Sir Cumference and the Great Knight of Angleland : a math adventure /
by Cindy Neuschwander ; illustrated by Wayne Geehan.
- Watertown, MA : Charlesbridge, c2001.
- 32 p. : col. ill. ; 25 cm.
School Library Journal
To earn his knighthood, Radius must find and rescue a missing king. His father, Sir Cumference, and his mother, Lady Di of Ameter, give him a circular medallion, (a protractor), that he uses to find his way through a maze of many angles.