The Too-Tall Troll In The Tiny Tollhouse — David E. Hubler

Ages 4-10 Tilden Troll didn't think he was any different from other trolls until he entered the first grade. There, because of his size, he was laughed at and teased by his classmates, who were led by one especially nasty bully. But when the bully found himself in big trouble, only Tilden's size could save him. That became the start of a new friendship and the end of the bullying. The class learned that it's okay to be different, everyone is; but bullying and making fun of others is always wrong.