Hans Krasa’s 1938 children’s opera Brundibár has become a symbol of defiance in the face of powerlessness. Krasa originally rehearsed the opera with the children of a Jewish orphanage in Prague. Tragically, the entire orphanage was shipped out to the Theresienstadt concentration camp before the first performance. Krasa, who was also interred, responded by re-writing the score from memory and proceeded with the performances — which, it turns out, were loaded with anti-Nazi symbolism. That defiance slipped past officials so handily that Hitler actually recorded one of the productions for a propaganda film. Still, there was no happy ending. At the end of filming the entire cast, including Krasa, was shipped off to the gas chambers at Auschwitz. “Out of 15,000 children in the camp, only 100 survived,” says Eugenia Strauss, executive director of CityMusic Cleveland. “Yet the opera remains a statement of hope, and a warning against all forms of intolerance and hatred.” Beginning May 1, CityMusic is launching a series of fully staged Brundibár performances, featuring the Cleveland Orchestra Children’s Chorus and the Cleveland School of the Arts chorus. Ryan McAdams, music director of the New York Youth Symphony, conducts. Alison Chase, choreographer and founder of Pilobolus Dance Theatre, directs. Tickets are $20 for adults, and $10 for children and students with ID. Performances continue through Saturday May 5; curtain is at 7:30 p.m. at John Hay High School, 2075 Stokes Blvd. Buy tix and learn more on the website.