Fairfax County's concerts-in-the-schools program for elementary and intermediate grades has reached more than four times as many students than it did this time last year, according to volunteer parents who support the art effort.

Only about 24,000 children were involved in the program last season, said Sue Kraft, who schedules concerts for the entire county. She said current projections indicate that more than 100,000 students in 46 schools will see one of the 83 performances in 1977-78.

"This time last year," Kraft said, "we had only 10 or 12 concerts planned for our school children for January."

This dramatic increase in the number fo concerts scheduled in the school system has given unexpected new life to a floundering program, she said.

"We were thinking of dropping the entire program if the number of schools booking concerts hadn't increased," she said.

The concerts are not funded by outside sources. The artists are paid from either school funds or money raised by PTA groups. The charge ranges between $30 and $285, depending on the number of performances given at a school and other factors. A fee of $10 is deducted by the Fairfax County Council of the Arts (FCCA), primarily to cover admistrative and maintenance costs. The school concerts pogram has been available for seven years under the aegis of the FCCA, a private, nonprofit arts coordinating agency.

"We're not really looking for funding, though. We're a volunteer booking agency and plan to keep it that way," Kraft said.

FCCA's Peggy Amsterdam says that the burgeoning number of concerts booked this year "is the result of the work of Susan Kraft. We had our usual evaluation meeting last year and Sue suggested a couple of things.

"First, she asked that we expand the volunteer concert committee and second, that we put together a really professional brochure on the program and get it to the principals, teachers and PTA's before the school year started," Amsterdam said.

Another new project this year was the first "Performers' Showcase" held recently in the Robinson High School auditorium. The event, Amsterdam said, was designed to present sample performances by individual and group artists working in the schools.

A total of 400 teachers, principals and PTA representatives were invited, especially those from schools that had never used concert performers. Kraft estimated that "about 70 persons showed up" and said that she was pleased with the turnout.

William Martin, principal of Sherwood Elementary School, attended the presentation. "It was really a good demonstration of artists," he said. Part of his concert fund comes from PTA cultural committees and /art from "picture money - we earn some money each year on th e photographs we have taken of the kids."

Martin said that he books at least two to three programs each year and doubts that other schools had that many.

"There's just not enough money to do what you'd want to do," Martin said.

Kraft estimated that as a concerned parent she donates an average of 12 hours each week to arranging performances and coordinating the concert schedules throughout the school year. The 20-member concert-in-the-schools committee also volunteers many hours of service to program, she said.

"I believe the Performers' Showcase was the final clincher in raising our concert projections for 1977-78," Kraft said. "In future years, we plan to do it even earlier in the school year."