Mitch and Amy by Beverly Cleary

Mitch and Amy both think being twins is fun, but that doesn't stop them from squabbling. Amy is good at reading. Mitch is a math whiz. Amy likes to play pretend. Mitch would rather skateboard. They never want to watch the same television show. And they always try to get the better of each other.

Then the school bully starts picking on Mitch-and on Amy, too. Now the twins have something rotten in common: Alan Hibbler. This twosome must set aside their squabbles and band together to defeat a bully!