They have no children in school. They seldom attend school board meetings. They no longer go to parent-teacher meetings.

But they are the people who could have the greatest influence on the direction of the Fairfax County Public Schools this year: the residents of the older sections of the county inside the Beltway, the parents who put their children through school a generation ago.

This year, the school board and county Board of Supervisors will ask those residents to help approve a $57.2 million bond referendum, most of which will benefit residents on the opposite ends of the county.

The school board is faced not only with selling the need for the bond referendum, but with convincing voters who have no vested interest in the issue to support it, according to board member Gerald Fill, who represents the older Mount Vernon area of Fairfax.

Most of the money will be used to finance new school construction in the rapidly growing western and southern sections of the county, where the burgeoning student population is outgrowing existing facilities.

In an attempt to make the referendum slightly more palatable to voters in the older sections of the county, funds have been set aside for renovations to some schools in those areas.

So far, the board has done little to publicize the referendum. When the members return from their August recess in September, they will have less than two months to package and sell the referendum before the Nov. 3 election date.

On other financial issues, school officials are anticipating cutbacks in some areas to absorb the costs of programs previously financed by the federal government. The pinch already is being felt in areas ranging from school lunch prices to special education.

One budget area may put the school system in a standoff with Uncle Sam, some school officials are predicting. The board is waiting to hear the budget fate of the federal government's $4.4 million in impact aid money used to offset the cost of educating the 1,520 children of military personnel assigned to Fort Belvoir.

Students at eight of the county's 23 high schools will find a new curriculum offered in their class schedules: a liberalized sex education course that will allow discussion of the previously banned issues of contraception, abortion, masturbation, homosexuality and rape.

The revised curriculum is part of a pilot course this year, which comes after five years of bitter debate over what had been considered the area's most restrictive sex education program.

At the end of the year, the program will be evaluated and the board could face yet another battle: whether to extend the program to the intermediate school level.

Meanwhile, Superintendent Linton Deck will be giving his new management plan a trial run. The plan includes proposals for a Saturday fine arts program, special high school programs for gifted and talented students and a computerized school library network. Many of the proposals are only in the developmental stages and won't find their way into the classrooms unless the school board decides, in budget sessions next spring, to provide funds for the proposals.