Pop star Lady Gaga and singer Tony Bennett surprised a group of students in New York City by hosting a masterclass on their final day of school.

The two reunited at the Frank Sinatra School of the Arts, a facility Bennett opened in 2001 in his hometown of Astoria, Queens, reports contactmusic.com.

The crooner usually attends the annual graduation ceremony, but is unable to make it to this year's event due to his hectic tour schedule.

To make up for his absence, he recruited Gaga to join him for a special performance and masterclass at the school's Tony Bennett Concert Hall Monday.

Bennett and Gaga began the event by discussing jazz music before answering questions from members of the 700-strong audience.

Bennett also gushed about his pop star friend by telling the crowd: "When I first heard Gaga sing, my reaction was that she is going to be bigger than Elvis.

"She is so bright and intelligent and she has 'it'. In jazz you either got it, the syncopation, the rhythm, or you don't, and when I heard Gaga I said she's got it.`

The two then performed for the audience.

Bennett and Gaga first collaborated on the latter's Duets II album in 2011, covering `The Lady Is A Tramp`, and are currently working on a jazz record slated for release later this year.