On the carefully manicured lawn at Loreto Mandeville Hall Catholic girls school in Toorak, a sea of girls in white hats waited patiently for the arrival of international superstar Katy Perry.

The Hummingbird Heartbeat singer is in town for her Prismatic tour and will perform Friday night at Rod Laver Arena but on Thursday afternoon she fielded questions from the excitable students, winners of a Telstra-sponsored competition for their film clip that sung the virtues of their school and included Katy Perry lyrics.

The prize was $10,000 for their performing arts program, twenty tickets to Perry's Friday night concert and a visit from the star, resplendent in colourful silk shorts and t-shirt and a Frida Kahlo-inspired braid.

"If I could talk to my childhood self right now I'd say stop worrying about boys, they're very distracting," advised Perry, who shot to fame in 2008 with the lipstick lesbian anthem I Kissed A Girl.