Complex sentence: Advanced and Chamber Strings attend the Anaheim Heritage Festival, perform in Disneyland, and have won several awards while competing against high schools and junior colleges, while the Intermediate Orchestra competes in the Music in the Park Festival and performs in Six Flags Discovery Kingdom.
Split into simpler sentences: Advanced and Chamber String's attend the Anaheim Heritage Festival, preform in Disneyland, and have won several awards while competing against high school's and junior college's. While the Intermediate Orchestra competes in the Music in the Park Festival and performs in Six Flags Discovery Kingdom.