She remembers preparing for her role as the Cat, dressing in her mother's sweater and her sister's pants, a 12-year-old girl with bare feet and shoe-polish whiskers across her cheeks. It was the only time in the concentration camp that the children did not have to wear the marking, the Jewish star, the only time the children could be children.

So when it came time for Ela Weissberger to step on stage this week, when it came time for her to join the children once more--different children, Americans young enough to be her grandchildren--she did not hesitate.

She wore not the marking this time but a silver butterfly pin that caught the lights above, and she marched hand-in-hand with the children, bridging the gap between generations and the gulf of memory.

"We've won a victory," Weissberger sang, just like all those times long ago, "over the tyranny."

The music of Weissberger's memories lived again, reborn with the help of a children's opera camp run by the Washington Opera. For four weeks, 30 children have been training as opera stars-to-be, learning how to audition for roles, how to sing like angels, how to act like fuzzy animals.

All the hard work culminates today and tomorrow with free performances at St. Albans School in Northwest Washington. The summer camp provides children lessons in the art of opera; Weissberger provides the lessons in history.

Weissberger once believed, long ago, that the music died with the children. The opera "Brundibar" closed in October 1944 in a concentration camp in Czechoslovakia after its 55th performance, a bright shining bulb of make-believe in the darkness. Most of the children died soon after, in gas chambers at Auschwitz.

But the children's opera has undergone a revival in recent years, performed across the country in Chicago, Colorado Springs and Kansas City, Mo. The Washington Opera Camp for Kids staged "Brundibar" in the summers of 1995 and 1998, performances that Weissberger attended. This summer, she was invited back for a third time.

The songs always take her back. "In our eyes, Brundibar was the Hitler," she said, "and we would overcome Hitler." In the story, two children embark on a journey seeking milk for their ailing mother but are ridiculed by the village and Brundibar, a wicked organ grinder. To the children's rescue come a Sparrow, a Cat and a Dog, who help them outsmart Brundibar and win enough coins to save their mother.

The young students, selected by audition from the District, Maryland and Virginia, have rehearsed their parts and studied their own pets to get the mannerisms down. There are equal mixtures of nervousness and excitement in the days before the curtain is officially raised and a million questions are asked of Cindy C. Oxberry, the stage director.

Someone forgot his costume shoes at home and opted for sneakers instead. Someone is having trouble keeping the ice-cream scoop props from rolling on the floor, and someone else has sneaked in a hand-held video game.

The Dog steps outside a dressing room, wearing a bulky brown rug of an outfit, complete with flappy ears and tights. "Oh my gosh," said Alexander Arnold, a 13-year-old student at St. Stephens/St. Agnes in Alexandria, "I can't believe I invited some of my friends to this."

It is when the actors are off stage, however, learning about the story behind the opera through Weissberger, that the mood shifts.

On Thursday, in a break between rehearsals at the school, they filed into a classroom and sat, wide-eyed, as Weissberger took them by the hand and led them down the corridors of her memory into one of the dark passages of the 20th century, the Holocaust.

Weissberger, who turned 70 in June, was one of only about 100 children to survive Terezin, a walled-in concentration camp and Jewish ghetto in Czechoslovakia during World War II where some 15,000 children are believed to have perished. Of the 140,000 Jews who passed through Terezin, only 20,000 survived. And of the countless children who performed there in "Brundibar," Weissberger is one of only two survivors today.

Terezin was a nightmarish slum and a way station for trains departing to Auschwitz, but it was used as a front by Nazi Germany as proof to the International Red Cross that Jews were safe from oppression.

Weissberger was 11 years old when she arrived at Terezin from Prague on Feb. 10, 1942, along with her mother, sister, grandmother and an uncle. Her father was taken by the Nazis a few years earlier, and his death remains a mystery to her.

She remembers the feeling, the sounds, the cold bite of the winters at Terezin. The cramped rooms in the barracks, 28 children in a space slightly larger than a public bathroom. Showers were once a month, five bodies under one faucet.

There was talk after a while in the barracks of a performance of "Brundibar." The opera was written by Czech composer Hans Krasa and was first performed in a Jewish orphanage in Prague in 1939. Krasa was later sent to Terezin and eventually died in the gas chambers at Auschwitz.

The Nazis had taken an unusual interest in the cultural life that flourished at Terezin, permitting the ghetto's many artists and musicians to perform there to establish the camp as a showpiece to international observers.

She remembers the audition, shaking nervously, lice in her hair, singing a quick la-la-la for the crew. They told her the part of the Cat was hers. "Cat in an opera? Okay," said Weissberger, her hands folded in front of her as she stood at the front of the class Thursday.

The opera was performed 55 times, and she was the Cat in every one. "Music made us to forget," she told the students, who sat still in their seats, hands on their chins. The opera gave a sparkle of hope, she said, where there had been none. She would hear people meow like kittens as she walked past, a proud smile on her face.

When Weissberger finished speaking, the children had questions. What was it like? Who played the Dog back then? "Remember," she told them after an hour of discussion, "what it means to be free."

Weissberger left Czechoslovakia in 1949 and traveled with her surviving family members to Israel, where she met her husband. They came to America in 1958, to Brooklyn, N.Y., and she eventually became an interior decorator. Her husband died six years ago.

Weissberger now lives in Tappan, just north of New York City, and has dedicated much of her life to educating young opera students about "Brundibar." In September, she will return to Terezin and speak at a tolerance gathering on the very date--Sept. 24--that the opera was first performed in 1943.

Back on stage during a rehearsal, Oxberry, the director, hustled to get every detail just right. Alexander, the Dog, stood near center stage.

In the first week, students went on four separate visits to the U.S. Holocaust Memorial Museum, which helps organize the summer camp. The message hit home. "It's not only acting," Alexander said. "It's a lot more meaningful."

Mary Kavalauskas, a 14-year-old student at Our Lady of Good Counsel in Wheaton who plays the Cat, stepped down from the stage and grabbed Weissberger by the hand. It was time for the victory dance. "We've won a victory," Kavalauskas and Weissberger sang. "We were not fearful. We were not tearful."

Seating is limited for the performances. For ticket availability, call 202-295-2461.

The Post's Web site has a multimedia report on the opera camp, at www.washingtonpost.com.