Book 2 Sir Cumference and the Great Knight of Angleland : a math adventure

The story follows Radius, the son of Sir Cumference and Lady Di of Ameter, as he embarks on a quest to earn his knighthood by rescuing a missing king. Radius uses a circular medallion, which is actually a protractor, to navigate through a maze filled with various angles.

Written by Cindy Neuschwander and illustrated by Wayne Geehan.