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When "Good Morning America" issued a call for high school students to submit their own rendition of Katy Perry's "Roar" for a chance to win a special performance from her, the entries came pouring in.

All across the country, hundreds of high schools from across the nation sent in their videos, excited for their chance at the prize.

They're not the only ones who are feeling the excitement. "GMA" caught up with Perry at the iTunes Festival in London this week, and the singer was thrilled when she saw some of the contest submissions.

The pop star was particularly struck by the diversity represented in the videos.

"There's just so many different types of kids coming together to make these videos, and it's inspiring to see people just having a great time smiling, being joyful, hopeful, not being kind of weighed down by" the potential pitfalls of high school, Perry told "GMA" on Monday.

Colo. High School's Katy Perry 'Roar' Lip Dub Video Goes Viral

While she acknowledged that she didn't go to "a whole lot of high school," she added: "I imagine from what I went through it can be full of a lot of peer pressure, it can be full of a lot of bullying, it can be full of a lot of rejection and unacceptance, and it seems like through these videos people are being more accepting and just kind of strengthening themselves as a high school body."

The high schools have embraced the challenge in different ways: One school did its own unique choreography. Another made its own roars. And one Colorado high school's lip dub went viral when it was posted online.

Perry was inspired by the creativity displayed in the videos.

"I'm so encouraged, because there's so much school spirit in these little videos, and everybody's coming together, it doesn't matter if you even like my music or not, you're coming together to roar and everybody has their own interpretation … I think it's a wonderful exercise, of school spirit and school strength," she said.

Perry and "GMA" will pick the winning video and broadcast the concert live on "GMA" on Oct. 25 - Perry's 29 th birthday - and the star already knows what she's going to do when she shares her big day with the winning high school.

"I'm going to play 'Roar,' I'm going to play a couple other songs, and just give them their own little private show," she said. "I'm going to serve them up something special, since they made me something special."