Health and Human Services Secretary Kathleen Sebelius addresses students and teachers at Stuart-Hobson Middle School before an early screening of bullying documentary "Speak Up" on Wednesday. (Patrick Svitek/Medill)

WASHINGTON — Students and teachers at Stuart-Hobson Middle School wrapped up their school day Wednesday with a stern lesson on bullying from some of the country’s strongest voices on the topic.

The pupils and their teachers attended an early screening of “Speak Up,” a half-hour documentary on bullying championed by Health and Human Services Secretary Kathleen Sebelius, who sat front row in the school’s auditorium.

The movie, slated to premiere on Cartoon Network on Sunday, opened with a brief video message from President Barack Obama, who hosted the first anti-bullying summit at the White House last year.

“I care about this issue deeply,” he told the students. “Not just as a president, but as a dad.”

Speaking to the entire student body, Cartoon Network President Stuart Snyder stressed that the need to tackle bullying at all ages is more pertinent than ever. He cited statistics showing someone is bullied on a school playground every seven minutes.

And 85 percent of the time, no one steps in to help, Snyder said.

The simple act of “speaking up,” he added, prevents the antagonistic act half the time and typically brings it to an end within 10 seconds.

Sebelius said anyone who tries to downplay the perils of bullying is “flat-out wrong.”

“To stop it, you all may have the most powerful voices,” she told students. “You need to be heard. To stop it, we all need to speak up.”

“Speak Up” profiles several bullying victims and how they overcame their tormentors over the years.

One of the documentary’s subjects, 15-year-old Aaron Cheese of Atlanta, participated in a panel discussion moderated by CNN anchor Don Lemon after the Wednesday viewing, which was cut about 10 minutes short due to technical difficulties.

In “Speak Up,” Cheese recalls being mocked for the size of his lips and the glasses he had to wear at an early age.

Lemon told Cheese that he had been teased for “pointy ears” as a child.

“And now I’m on television,” Lemon quipped. “So there you go.”

Sunday’s television premiere of “Speak Up” comes two weeks before another film on the topic, “Bully,” rolls into theaters nationwide.

That take on the dangers of peer-to-peer intimidation has spark a national controversy over its R rating, which prevents the documentary from being shown to its intended audience — those 17 and under — without a parent or guardian present. The Restricted rating stems from a scene in which the F-word is reportedly used six times to harass a bullying victim.

Last week, Katy Butler, a 17-year-old high school student from Michigan, delivered a petition with more than 200,000 signatures to the Motion Picture Association of America’s headquarters in Sherman Oaks, Calif., asking officials to lower the rating to PG-13.

The industry group has already rejected a ratings appeal, leaving director Lee Hirsch with three options: Release “Bully” with its current R rating, censor the coarse language to accommodate a PG-13 rating or release it without an MPAA rating. Most theaters regularly refuse to carry an unrated flick.

Sebelius touched on the tale of two bullying movies in a news conference after Wednesday’s “Speak Up” event.

“I know there’s been a question about language [in “Bully”], but, frankly, bullying is often a difficult language to hear,” she told reporters. “It’s often nasty, mean speak, but using it as a positive impact, I think, could be very beneficial.”

“Speak Up” director Lee Hoffman said he thinks Hirsch is “going after a very different audience” with “Bully” — one that is older and involves bully victims facing a different kind of risk.

He called his work for Cartoon Network a less dramatic approach but one just as important.

“I think they want to get at what’s often overlooked, which is the smaller, everyday testing, where it makes you a worse student, it makes you fearful to go to school, but doesn’t rise to the level of suicide or all these really tragic moments,” Hoffman said. “…It shouldn’t be, ‘Well, I didn’t feel like killing myself, so I guess it’s not important.'”

“Speak Up” airs 5:30 p.m. EDT Sunday on Cartoon Network, with an encore showing at 8 p.m.