From left, sopranos from Crystal Lake South High School, Mallory Litzo, Aleashea Preston, Mitali Tambe and tenors from Prairie Ridge High School Jim Gritschke, Cody Hochstatter and Eddie Smith rehearse their parts for an upcoming performance of Antonio Vivaldi's "Gloria." The choir, made up of 150 students from the two schools, will be accompinied by a 13-member professional orchestra for two performances on April 8.