GAINESVILLE, Fla.—It was a sticky Thursday afternoon in the middle of summer break when dozens of teenagers walked through the doors of their high school.One of the world’s most dominant teams was about to start math practice.There was probability in one classroom and pre-algebra next door, code-breaking down the hall and number theory around the corner.The students would spend the rest of the day teaching each other.Continue reading your article witha WSJ membershipa WSJ membershipAlready a member?"