High School Musical started as a modest, low-budget Walt Disney movie shot with a bunch of no-name kids in Salt Lake City, Utah.

Now it is the most important live-action franchise at the House of Mouse. With many of the lead performers such as Zac Efron becoming stars, High School Musical is a phenomenon. It boasts two TV movies, a higher-budget film set to shoot soon as a future theatrical release, several soundtrack CDs, a stage show and this week's debut of High School Musical 2: Extended Edition on DVD.

Kaycee Stroh, one of the singing, dancing and acting leads in the franchise, figures she knows the main reason for the remarkable success of the series, especially among youngsters.

"I think all of our hearts were so in it and the chemistry between the 10 of us (the core group of youthful co-stars) was so fantastic and I think our characters were so well defined, you can relate to all of our characters. There is one of each in every high school."

Stroh (a 23-year-old who plays Martha Cox) is on a promotion tour this week with three colleagues: 17-year-old Chris Warren Jr. (a high school football standout who is giving up sports to play Zeke Baylor), Olesya Rulin (the trilingual, 21-year-old Russian who is breaking out as Kelsi Nielsen) and Ryne Sanborn (an 18-year-old who gave up his dreams of Olympic hockey to play Jason Cross).

Sun Media talked to the four of them on their Toronto visit.

Warren says that the musicals give younger children positive role models to grow into in high school but also highlight problems they will have to deal with.

"No matter what high school you go to or where you grow up, you deal with these certain issues that are in the movies. It really covers the bases of everything so everybody can relate to it. That's why everybody is into it, especially kids, because they're going through it right now."

Warren, ignoring cynics who have attacked the High School Musical series for being sentimental and simplistic, says a lot of others kids' entertainment is "cheesy or watered down" and feels fake to him.

"But this, I think, is really genuine and pure and that's why it's so successful."

Stroh loves that the franchise has revived the art of musicals for children, just as Chicago and Moulin Rouge did for adults. "I'm so grateful for that because, as a little girl, I told my mom once: 'Mom, I love musicals and I'm going to bring them back one day!' How ironic that my first movie happened to be this huge musical phenomenon."

Warren says one of the "secrets" is Kenny Ortega, the choreographer and director. "Being a genius helps!"

Stroh adds: "... and having people whose hearts are in it, who are committed to it, because practice makes perfect and that's truly what it takes to put on a good song and dance."

It is a team effort, says Sanborn. "I think we all brought out own kind of spirit to the movie and just bonded on an emotional level. You can't fake that stuff."

Rulin agrees: "It rarely or never happens that you get 10 kids who like each other and who can play together well and can do so in the course of what will be three years.

"Every one of us has our own talent. It definitely shows through in the movie and I think kids can relate to that and adults can relate to their childhood through that. They can relate to the daily traumas of high school."

Rulin is not embarrassed by the stereotypes in High School Musical, such as the rich-bitch girl played by Ashley Tisdale or the hunk jock played by Efron. "Every stereotype exists from some article of truth," she says. "At the same time, this movie is so innocent. I think it's such a breath of fresh air."

Hudgens co-star says photo scandal overblown

The Internet "scandal" over nude pictures of Vanessa Hudgens was overblown and an invasion of her privacy, says actress Olesya Rulin, Hudgens' co-star in the High School Musical series.

"I think what gets confused in the media is that everyone is as personal as the day, and we are not our characters, and we are older than we portray."

The 21-year-old Rulin plays Kelsi Nielsen in the musicals. In interviews for this week's DVD debut of High School Musical 2: Extended Edition -- which includes behind-the-scenes looks at the co-stars in rehearsals -- Rulin says there is a problem in having the public pay too much attention to the private lives of performers.

"I think there is a lot of danger in that. I learned that first-hand. I went to the zoo and some of my personal pictures got on to the Internet."

Without mentioning Hudgens by name, Rulin says the scandal was no different: "At the end of the day, everyone makes mistakes and everyone makes discoveries and everyone has skeletons in their closet. Normal people, though, just have the privilege to keep it to themselves.

"And everyone 17 is crazy and everyone has the right. If you take that right away from someone, then that is a cardinal sin. You are meant to experiment. You are meant to bump into corners. And that's how you learn."