Vandalism at Fairfax County schools totaled $382,818 last year, a $50,384 or 15.2 percent increase over fiscal 1977, according to the county's Office of Support Services.

"The increase for the most part is inflation," said Barry Morris, associate superintendent of schools. "The cost of repairing damage has escalated, so it's not all due to increased vandalism."

Raymond McGuire, the schools' officer of management and planning, said the most expensive type of vandalism occurs during the daytime in high schools when students break and steal valuable laboratory equipment, lockers and bathroom fixtures.

Vandalism at night and on weekends, he said, consists mainly of breaking windows. Last year Fairfax County schools spent $91,850 repairing glass broken by vandals.

Under Virginia law, parents of school vandals who are caught and convicted may pay up to $200 in restitution. In fiscal year 1977 parents paid the schools $7,000 in restitution.

Toni M. Carney, school board representative from the Springfield district, said schools have had success with two methods of curbing vandalism.

"The most effective method has been the 'lights out' program," said Carney. "We started it to save energy by turning out all school lights at night and found a substantial decrease in vandalism in these schools."

Carney said she thinks youngsters don't find dark schools "such attractive nuisances." She said more schools will be keeping their lights off this fall.

Morris said schools also have been trying to instill pride in students and the community, so students will no longer "turn away when somebody else does damage."

Morris also said security patrols, added because of school vandalism, have been more visible in the daytime.

At the board's July 27 meeting, school board members recommended that the administration study vandalism and find additional methods of controlling it.

In other business, the board voted unanimously to require high school students graduating after 1981 to complete 15 required courses out of the 18 needed to graduate. Currently students must complete 11 required courses.

Freshmen beginning this fall must complete two courses in math; two in science, including one lab science; four social studies courses, and one fine or practical arts course. Students have been required to take only one math and science unit. English requirements will remain at four units, and health and physical education requirements remain at two.

The board said these changes were being made in order to better prepare students for college. Board member Ann Khn (Providence District) said, "Our concern is that (math and science) are certain areas where it is critically important for a youngster coming out of high school to be better prepared. This is a recognition of the kind of world these youngsters are going to be in when they graduate."

Voted to end the delay in the planned demolition of the 52-year-old wing of Chesterbrook Elementary School on Kirby Road in McLean. Further delay, the board said, could result in a lawsuit by the contractor.

A group of McLean parents had tried to halt the destruction of the wing because of its historical value. A new gym will be built in its place.

Vice Chairman Anthony T. Lane recommended that the board approve a $70,000 to $73,000 loan to Fairfax high schools in order to buy safer football helmets. Lane said the helmets, which cost $40 a piece, have been recommended for use by the National Council on Safety Equipment.

"Seventy thousand dollars is nothing if it could help save a life," he said. Under his proposal, schools would have until 1980 to repay the loans. On Monday the board, meeting in a special session, approved a loan of $75,400 for the helmets.

Increased non-resident tuition to $1,990 for secondary school students and $1,775 for intermediate schools - an increase of $120 for each. Elementary school tuition was raised to $1,640, a $110 increase, and kindergarten was increased by $55 to $820.

Announced the retirement of associate superintendent for school operations, Barry Morris, after 16 years in the Fairfax school system. He will be replaced by Jacqueline S. Benson, who is now assistant superintendent for instructional services.