On a stormy day in February, singer-actress-superstar Beyoncé surprised a troupe of young dancers from one of Alvin Ailey’s community programs in New York with the offer of a lifetime: a chance to appear with the star in a Mario Testino spread for Vogue. She talked to us behind the scenes of the high-energy shoot about the importance of body confidence, her status as a role model for young women, and the emotional performance she gave for the president of the United States during the inauguration.