Under the fluorescent lights of the Glenbrook North choir room, freshman Rachel Harris rose to introduce herself. She tried to fake a confident smile, though her heart was beating out of her chest. Surrounding her was a group of girls, all seeking the same thing: a spot in the Glenbrook musical “Mamma Mia.”

“It’s OK because I love [theater],” said Harris. “I would rather be so busy and exhausted and feel overwhelmed but just full of so much joy than not be doing it because I can’t imagine my life without theater.”

Assistant Director Kelsey Nichols said the audition turnout this year was the third largest in Glenbrook musical history, with 157 students between Glenbrook North and South auditioning. After calling back 121 students, Director Mark Maranto and Nichols selected 84 of them to participate in the musical. Students could also get involved through stage crew, pit orchestra or assistant director work.

The collaboration between North and South students is what separates the Glenbrook musical from other shows. Maranto said that when casting, he tries to pair students from GBN and GBS in lead roles like Sophie and her fiance Sky.

“I think it’s really fun to see how much talent comes out from both schools to audition and being surprised by thinking in my mind like, ‘Oh that actor might make a great “this role,”’ and how it sometimes is the total opposite of what you thought it would be heading into it,” Maranto said.

For the first few weeks of rehearsal, singing, choreography and blocking all happen simultaneously with different groups of the cast doing different tasks. Closer to opening night, the ensemble, leads, crew and pit orchestra all rehearse together in the auditorium.

“[My favorite part is] probably when we get more into tech week because then you get to see the set is done, the lights come into play and [the cast] puts on their costumes,” said Nichols. “That’s when it really feels real.”

The show is scheduled for 7 p.m. on May 1 to May 4 in the Norman E. Watson Auditorium at GBS.

Harris said, “When I was little, my dream was to be in the Glenbrook musical. I was like, ‘Oh my God, one day I hope and pray that I can be on that stage.’ I idolized people who were performing, and so to be doing [the musical], I’m really excited to just get to do that.”