Shrieks of delight rang out around a Harlem school hall when superstar singer Beyonce strolled in to take part in a dance session.
Students at a New York school were in the middle of performing a choreographed routine to a track by the 29-year-old, when she made a surprise appearance and got in line with the dancing pupils.
But to their credit, the shocked youngsters didn’t miss a beat, despite performing alongside a world famous entertainer. They carried on with their four-minute dance with huge smiles on their faces.
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Beyonce and the students were taking part in a 'flash dance' as part of Michelle Obama's Let's Move campaign.
This involved more than 600 schools around the US simultaneously performing the same pre-choreographed routine in an effort to encourage students to get in shape.
Beyonce's specially-recorded tune, Move Your Body, was the track used for the mass workout. So it was fitting that she was on hand to join in the fun.
"She's beautiful, said one lucky student, 13-year-old Aisha Collier. "I kind of messed up a little when she showed up, but I got back into it. And then I just continued to dance having fun, having more fun because Beyonce was there."
At the same time that the Grammy-winner was getting her groove on, the First Lady was also taking part in the flash dance fun with some Washington school children.
The president's wife, who is a big fan of Beyonce had specially requested the star's help with her youth fitness campaign.