LONDON (AP) — Irish band U2 returned to school Friday to put on a surprise class in rock and roll where they formed a half century ago.

The band ripped through a seven-song set including an encore of “With or Without You” for hundreds of students in the schoolyard of Mount Temple Comprehensive School in Dublin and a crowd of others who got word of the gig or — like a construction crew several floors up a nearby building — were lucky to be within earshot and have a bird's eye view.

“We escaped the lab — how’s the experiment going for you?” Bono said as he pointed to the science classrooms.

The band got its start at the school 50 years ago when a 14-year-old Larry Mullen posted a note on a message board reading: “Drummer seeks musicians to form band.”

Originally known as Feedback, the group consisted of singer Paul Hewson, now Bono, guitarist David Evans, known as The Edge, and Adam Clayton on bass.

The rest, as they say, is history, though it would be a couple of years before they settled on the name U2 and not until 1980 that their first album, “Boy,” dropped, featuring “I Will Follow,” the first tune they played for the enthusiastic children.

The 30-minute gig was not quite as secret as it may have seemed. A camera crew was rolling, international news media were gathered and a group of 32 students accompanied the band on stringed instruments for the hit, "One.”

It was part of a promotional push for their new album, “Carnaval De Luz,” which features a duet between Bono and Dolly Parton, who died of cancer last month.

Students, some sticking their heads out of classroom windows, screamed and cheered. They captured the moment on their phones and sang along to the familiar tunes. Some yelled, “I love you Bono!”

Bono thanked his captive audience but noted they had “nowhere else to go.”

As he counted down the signature start of “Vertigo,” with “uno, dos, tres, catorce” (one, two, three, 14), he quipped: “If you’re taking Spanish lessons, don’t take them from me."

In a tribute to teachers, he became philosophical about his time at the school, saying it was where the band began the “humblest and hardest lesson” of learning how much they needed to be taught.

“Part of that started here and the sense was that maybe all we needed was around us, just under our feet — if we could see it in our mates, our wider community that was going to help us get through the next 50 years," he said. "So we want to thank them — and the wider community around this rock ‘n’ roll high school.”