Musical director John Buchanan said the choir, formed of pupils from years 11-13, took the stage at the Sydney Opera House last Monday and performed in front of a packed audience.
The girls also participated in a workshop with international teaching artist and operatic baritone Andrew Eisenmann, of Rancho Mirage High School, in the Southern California desert.
Choir member and one of the leaders Ally Hamill (17) said the workshop with Mr Eisenmann ``helped us a lot- he was very boisterous, he made us do a lot of weird exercises.
``He made us mouth shapes and facial expressions that would help us sing.''
Another highlight was making friends with members of the Fountain Valley High School Troubadours, a school choir from Orange County in Southern California.
``They were really quite friendly,'' Miss Hamill said.
A celebratory meal at the Hard Rock Cafe turned into ``something like High School Musical'' when another choir was there at the same time, and they began singing across the cafe, Miss Hamill said.
``It was pretty cool - it was like a party environment, everyone was singing along.''
Over 900 pupils took part in the festival, which included wind bands, orchestra, choirs and jazz bands from around the world.
- Simon Henderson