Wollemi College's year 6 stage band has grown in confidence and competence in just 13 weeks with the help of brother school Redfield College in Dural.
The Werrington school's head of music Mark Ranftl and Redfield's music co-ordinator Paul Quinn tutor the 31 students in the grade on instruments including the trumpet, trombone, clarinet, alto saxophone and flute.
It is the second year the school has run a compulsory band program.
About 90 per cent of the school's current year 7 students have elected to continue.
"Any instrument when you first start is a bit difficult, and until you reach a certain level with it, sometimes it's hard to enjoy," Mr Ranftl said.
"We found that most of the boys who said they didn't want to try it ended up continuing at the end of the year because they realised they could do it and it's a lot of fun.
"It's pretty fantastic to still have a large band, and next year it will be years 7 and 8 so it will just keep growing."
Mr Ranftl said music also taught skills beyond mastery of an instrument.
"The discipline you get from music and the feeling of ownership of what you've learnt has a really positive impact on the way that the students learn and are approaching their academic life," Mr Ranftl said.
Mr Quinn, who has taught at Redfield College for 21 years, agreed.
"The greatest thing about music is in achieving focus," he said.
"The practice creates a routine, and routine is what they will need to carry them through their HSC."
The Star Wars theme, Amazing Grace and To The Max, Mr Sax are now part of the pupils' repertoire.
A concert and overseas tour are on the cards.