About this time each year, the tu-tus start flying between Reston and Columbia in preparation for a little bit of holiday magic that will touch Washington's sister new towns.

What these communities have in common besides commuter buses, urban atmosphere out in the woods and contemporary townhouses on little lakes is Julia Redick -- a ballerina with 300 devoted students who is the driving force behind the Conservatory Ballet and its annual production of "The Nutcracker."

"I really don't know why I do this crazy thing each year," sighs the dancer, who was formerly with the National and the Maryland ballets, as she makes one of her twice weekly treks to Columbia with a carful of giggling Reston teen-agers.

"I love the dance and I love teaching it to children, and putting my Reston and Columbia students together [in the "Nutcracker" cast] creates a universality for me between these two places that I love," said Redick.

The ballerina teaches in both towns, with the help of three assistants.

Redick has cast 150 of her students in a one-hour version of the famous Tchaikovsky ballet that has become almost as much a part of Christmas for American children as Santa Claus.

This year's production is the ninth for Redick students, whose parents volunteer to do all the non-artistic organizing and chores connected with the event.

The near-professional productions have won Madame Redick -- as her students call her -- a dedicated following.

"She has such a love and excitement for the dance that it's contagious," said Robyn Berry, mother of a Reston student and a ballet student herself. She is helping organize Reston parents who are preparing for the performance.

"When she yells they sense that she's torturing them in class because she really cares," said Berry's coworker, Nancy Donnelly Benefiel.

It isn't uncommon to hear Redick call out, "If it doesn't hurt it isn't right," or, "Lick the floor with your shoes!" And the kids get the message.

Columbia mother danese Moore heads the Maryland parents who are handling publicity and tickets, making costumes and scenery, working backstage and even selling refreshments during the shows.

"I do this because I think it's really important [for teen-agers] to have something to hang onto during the teen years," said Moore.

"Nutcracker" rehearsals began in early October. To have unlimited time on the weekends, and to avoid burdening parents with carpools, Redick has slumber parties at her Reston home.

After rehearsing over and over again the difficult lifts and other crucial maneuvers in her narrow townhouse living room, the graceful, grownup Sugar Plums and Snow Queens turn into teen-agers again. In jeans and clogs, they make milkshakes, fix each other's hair, chew gum and watch TV.

"The metamorphosis is utterly amazing," said Redick. "They dance so seriously we forget they are just kids, barely even teen-agers."

And when everyone else is finally in bed, she sits in the middle of her floor, still wearing ballet garb, and cuts and sews, bringing the mice to life out of gray felt, the soldiers to attention with pretend brass and braid.

Redick was only 8 years old when the Hungarian government picked her to follow in the toeshoes of her mother, Hungarian prima ballerina Alicia Kish Reisz. The Hungarian revolution changed all those plans, however, and Redick came to the United States with her family in 1957. One of her mother's first jobs in this country, said Redick, was to teach ballet to members of the Oakland Raiders football team. The strenuous exercise and the stretching involved in learning ballet was thought to to be excellent training for football players.

Julia Redick moved to Reston three years ago after seven years in Columbia. She lives with her attorney husband Chad and two sons, Darren, 12, and Jared, 9. The boys are both dancers, and have roles in this year's performance of "Nutcracker."

Redick uses the European teaching stye of having the more advanced students teaching the others "because they understand each step better just by teaching it."

"So this year's Snowflakes will teach next year's and maybe be Flowers themselves," said teacher, who likes to call them "Flakes" and "Flowers."

Columbia ninth-grader Heather Wray will have danced all the "Nutcracker" parts when she becomes a Snow Queen this year.

"I was really shy before, I didn't like to perform," says the blond teen-ager, who dances at least eight hours a week. "But now I love it."

Redick says that she has "lost students because I didn't have a recital at the end of the year," but feels it is important to put students on stage only when they're ready."

Her Reston colleague Susan Jaskolka adds, "With the 'Nutcracker,' unlike a little recital, the kids get to be part of something on a grand scale, and maybe even dance a part they've seen before on stage at the Kennedy Center."

Performances of the ballet are scheduled for Saturday at 2:30 and 7:30 p.m. at South Lakes High School in Reston. For more information, call 435-3354. In Columbia, performances are planned for Dec. 13 at 7:30 p.m. and on Dec. 14 at 2 p.m., both in Oakland Mills High School. The numbers to call are 596-6762 and 979-1634.