It was no secret that David Archuleta could sing -- students and teachers had heard him belt out holiday carols during Spanish class and an opera aria at a school arts festival.

None of that was reason enough to believe the junior at Murray High School would transform from a shy and impish 17-year-old to a fast-rising star on "American Idol."

"He giggles every time you confront him," Archuleta's 11th grade English teacher Chantel Thackarey said. "I can't believe how well he's doing because he's just so painfully shy."

Week after week, Archuleta seems to out-sing the competition on the top-rated Fox television show, winning the hearts -- and votes -- of viewers. Idol judge Paula Abdul has said Archuleta is "destined for superstardom."

"He commands the stage," said Dean Kaelin, a vocal coach who has worked with Archuleta over the past six years.

In spite of his obvious talents, Archuleta has kept a low profile on the Murray High campus. An A student with a quiet demeanor, he wasn't among the school's most popular kids, nor the star of school plays.

"I didn't see it coming," said Murray High student body president Adam Ward, who witnessed Archuleta's Spanish class serenade in 2006. "He's this little guy, and he just belted that music out. It was amazing. He's a notch above."

Kaelin recalls a similar reaction when an 11-year-old Archuleta first came to him for vocal training prior to appearing on the CBS network TV talent show "Star Search." (He won the junior singer division in 2004.)

Even then, the boy with dark hair and piercing eyes sang with a maturity beyond his years, Kaelin said.

"The thing that's unique about David is his sense of musical styling and phrasing. The one thing that is hard to teach is the sense of the music, the feeling of the music and the rhythm," Kaelin said. "It's intuitive. Sort of like a sixth sense." Watch the best and worst of the latest "Idol" »

Maybe talent is just in Archuleta's genes: His father, Jeff Archuleta, plays the jazz trumpet; and Lupe, David's Honduras-born mother, a singer. Both have performed professionally, and they've exposed their five kids to a wide range of music, Kaelin said.

David Archuleta started singing at about age 7, stopping only to recover from a paralyzed vocal chord discovered about the same time puberty began to deepen the teen's voice.

Kaelin describes his student as a focused, hard-working musician who sets specific goals for technical growth and understands that songs are stories, too, Kaelin said.

"It's about connecting with people and connecting with the song. It really wouldn't make a difference if he was on TV with 40 million people watching or if he was singing in a church or in a rest home."

Out of the spotlight, Kaelin calls Archuleta a genuinely nice kid whose family and faith keep him grounded.

"My personal belief is that he has no idea what a big deal he his," Kaelin said.

Big deal indeed.

Beyond viewer votes, Archuleta's soaring success has spawned dozens of fan sites on MySpace and Facebook -- most seemingly from teenage girls -- that wax about his heartthrob good looks and prognosticate about his being crowned the next "Idol." Other fans say they've been brought to tears by Archuleta's "gift," and a handful of young women have proposed marriage.

Back home in Murray, a growing fan club of students and teachers said they tune in weekly to watch.

"I have both my kids going at my house the whole time the show's on, with two phones, getting in as many votes as they can," school principal Scott Bushnell said a bit sheepishly. "I've heard many stories of students texting more than 100 times for David."

Thackarey said Archuleta deserves every accolade. Embarrassed by compliments and always more interested in others, Thackarey said Archuleta isn't driven by some hope of fame.

"I can't picture David saying 'I want to be a rock star, I want to be famous,' " said Thackarey. "He's more like, I want to do music because I love it. He's a follow-your-bliss kind of guy."