Fairfax County students will return next week to a school system that offers new facilities, new administrators and renewed community understanding and cooperation in the wake of several school closings.

Highlighting the 1985-86 school year is the new Thomas Jefferson High School for Science and Technology in Annandale, one of four such schools in Virginia designated by Gov. Charles S. Robb as specialized "magnet" facilities. The school will draw students from Fairfax, Prince William and Loudoun counties and the cities of Falls Church, Manassas and Manassas Park.

In its first year of operation, the school will have 400 ninth-graders and 125 seniors who were selected from 1,200 applicants after a rigorous three-hour aptitude test and consideration of the student's grade-point average, writing and verbal ability and personal recommendations. The facility is housed in the former Thomas Jefferson High School, whose student body will merge with Annandale High School during the next three years.

Principal Louis R. (Ray) Volrath said the high-tech school is the first of its kind in the country that uses business and industry to support its curriculum, which offers intensive courses and laboratories in telecommunications, engineering, and biotechnology.

Major corporations such as Hazelton Laboratories, Honeywell, AT&T and Virginia Power have donated close to $2 million in state-of-the-art research equipment to the school's labs.

"Sony Corporation is sponsoring our television studio. We'll have enough equipment necessary to produce a television show," Volrath said. "Honeywell and Hewlett-Packard equipped our computer lab with 40 microcomputers hooked up to mainframes. We'll study the computers themselves, not just how to turn out a program, but get a total understanding of the material."

School officials have hired a private security consultant to design a sophisticated security system for the site, which is already guarded with sensitive motion-detector alarms.

"We could go all the way from light beams and cameras to a 24-hour-a-day, seven-days-a-week guard system," said Bill Shadle, assistant superintendent for general services.

David E. Sawyer, assistant superintendent for management information services, is confident the high-tech school will encourage academic excellence in its students.

"There is not a high school in the United States that can touch this facility in terms of equipment and opportunities for students interested in engineering and science," Sawyer said.

In an effort to incorporate the use of computers in classrooms throughout the school system, there will be more advanced-placement computer science courses taught in high schools this year than in previous years.

"We don't want to teach technology for technology's sake," said Mary Anne Lecos, assistant superintendent for instructional services. "The computers will fit well with teaching the writing process and editing phase."

Lecos said the computers, which will be supplied by the school system, also will be used to solve mathematical problems, organize project data and research literature.

There will also be an economics class that will focus on how to keep business records on the computers. Once a week, a member of the Fairfax County Chamber of Commerce will teach the course and help students learn about decision-making in the corporate world, Lecos said.

She added there will be renewed concentration on sharpening students' writing skills "because of concern that the writing skills are not keeping up with the achievement of other skills." Lecos said teachers will take the "holistic approach to writing" and emphasize the creation of ideas and organization over more traditional methods.

Fairfax's 124,403 students will also have a new superintendent, Robert R. (Bud) Spillane, and three new School Board members: Frank Francois (At Large), Kohann H. Whitney (Centreville District) and Carla Yock (Mason District).

Spillane, former superintendent of Boston's public schools, was appointed in February to replace William J. Burkholder, who retired after serving three years as the county's chief school administrator.

Spillane, who was unavailable for comment on the coming school year, has said he favors giving principals more power over their curriculum and greater autonomy for teachers. He also said Fairfax County should lead the nation in maintaining a level of excellence in its school system.

One issue that will also be subject to scrutiny by faculty and administrators is a proposed teacher merit-pay plan. The School Board voted in June to continue looking for an equitable incentive plan after a task force report found last year's pilot program time-consuming and "insufficiently planned."

Meanwhile, students will be busy with testing of their own as thousands of youngsters adapt to unfamiliar surroundings at new and expanded intermediate and high schools.

The ninth grade class of the former Thomas Jefferson High School is merging with Annandale High School -- the first step in a three-year phase-in plan -- and students and faculty from the old Fort Hunt and Groveton high schools are combining at the old Groveton facility to form West Potomac High School.

The Fort Hunt building has been renamed Carl Sandburg Intermediate School and will house seventh and eighth grade students from Bryant and Foster intermediates. Walt Whitman Intermediate School was closed this summer and its students and school name transferred to the old Foster facility, in southern Fairfax County.