The Teacher is NOT a Troll (Paperback) (ISBN-13: 9780645537925)

Dai and Bear are ordinary kids.

Well, not totally ordinary. There is the fact that they fight with swords and are training to be knights. And their mother is a dragon-wrangler who works for the fire department. And their dad works for the city council, making sure no one builds a shed over a goblin warren. And they regularly fight monsters.

Perhaps they're not that ordinary.

Oh, and they're almost certain their headmaster is a troll.

There's still some doubt about the teacher though...