The groups included the Pennsylvania Girlchoir from Commonwealth YouthChoirs, Musicopia, Philadelphia Boys Choir, Philadelphia Education Fund/ArtsRising, the Philadelphia School District, Philadelphia Sinfonia, Philadelphia Youth Orchestra/Tune Up Philly, Play on Philly!, Settlement Music School, and Temple University Music Preparatory.
Huxsoll said the 10 organizations had never worked together to plan an event before but wanted to get together to do something for the city's young musicians.
Joe Nebistinsky, Settlement Music School's community engagement manager, said the young students spent time throughout the day in a specific group related to their instrument, such as brass, wind, or percussion. They talked with high school students who served as mentors and practiced their music. One piece they practiced was a special arrangement of Beethoven's "Ode to Joy."
Huxsoll said the students took the rehearsal time very seriously.
"We're not here to throw paper airplanes down the hall because that's what kids sometimes do," Huxsoll said. "The kids here are more committed to music than the average student."
Delia Raab-Snyder, director of Tune Up Philly, said she was impressed with the students' skill level, adding that most came rehearsed and prepared to play.
"If you're going into a group of kids you don't know, you really want to be on your A game," Raab-Snyder said.
Nebistinsky said the festival was not designed to teach how to play the instruments, which ranged from the violin to clarinet to percussion, because the students already knew how. He said most are involved in after-school and weekend music programs.
"The reach, I think, across the city is really massive," Nebistinsky said. "We're giving these kids the opportunity just to sit next to someone from a different zip code, a different economic background."
Giancarlo Kelly, 13, a student at Hill Freedman Middle School on Crittenden Street, said he has been playing the drums for two years. When his music teacher told his class about the Philadelphia Festival of Young Musicians, he said all he had to do was ask his mother.
Kelly, whose favorite musician is Ray Charles, said what he loves about playing the drums is just "hitting it very hard."
Virginia Lam, a music education content specialist for the Philadelphia School District, said the event shows the support for the music in the schools.
"In light of the budget crisis and the closing of 37 schools, this just shows the importance of continuing music education. Today we celebrate music."
Contact Karie Simmons at 215-854-2771, KSimmons@phily.com or @ksPhillyInq on Twitter.