives is a major threat to the school system at a time when it is trying to rejuvenate itself.

"We're losing the cream of the crop," said a school board member who asked not to be identified -- one of six board members to attend the meeting at West Elementary School in the 1300 block of Farragut Street NW. "And we're losing them just when we can see the light," the board member added.

After Winston spoke, board member Barbara Lett Simmons said the shift of middle-class black parents from the city's public schools to private schools "smacks of racism and classism... And if it continues we will wipe out a generation of the 20th century b creating a [public] subschool system."

"It hurts me to hear that only poor people are keeping their children in public schools," said Simmons.

Winston, who was still sitting at the speakers' table while Simmons spoke, answered her by insisting that she and other middle-class parents want to keep their children in the public schools, but don't feel it would be fair to the children to leave them in public junior and senior high schools now.

"We want to be wanted," said Winston to the six school board members, the superintendent and about a hundred persons who attended the community school board meeting. "It is up to the school system. If the school system wants us to stay in the public schools then they are going to have to demonstrate to our children and to us that something is being done to improve the schools."

A white parent in the audience stood up and complained that too often teachers in the junior high schools tell parents a student is "doing fine," without closely examining what the child has learned or should have learned.

Winston turned to this parent and told him that the school system's new Competency Based Curriculum, which sets out learning objectives for students in each grade, should prevent teachers from giving such vague responses to inquiring parents who what to know how their children are doing.

Then Superintendent Vincent Reed asked for the microphone to tell Winston and other parents who had raised the same issue: "I know your problem and it is something we are working on."

After the meeting, Winston, a lawyer for the U.S. Department of of Health, Education and Welfare, said she sent her 12-year-old daughter, Lisa, to the National Cathedral School for Girls last September after the child had graduated from Shepherd. Winston said she also intends to send her other daughter, now a third-grader at Shepherd, to private school.

Philippa Jackson, executive director of The Black Student Fund, an organization that helps to get black public schools students into private schools in the Washington area, said an increasing number of black parents of D.C. school children are contacting her agency.

"The calls we are getting are really increasing very rapidly now," said Jackson, noting that two years ago she received about 350 calls from parents and last year about 1,000 calls.

"For some reason," Jackson said, "parents feel that public schools in Washington are not meeting their needs. The child isn't rewarded for being a good student and after awhile they begin to lose interest in academics, particularly in the upper grades."

Jackson said her agency has a net-work of contacts among school counselors and teachers in Washington schools that finds bright students who would thrive in private schools instead of becoming bored in D.C.'s public schools.

School officials are also concerned about the number of black middle-class families that are moving to the suburbs to allow their children to attend suburban public schools.