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.

A book that introduces basic math concepts through a story set in a medieval setting. The story revolves around King Arthur and his knights who need to find a better table shape for their meetings. Sir Cumference, his wife Lady Di of Ameter, and their son Radius help design tables of different shapes, including a square, parallelogram, octagonal, and oval table, before settling on a round table, which proves to be the best for their discussions. Written by Cindy Neuschwander and illustrated by Wayne Geehan.