A FORMER ballerina who once enchanted European audiences has grown into a 63-year-old pixie who bewitches young dance pupils and turns the suburbs of Fairfax County into an enchanted forest.

"The trick of it is this," says Christina Heimlich, with remnants of a German accent. "When children go to ballet school it's all technique and quickly gets boring. What I can do to make it fun is make them feel the music. So I tell them stories."

For more than 20 years she has filled young minds with the Brothers Grimm and trained young bodies to interpret the folk tales and legends. In fact, Christina Heimlich and her students have become something of a legend themselves within Fairfax County's arts community. Heimlich has been actively involved with Wolf Trap for 12 years, and will be chairman of the International Children's Festival gala in September. She and her students have performed on local public television and are a regular attraction at embassy parties and international festivals.

The Christina Heimlich School of International Dance has about 150 students between the ages of 4 and 16 in Fairfax, Annandale and Burke, who are trained in classical ballet but also learn ethnic dancing. The best ones join The Christina Heimlich Dancers, a group of 18 girls and boys who perform regularly at special events such as the International Fair at the Sheraton Park Hotel and the International Children's Festival at Wolf Trap.

The folk troupe is Heimlich's pride. She choreographs all the dances, designs the sets and splices together tapes with the appropriate music. Her attic, she says, extends the entire length of her spacious Fairfax home and is stocked to the brim with costumes.

During a recent rehearsal, Hansel and Gretel practiced curtsies before the mirror of Heimlich's studio, while tiny Chinamen tugged on an imaginary rickshaw. Gypsies and Cossacks twirled, and clowns tumbled about a Maypole. Undaunted, Heimlich administered this circus by sitting erect in a high-backed chair, tapping a wooden baton on the floor and singing commands.

"If you can't feel the tip of your finger you aren't dancing," she said sternly. "Don't have that fish hanging there! You have hands!

"If you smile at the people they smile right back at you!

"Make that schnipp-schnapp with the music!"

And to a shy little Hansel, bravely trying to march toward Gretel: "C'mon, Hansel! Full of sauerkraut!"

The studio walls are covered with recent pictures of these characters, and not-so-recent photographs of Heimlich herself. In them she is slender and blond, poised on the tip of her toes; her chin, nose and enormous blue eyes tilt upward. That was a time of innocence, in the pre-war days when she toured England and the continent with the Sadler Wells Ballet company.

Heimlich, who was born in Silesia, doesn't like to dwell on the war, which she spent in forced labor, but she doesn't mind talking about her big break, which came when she was 16 and studying in Berlin's Russian Ballet School.

"Now here comes a real fairy tale," she begins. One of the little swans in a Sadler Wells' production of "Swan Lake" hurt her ankle. The understudy had the flu. Heimlich was chosen for the part, which she performed so successfully that she remained with the group.

And it's with obvious pleasure that she dusts off a 1949 issue of Time magazine, which includes her picture in an article on postwar Berlin's "Radio for the American Sector." Her then-future husband, an American officer named William Heimlich, was its founder and director. They met while she did a feature called "Voice of Berlin." "Pretty, blonde Christina Ohlsen," as Time called her, was famous for the childlike role she created on the airwaves. Her task was reading the day's headlines, but she did so in a small voice, repeating incredulously, "I don't understand. I'm too little to understand."

In 1951, she was invited to the United States by the State Department and married Heimlich shortly thereafter.

Soon she began teaching, fulfilling a life-long dream. "I couldn't let go completely," she says of dancing. Her first class had five neighborhood children in it. Now, a constant parade of young dancers winds through her Alpine-style home, and many grown, faithful pupils visit her regularly.

One student has become her prote'ge' and Heimlich plans for her to take over the school and performing group when she retires. Lisa Clohisy, 23, began studying with Heimlich 12 years ago and became "hooked." Because illness caused Heimlich to stop dancing six years ago, Clohisy conducts many of the classes and works with the performers on Heimlich's choreography. Clohisy says she wants to carry on the Heimlich method of teaching dance: "That's why I'm here. Where else could I learn it?"

It's a method born of imagination and discipline. "I always liked the idea of 'The Sound of Music,' the idea of dancing with children," Heimlich says. So she keeps dreaming up new schemes--a Maypole of colored streamers and flowers, an enormous wrapped box filled with live toys, a wheel of fortune with dancing children as prizes.

"I think in this age it's wonderful that you can still fascinate kids with this," Heimlich says. "They feel the creativeness of it."