It's the first day of first grade, and the kids who are going to be in Miss Popper's class are really excited. Well, everyone except Carlos, that is! He'd rather stay in kindergarten. Carlos decides he'll go to first grade for one day only, and he'll never come back again. But when Miss Popper reveals that someone new will be arriving on the second day of school, Carlos can't help but return. Who will the new arrival be?