Sir Cumference and the Sword in the Cone

King Arthur has hidden his sword, Edgecalibur. The first knight to find the sword will be the next king. Can Sir Cumference and Lady Di point Vertex, in the right direction? Will Vertex's sharp thinking give him the edge? Join Sir Cumference, Lady Di of Ameter, and their son, Radius, in this new adventure where they race to help Vertex find the sword and discover the secrets of cubes, pyramids, cylinders, and cones.

In this wonderfully illustrated series, go on math adventures with Sir Cumference, Lady Di of Ameter, and their son Radius. Each book presents a mathematical concept in such a way that it allows students to fully comprehend "how" and "why" the characters solve their unique problems.