Before landing the role of wizard's apprentice Ron Weasley in Harry Potter and the Sorcerer's Stone, Rupert Grint admits he swam in much smaller ponds. "I'd just been doing, like, school plays and stuff," the 13-year-old sheepishly admits. "One time, I was a fish in 'Noah's Ark,' and now I'm in Harry Potter — that's a big step!"

The charming youngster first applied for his part through a BBC news program. But when he didn't hear back, he stepped up his efforts by showing off his raw talent. "I made this videotape [where] I dressed up as my drama teacher, who's a girl, so it was kind of scary," he laughs. "Then, I made this rap song of how much I wanted to be in the film."

While he claims to have forgotten the lyrics to his winning rap, it clearly made an impression on casting directors. Also helpful was his spooky similarity to Ron, who is Harry's best pal in J.K. Rowling's Potter novels. "When I was reading the books, I always felt I could relate to Ron," he says. "I've got red hair, we both like sweets, we both are scared of spiders and we've both got lots of brothers and sisters."

Grint, the eldest of five children, is already back at work filming the sequel, Harry Potter and the Chamber of Secrets. By now, he's really taken a liking to private tutoring on the set. "We don't get any homework, which is cool," he cheerily shares. "And no detentions, which is even cooler." But his favorite perk of the job? Grins Grint: "Probably the sweets."