DURHAM -- Seventh-grader Jenna Berasa squinted through the lens of a vintage Polaroid ProPak on Monday, her finger pausing above the shutter button. "Is this one your white self or your black self?" she asked classmate Jenny Vitas, who sat on the stairs outside Shepard Middle School pretending to read a book. "This is my white self," she answered quickly, the wind whipping her long, ash-blond locks as Jenna snapped the photo. Figuring out how to represent herself as a black girl wasn't as easy for Jenny. In fact, it was downright uncomfortable. She kept glancing at the two black...