It takes Chris Byrne only three minutes to walk from his house to the campus of his Fairfax County high school. That, said the senior, is the easy part.

It takes him five to six minutes more to reach his first classroom.

"I got lost three or four times my first day," he said sheepishly.

The reason Byrne's walk is so long is that he attends James W. Robinson Secondary School, a split-level building that sprawls over 11 acres and that one educator said "looks like General Motors." With its 4,610 students in grades seven through 12, Robinson has four times the enrollment of the entire Falls Church city school system. Located in a burgeoning area of Fairfax off Braddock Road, it is the largest secondary school in Virginia, as well as in the Washington area.

The school, a monument to a brief era in the early 1970s when school planners believed bigger was better, has a proud tradition -- and what many of its teen-aged students say can be a major problem. "It's hard to be an individual in a school this size," said senior Christine Donovan.

Fairfax officials say they will never plan a school as big in the future. But because Robinson cost so much to build and because it educates so many, educators say they wouldn't consider closing the school.

A look at the school, named for a young soldier killed in Vietnam in 1966, before most Robinson secondary students were born, illustrates that it has succeeded despite its size. And its size is huge:

* Too large to be run as a single school, it is divided into six subschools organized alphabetically -- A to K and L to Z -- and by grade level, each with its own principal. Students attend academic classes in their subschools, but take electives and gym outside. If Romeo, a Montague, and Juliet, a Capulet, had attended Robinson, they might never have met, at least not while studying Shakespeare.

"I don't know anyone named L to Z," joked senior Mark Calvert, sitting at a cafeteria table with friends from the first half of the alphabet.

* One hundred girls tried out this year for 24 places on the drill team, and contention to get on the varsity sports teams is so fierce that some students do not even bother.

"I didn't want to face the competition," said senior Carolynn Reinsel, explaining why she plays in the large intramural soccer league instead of vying for the interscholastic team.

* Lunch break begins at 10:35 a.m., and scheduling requires some students to eat their 30-minute lunch in the middle of a class.

* This year, because the school is 600 students over capacity, classes are larger than usual. Shop rooms were turned into academic classrooms and some students had to share lockers until extras were ordered. Next year, even with boundary changes that will send Robinson students to less-crowded schools, it will be 450 over capacity. Lake Braddock Secondary School in Burke, now nearly as large as Robinson, will surpass it in enrollment next fall.

* Ten Robinson seniors will be valedictorians this year, each with perfect grade averages. Graduation will take several hours because each of the 725 graduating seniors will be called up individually.

For all the troubles caused by size, Fairfax educators say Robinson was not a mistake. Teachers and administrators contend the subschools and some homey touches make Robinson seem no bigger than other schools.

And if Robinson seems incredibly competitive because of its size ("You have to be Sir Laurence Olivier to be in the drama club and Johnny Unitas to play football," said one parent), so is the real world, say educators. "Robinson does a good job of preparing kids for everyday life," said Principal William E. Jackson Jr., whose high school graduating class had 35 students.

Almost every student can tell a first-day story about getting lost. But most, like junior Larry Gillespie, said they found their niche when they made friends.

"The only time you really feel it's a big place is between classes," said Gillespie, describing a hallway crush that rivals scenes of stampeding crowds in Hollywood epics. One of 158 blacks at the school, Gillespie will be Robinson's student government president next year.

Robinson was built in 1972 when big-campus programs were in vogue and land scarcity dictated construction of giant schools. Last year, the county School Board changed its policy to require separate intermediate and high schools, each with fewer students -- 1,000 for intermediate schools and 2,000 for high schools.

"You can get too far out and kids simply get lost in the shuffle," said Ruth H. Dell, cochairman of a citizens task force that recommended the shift to smaller schools.

Chris Byrne said it was lonely for him when he moved to Fairfax County two years ago from a 300-student school in Pennsylvania. "It took me a long time to get accepted into the school," he said. But Carolynn Reinsel said size has its advantages: "You meet so many people that you can choose, really. If you don't like someone, they don't mind."

School officials say they try hard to bring the school down to size. New seventh graders come for a half-day tour before school starts. Page D. Styles, principal of subschool 3 (A-K, ninth and tenth grades) sends each of her charges a birthday card and had an ice cream social for the straight-A students last year. "It's an atmosphere of caring for the individual," said journalism teacher Shari P. Balthrop.

Teachers and principals alike say the school works because of its students, most of them products of comfortable homes where academics are important. Shop classes are underenrolled, but 85 percent of the students attend college. Rebellion at Robinson takes the form of an occasional smoke bomb but doesn't go much farther. "I've often thought that if you had a bad student body, you would need the National Guard in here," said teacher Frank Ruth.

There are no bells between classes at Robinson, which Michelle Yasuda liked when she moved from a school in Florida.

"Here, it's kind of calm," she said. The dress code is flexible, and students are free to eat on the lawn.

Some students complain because the administration banned smoking this year and blocked what had come to be known as the annual John Belushi Memorial Food Fight, held around the March 5 anniversary of the comedian's death.

There may be too many students vying for too few spots in after-school events, but their parents are not quite that interested in some adult activities, as Rebecca L. Perry discovered last year.

Perry, who has two sons at Robinson, dropped in on her first PTA board meeting in September, six months after moving to Burke Center from Hawaii.

Although she didn't know anyone else in the room, she was elected PTA president when no one else ran for the office.