Carla M. Yock grew up in a rural Minnesota town of 973 where her father headed the school committee, was a member of the Chamber of Commerce, worked in the band boosters and had a hand in just about everything else.

"I guess I believe in community service," she said.

To her own activities, which already include work for the PTA, the American Association of University Women, the Republican Party, the school bond referendum committee and her church, she will add one more: Fairfax County School Board member.

Yock, 46, will take over July 1 for James W. Kitchin, 57, as the School Board representative from the Mason District.

Supervisor Thomas M. Davis III praised Kitchin's service, but said the demands of his job did not allow him enough time for school duties. The Board of Supervisors voted June 17 to accept his recommendation to replace Kitchin with Yock.

Yock was a contender for the School Board four years ago, but a selection committee named by Davis recommended Kitchin instead.

She has lived in Fairfax County for 16 years and taught in the county for seven, all at Glasgow Intermediate School. She will resign her job teaching civics and history to avoid conflicts of interest when she joins the School Board. "I'm going to miss the kids," she said.

In a recent interview, she had unstinting praise for the county schools, calling them "super terrific" and a good place to teach. But she acknowledges that ethnic diversity, school boundary changes and a new high school in the Mason District could create problems she has to watch.

She knows firsthand about the thousands of foreign-born families that have come to Fairfax County. Last year, she taught in one class alone three students whose native language was Spanish, two speakers of Urdu, one Cambodian and a Vietnamese. "They don't know the obvious -- like that George Washington was the first president of this country," she said. "It's fun."

In some schools in her district, a majority of the children are from families for whom English is not the first language. Some American-born parents, resentful because they believe English-speaking students do not get needed attention because of the demands of the foreign-born, have pulled their children out of county schools.

"We have to win the confidence of some parents who are looking at alternatives," Supervisor Davis said.

"We must meet the needs of all kids. And I want to emphasize that -- all kids," Yock said. "Any problems that there are, if there are problems, are not insurmountable." And she added: "The diversity adds enrichment to the educational experience."

Another issue Yock said she will watch is the merger of Jefferson and Annandale high schools. Jefferson, located on Braddock Road in Annandale, will become a magnet school for students interested in science and math. It will be phased out as a regular high school by 1987, with next year's freshmen attending Annandale.

Yock said Jefferson will have special staffing needs as the enrollment changes. School officials have promised full staffing for the regular students "and I expect them to honor that commitment," Yock said.

One of her daughters will be a senior at Jefferson next year."I know about the emotional involvement" of closing a school, Yock said.

Her other daughter will be a freshman at the new Thomas Jefferson High School for Science and Technology, the first school of its kind in Northern Virginia. "It's a new concept for Fairfax County," Yock said. "So far, it seems to be shaping up beautifully."

Yock cited parent concerns that students should have a range of activities -- music, fine arts and athletics, in addition to science and math -- and that they should have proper transportation. She said she will monitor both issues.

Yock is a former branch vice president and legislative lobbyist for the American Association of University Women. She lobbied in Congress and Richmond on such issues as family violence, campaign reform and foreign aid.

She also worked for the Equal Rights Amendment in anti-ERA Richmond ("That was an educational experience," she said) and served on a county committee that assessed sex bias in the schools in the late 1970s. Changes were made as a result, and Yock now believes the schools treat boys and girls equally.