On Friday, a teacher told his class that he was going to give a surprise quiz the following week. One clever student—we'll call him Jamie—went home and thought about this pop quiz. He didn't know the subject very well, and was upset that he was going to miss his whole weekend to study. Jamie tried to figure out what day the quiz might be. First, he noticed that it couldn't be Friday, because if they got to Thursday and hadn't had the quiz yet, then everyone would know it was on Friday, and the teacher had said it would be a surprise. Friday is out. Well, now the text couldn't be on Thursday, because if they got to …