In the fourth book of this series, Radius, son of Sir Cumference and Lady Di of Ameter, tackles a mathematical puzzle that wins his friend, Vertex, the honor of becoming the king's heir. Whimsical illustrations bursting with rich colors entice readers to join the boys as they creatively use models, math, and a little manual labor to find Edgecalibur, the king's sword. Neuschwander, an elementary school teacher, chooses Euler's Law as a starting point for the joureny and cleverly wraps it up with a nod to the future King Vertex, the Line-Hearted.

Neuschwander retells "The Sword in the Stone" from a mathematical angle. Readers follow along with Sir Cumference and Lady Di of Ameter as their son Radius and his friend Vertex set out to find Edgecalibur. Filled with riddles and puns, the story is sure to delight students with some geometry background. Geehan's bright oil, acrylic, and pen-and-ink paintings include all the visual details that the text needs to help solve this geometrical mystery. If your students have enjoyed the first three books in the series, they will certainly want this one. Make sure to share these gems with your math teachers. The books can be used to support educational initiatives such as multiple intelligences, and students who are strong in verbal/linguistic areas will appreciate the integration of literature into their math lessons.

Sir Cumference equals circumference, get it? This adventure series about a knight in the time of King Arthur centers on mysteries that can be solved only by using math. The latest book, The Sword in the Cone, is a play on the Arthurian legend, in which a boy named Arthur pulled a sword out of a stone to become king. That sword was called Excalibur; in this book, the sword is Edgecalibur. But the prize is the same: The person who finds the sword will be king. Sir Cumference's son, Radius, and trusty pal Vertex set off to seek the sword with only a clue about "shapes that make 2" to guide them. Sound 2 good 2 be true? Read the book, and you'll find it works!

Have you met Sir Cumference? He’s such a wonderful person, along with his wife, Lady Di, and son, Radius. His friends can’t be beat either - King Arthur, Geo of Metry, Sym, Sir D’Grees, King Lell, Per, Countess Areana, Vertex, Sir Tangent, Sir Lionel Segment and others.

Living in Camelot under King Arthur, Sir Cumference and his buddies must work through many complications that require mathematical and logical thinking. During visits to such places as the Mountains of Obtuse, Angleland and the Isle of Immeter, people must be rescued, clues must be found and problems must be solved!

The stories are full of action and suspense that have kept my children enthralled time and time again. The author, Cindy Neuschwander, is an absolute genius in the creativity of these books! It’s beyond me how the books not only have a great plot, but teach math concepts within the storyline – and don’t lose any qualities of living literature in the process!

Depending on the book(s) you read, the following concepts are covered:

* Circumference
* Diameter
* Radius
* Pi
* Angles
* Lines
* Measurement
* Perimeter
* Area
* 3-D shapes
* Counting by 10’s, 100’s, 1,000’s

Any child 1st grade and above will enjoy listening to the stories, but older children (4th grade and higher) will most likely grasp the math concepts best. I used to check the books out from the library until I almost wore my card out rechecking them! Now, I’m the proud owner of each and every one. (A CM homeschool can never have enough living literature on the bookshelves, can it?)