“I don’t have the words” - Music teacher of Australian Idol grand finalist describes pride

"I don't have the words" ❤️

The school music teacher of West Aussie singer Gisella Colletti has described his excitement at the prospect of the 16-year-old winning Australian Idol on Sunday.

Charles Pinkham, the head of music at Corpus Christi College, phoned into Youth Jam's Newsflash podcast and told Isaac he's "so proud".

"I don't have the words. I'm so proud that she has made it here. I think it comes across on camera, she's actually just a genuinely lovely person. Taking that kind of personality into a competition like this, I just think it's absolutely wonderful," Mr Pinkham told Isaac Mulcrone.

The teen singer - who went viral for her performance of 'Defying Gravity' on the show - has the backing of scores of students at the Bateman school with a corner of the library dedicated to Gisella.

"The library has developed a little shrine to Gisella Colletti, so there's all kinds of pinks. It basically reflects her, it's very sparkly, it's very pink, it's right there when you walk in the door," Pinkham said.

A number of students and teachers are also rocking "team Gisella" t-shirts.

Asked how he'd feel if she won, Mr Pinkham said he'd be "elated".

"Excited, elated, wait to see her, see how she's feeling. I honestly don't know yet. This is the first time for me as well, it's all a bit new to be honest with you," the music teacher replied.

Hear more about Gisella's musical journey and how her school is celebrating by clicking play below.