Stand Tall by Molly Lou Melon by Patty Lovell

Molly Lou Melon is short and clumsy, has buck teeth, and has a voice that sounds like a bullfrog being squeezed by a boa constrictor. She doesn't mind. Her grandmother has always told her to walk proud, smile big, and sing loud, and she takes that advice to heart.

But then Molly Lou has to start in a new school. A horrible bully picks on her on the very first day, but Molly Lou Melon knows just what to do about that. 

Be sure to look for Molly Lou's other charming books, Have Fun, Molly Lou Melon and Speak Up, Molly Lou Melon!