A BATTLE between a class of fourth graders and a major movie studio would seem an unequal fight.

So it proved to be: the studio buckled. And therein lies a story of how new Internet tools are allowing very ordinary people to defeat some of the most powerful corporate and political interests around — by threatening the titans with the online equivalent of a tarring and feathering.

Take Ted Wells’s fourth-grade class in Brookline, Mass. The kids read the Dr. Seuss story “The Lorax” and admired its emphasis on protecting nature, so they were delighted to hear that Universal Studios would be releasing a movie version in March. But when the kids went to the movie’s Web site, they were crushed that the site seemed to ignore the environmental themes.

So last month they started a petition on Change.org, the go-to site for Web uprisings. They demanded that Universal Studios “let the Lorax speak for the trees.” The petition went viral, quickly gathering more than 57,000 signatures, and the studio updated the movie site with the environmental message that the kids had dictated.

“It was exactly what the kids asked for — the kids were through the roof,” Wells told me, recalling the celebratory party that the children held during their snack break. “These kids are really feeling the glow of making the world a better place. They’re feeling that power.”

The opportunities for Web naming-and-shaming through Change.org caught my eye when I reported recently on sex traffickers who peddle teenage girls on Backpage.com. I learned that a petition on Change.org had gathered 86,000 signatures calling for the company to stop accepting adult ads.

My next column was about journalists being brutalized in Ethiopian prisons. A 19-year-old college freshman in Idaho, Kelsey Crow, read the column and started a petition to free those journalists — and in no time gathered more than 4,000 signatures.

Does that matter? Does Ethiopia’s prime minister, Meles Zenawi, care what a band of cyber citizens thinks of him? Skepticism is warranted, but so far Change.org petitions have seen some remarkable successes.

Ecuador, for example, used to run a network of “clinics” where lesbians were sometimes abused in the guise of being made heterosexual. A petition denouncing this practice gathered more than 100,000 signatures, leading Ecuador to close the clinics, announce a national advertising campaign against homophobia, and appoint a gay-rights activistas health minister.

The masterminds of the successful campaigns aren’t usually powerful or well-connected. Mostly, they just brim with audacity and are on a first-name basis with social media.

Take Molly Katchpole. Last fall, as a 22-year-old nanny living in Washington, D.C., she was peeved by a new $5-a-month fee for debit cards announced by Bank of America, with other banks expected to follow. She took an hour to write a petition, her first.

“After a month it had 306,000 signatures,” Katchpole told me. “That’s when the banks backed down.” Bank of America and other financial institutions withdrew plans for the fee.

Soon afterward, she started a second petition, protesting a $2 charge imposed by Verizon for paying certain bills online. In 48 hours it had attracted more than 160,000 signatures — and Verizon withdrew the fee.

Katchpole parlayed her successes into a job with a new advocacy group, Rebuild the Dream, which seeks to improve the economic well-being of middle-class families.

As for Change.org, it is growing explosively. Founded in 2007, it is a B Corporation — a hybrid of a for-profit company and a charity, seeking to make profits for social good — and began to soar a year ago. It is now growing by one million members a month.

“We’re growing more each month than the total we had in the first four years,” said Ben Rattray, 31, the founder. He said that 10,000 petitions are started each month on the site, and that each success leads to countless more copycat campaigns.

Change.org has grown from 20 employees a year ago to 100 now, in offices on four continents. By the end of this year, Rattray plans to have offices in 20 countries and to operate in several more languages, including Arabic and Chinese. He recognizes that the site may be blocked in China, but shrugs.

“If ultimately we’re not getting leaders to ban our site, we’re not doing our job,” he said.

Meanwhile, what about those 14 kids in Wells’s fourth-grade class? I asked them what their next initiative on Change.org would be. They are still discussing options, but one possibility is to reduce waste by calling on companies to stop bombarding the public with telephone books and instead distribute them only to people who request them.

It’s absurd to think that 14 fourth graders could accomplish anything so sensible. But then again, they’ve already shown that the Web can turn the world upside down.