The class gathers round as 11-year-old George Garland runs through a selection of "down rocks" - rapid, jerky movements executed close to the polished floor. When he slips and falls there's a cry of "get up, B-boy!"
You can say one thing for pupils at John Cabot city technology college in Bristol. They've certainly mastered the lingo.
Putting hip hop on the timetable is a bold move. But teacher Tom Wykes, a volunteer from the local university, sees it as an opportunity for the kids to let off steam, as well as to hear some half-decent music. He said: "They wanted to bring in their own records to start with. Stuff like Eminem, Akon, Christina Aguilera." He curls his lip. "I make them listen to my stuff."
Needless to say this is a more respectable selection of old school hip hop - a funkier blend of drums, vocals, with plenty of breaks.
Today, George Garland is one of the stars of the school hall. A slight boy in grey tracksuit bottoms and a cap flipped backwards, he entertains his classmates with a lively mix of feints and swivels. George has been practicising his moves with older kids in the local meadows since the age of eight. Today he is mastering swipes, a baffling tangle of movements that result in a sort of human spinning top.
"To be honest, a lot of the rest of them just let loose," Tom said. "But that's what it's about."
Tom is keen to emphasise the aspirational side of hip hop. "Real hip hop is a million miles away from new-school R'n'B-style hip hop," instructs a worksheet handed out at the start of the lesson. "Serious B-boys train very hard and spend a lot of time in the gym. This leaves less time for fighting, smoking, drinking and womanising."
This old-school hip hop ethos is a fitting introduction to John Cabot's after-school learning programme, a brave attempt to fuse attitude and aspiration. Pupils must choose at least one class a week from a menu including hip hop, circus skills, astronomy and something called "pimp my bike".
David Carter, the principal, said: "The curriculum is no longer one size fits all. The important thing is that every kid has a part of the week they look forward to."
John Cabot's innovative approach has helped earn the academy status it will gain this year. It has already divided the year into eight five-week terms and introduced its own Cabot Competency Curriculum, which coaches pupils in life skills.
But what life skills are they learning from hip hop? The art of womanising on the sly, apparently. "Trust me," concludes the worksheet. "When you're the one in the club break-dancing and not drinking - women love it."