At just 21, Jim Berk, a kid from the San Fernando Valley, started working as a high school music teacher. Within a couple of years, he had turned a woebegone marching band into one of the best in Southern California. Then he moved to another high school to launch a music magnet program. It attracted national acclaim -- and so many new students that officials reversed plans to close it.

The Los Angeles Times dubbed Berk "the Wunderkind of education" in 1992. But after little more than a decade, he was craving new challenges. He moved to a string of jobs in business, including chief of the Hard Rock Cafe chain.

But education was not entirely in his rear-view mirror. In 2007, Berk became chief executive of the Participant Media production company in Beverly Hills. Since then the firm has become known for its "message" movies, such as "Food Inc.," "The Kite Runner" and "The Help," and for educational campaigns that urge audience members to become social activists.

Fans don't just watch a movie; they're encouraged to get involved at Participant's TakePart.com website, where they have an opportunity to, say, pledge to limit food waste, support literacy in Afghanistan, help with a petition effort aimed at protecting farmworkers from pesticides, etc.

This year, as it marks its 10th anniversary, Participant has sketched out big plans for its new television network, Pivot. Over the next decade, the company, which employs 250 people, mostly at its Beverly Hills headquarters, wants to grow a worldwide workforce numbering in the thousands.

Former eBay chief executive Jeff Skoll is a financial visionary for Participant, who talks of building "the most important media company in the world." Berk's immediate job is to grow profits while projecting authenticity in an era when social-action campaigns often come across as mostly marketing ploys.

If the company's ambitions put a lot of pressure on the 54-year-old Berk, he doesn't let it show. He says, "Entertainment is the most effective medium to educate and ignite large-scale change. So in a way, my career has come full circle."

In addition to its didactic films, Participant has won respect for helping finance critically acclaimed dramas such as "Lincoln" and "Charlie Wilson's War," but it has backed a few flops along the way, too, including the Mel Gibson vehicle "The Beaver."

The jury is still out on how much real change a media company can generate. Michael J. Wolf, former president of MTV and now an entertainment industry consultant with Activate, says Participant's campaigns have touched many people because they are heartfelt and gimmick-free.

But Siva Vaidhyanathan, chairman of the media studies department at the University of Virginia, questions the value of activism that takes place mostly online. He says real political change requires the kind of engagement in which individuals raise money, donate time and make long-term commitments.

Nonetheless, Skoll, 49, remains a true believer in the power of the media to raise consciousness and be a catalyst for change. His foundation funds nearly 100 entrepreneurs working for social change, and his Skoll Global Threats Fund is helping identify solutions for such daunting problems as climate change, water scarcity, the threat of pandemics, nuclear proliferation and continuing conflict in the Middle East.

In November, Participant's TakePart.com website drew 3.4 million unique visitors, according to the Internet tracking service Score Media Metrix. Berk says visitors that month took more than 200,000 "actions" -- many of them signing petitions or donating to a cause.

He becomes especially animated when discussing the real change delivered by the movie "Middle of Nowhere," which dramatized the plight of people in prison separated from their families. A special screening for members of the Federal Communications Commission helped prod the agency to help lower costs for telephone calls between inmates and their families. "That's an absolute win," Berk says.

Participant's "The Kite Runner" (2007) brought to light the limited opportunity available for children in Afghanistan. The company's accompanying social action campaign urged fans to support the building of 1,000 libraries in the country. According to company partner Relief International, 650 have been built so far.

The Pivot television channel, launched in August, attempts to extend the social-action model to that medium, though past failures such as Al Gore's Current TV suggest that luring viewers to such fare may not be easy.

Pivot targets a millennial audience with youth-themed reruns like "Buffy the Vampire Slayer" and "Veronica Mars," and runs Participant films such as "Good Night, and Good Luck," as well as original TV programming.

The channel's news magazine, "Take Part Live," aims to give a hip look at current events. Recent stories included "Is Porn Screwing With My Body Image?" and "Paranoia of the Deep," which analyzed the radiation threat from the Japanese nuclear disaster.

Nielsen does not yet measure the size of the Pivot audience, but Participant says it can reach 40 million homes, though some major carriers (including Time Warner Cable) offer it in only selected locations.