On the spring calendar at Bishop Denis J. O'Connell High School in Arlington, the annual Superdance to benefit the Cystic Fibrosis Foundation has become as certain an event as the senior prom.

And it seems just as certain that when the dance is over and the pledge money is collected, the school will remain the foundation's largest high school contributor in the country.

Since the first dance in 1976, the school has raised over a quarter of a million dollars, collecting an average of $28,000 for each of its charity dances, according to officials in the foundation.

Other schools have collected as much as $10,000 at a single fund-raiser, but O'Connell is way above the rest, said Richard Bedea, executive director of the foundation's metropolitan area chapter.

This year the school hopes to collect $40,000, surpassing the record set three years ago. About 1,000 students are expected to dance in the 12-hour event that will go from noon to midnight this Saturday.

The first dance was held 10 years ago, after an O'Connell student, Brenda O'Donnell, died from cystic fibrosis as a sophomore. Three other O'Donnell children, including Maura, who graduated from the high school in 1978, also died from the disease.

Cystic fibrosis is an inherited disease of the lungs and digestive system that has affected about 50,000 children in the country.

Each year 27,000 children are born with the disease. Most who have it will die before they are 20 years old, Bedea said. There is no known cure.

The money raised by the O'Connell students will fund 12 research centers across the nation as well as three Washington area clinics, Bedea said.

In subsequent years, the mother of the children, Maureen O'Donnell, a Latin teacher at Woodson High School in Fairfax, has come to speak to students at O'Connell to encourage them to become involved in the dance.

O'Donnell said that although she's spoken several times to O'Connell's 1,600 students at the kickoff assembly two weeks before each dance, it's always difficult for her.

"It's very hard to control the tears. In my mind's eye, I see my own daughter in the stands. It brings back lots and lots of memories. But I wouldn't give up the chance to talk on cystic fibrosis because there's other kids out there waiting for a cure," O'Donnell said.

"They were my teachers in courage and strength," said O'Donnell about her children. She also said that her family's experience has strengthened her commitment to see that her students make the most of their talents.

The last O'Donnell, Bridget, one of two who didn't have cystic fibrosis, graduated from O'Connell in 1981, but the memory of her sisters and brother is kept alive by the annual Superdance.

"Being at the assembly really does it to you. It motivates you to go out and raise all you can," said senior Laura Eakin, 17, one of the students involved in organizing the dance.

O'Connell's Student Council Association began setting the groundwork for this year's dance three months ago. Senior Maryann Gallivan, 18, is president of the student association and in charge of organizing 13 committees that take care of everything from music to publicity to food for the dancers, which is donated by area businesses.

The students also rely on O'Connell alumni to make donations and help out in other ways. This year, two local rock bands made up of alumni, the Observers and LEX, will perform free of charge.

Gallivan said that the students are optimistic about this year's Superdance goal of $40,000, which is $4,000 more than the previous high mark in 1982. "Each year we try to improve. This year we really wanted to challenge ourselves," said Gallivan.

About 75 percent of the students will dance the entire 12 hours, which will be divided into various musical categories from Motown to Beach Boys where students can opt to dress in costume. Each student will get six 10-minute rest periods and time off to eat.

Several Washington Redskins players and the Redskinettes cheerleaders will also come to encourage the dancers, said publicity chairman, senior Tia Gillanders.

Another senior, Mark McCrery, said his older siblings who helped organize previous Superdances sparked his interest to become involved. "It's a good application of what we learn at O'Connell. It does good for our community here and society in general," McCrery said.

O'Connell Principal Al Burch, who has seen all 10 Superdances, said he is proud of his students. "It brings out the best in us. I see our kids working hard. The caring and love should be brought out -- that's what we're here for," Burch said.

Mike Conway, faculty moderator for the Student Council Association, said it's never a question of whether students should be involved in a fund-raiser, but only a question of where they spend their energy.

"I'm amazed how they pick up the ball and run," Conway said.