It was barely two weeks before Christmas, and the middle school students were struggling to sing "Jingle Bells" and "The Twelve Days of Christmas." Muffled voices wandered through the verses as though the lyrics weren't as familiar as the season itself.

They weren't.

Many of these 11-, 12- and 13-year-olds didn't grow up caroling every December. Some had never heard these songs.

Welcome to Sterling Middle School, Loudoun County's most diverse campus. Its minority students, 34 percent of the school's enrollment, speak 17 different languages.

"We value the diversity," Principal Charles J. Haydt said. "Kids understand that there's nothing wrong with being different."

They tout it in classroom decorations and after-school activities. They brag about it to outsiders. And the teachers encourage it.

"The people who are there--the teachers and the administrators--they are really great with the diversified student population," said Roberta Ruths, the parent of a Sterling Middle School graduate and a current sixth-grader.

Something must be working: Haydt, who has led the school since 1991, was named Loudoun County's outstanding principal for 1999.

Cultural diversity is not the only challenge for the school community. Nearly 15 percent of students receive a free or reduced-price lunch. The student population has bulged to 1,150 even though the school was built for 10 fewer children. The preteen population--many of them obsessed far more with puberty and pimples than academics--can be trying.

"When people ask me how many of my 1,100 students are at-risk students, I tell them I think I got 1,100," Haydt joked. "It's an interesting age."

Built in 1971, the low-slung brick campus off Sterling Boulevard is old and cramped. Six portable classrooms handle the overflow of students, who must walk outdoors along a concrete path to get to the trailers. Haydt, who stands nearly 6 feet 4 inches tall, can almost reach the opposite sides of the hallway with his outstretched arms.

If students, parents, teachers and administrators could change one thing about the school, they unanimously agree it would be its physical plant.

"I think you have to consider the Sterling Middle School needs more," said PTA President Mark Gunderman, whose daughter Lisa is an eighth-grader. "A lot of times, people forget about the refurbishment of the older schools."

Ruths said she "seethes" when she visits newer middle schools, such as Harper Park Middle in Potomac Station and Farmwell Station Middle in Ashburn, where there's an abundance of parking and no trailers. But "the building doesn't teach the kids," she said. "The teachers teach the kids."

The Sterling Middle School community is proud to argue that newer and bigger is not always better. In this older suburb, all of the schools are within walking distance. The annual redistricting that plagues Ashburn parents hasn't happened in Sterling in years.

"That's certainly a plus," Haydt said. "If [Sterling] kids started in kindergarten together, chances are they'll end up in high school together."

But every year, a handful of students opt not to attend the neighborhood high school, Park View, and instead enroll at Thomas Jefferson High School for Science and Technology, a Northern Virginia magnet school.

More than 30 percent of all Sterling students enroll in at least one honors class. About 24 advanced eighth-graders take geometry, and there are nine algebra classes for others who want to take the accelerated math course.

But students who have not attained those academic achievements are not ignored. Every quarter of the school year, the Parent-Teachers Association gives a pizza and make-your-own-sundae party for students on the Honor Roll. Also invited are members of the B.U.G. Club (Bring Up Your Grades)--students who have shown vast improvement on their most recent report card even if they haven't gotten as far as the honor roll.

The biggest change during Haydt's tenure, by far, has been the explosion in the number of minority students, with roughly equal numbers of Asian, African American and Hispanic students.

"Ten years ago, we could count the number of [minority] kids on one hand," Haydt said. "Now you need a calculator."

Many Hispanics are from the war-torn countries of Nicaragua, El Salvador and South America, where their education was often interrupted. Some arrive with limited schooling even in their native tongue and are now immersed in English.

"I like the classrooms, I like the teachers," said George Gomez, 14, an eighth-grader who came to Sterling two years ago from El Salvador. He answers an emphatic "no" when asked whether he'd like to return. "In my country, you cannot find work."

Faculty and staff members continue to brainstorm ways to meld the cultures. Last year, they held "International Night" in the cafeteria and invited the staff and the community. The tasting party included about 50 desserts from different cultures, homemade by parents, who sampled one another's treats.

Cafeteria menus have been redesigned to reflect diverse eating habits. Pork is outlawed and chicken is listed almost daily. Many students are given a pass because they fast during Ramadan.

One of the school's most beloved teachers is Kurt Engel, an eighth-grade civics instructor who has been offered a job at a new school in fast-growing Loudoun and another at Loudoun's higher-paying arch rival, the Fairfax County school district. A 23-year veteran, Engel said he wouldn't dream of leaving.

"I believe in loyalty," he said. "This school has always treated me well. There's something going on all the time."

In a fast-growing county where a 10-year-old school is now middle-aged, Sterling Middle School is a treasured antique.

CAPTION: Sterling Middle School Principal Charles J. Haydt watches as students Curtis Coker, 11, left, and David Nguyen, 11, shake up a batch of ice cream.

CAPTION: "We value the diversity," says Charles J. Haydt, principal of Sterling Middle School, here looking over work by Alex Rivera, who is learning English as a second language.