Title of Book:
Author:
Publisher:
ISBN:
Sir Cumference and the Dragon of Pi: A Math Adventure
Cindy Neuschwander
Charlesbridge/1999
978-1-57091-164-4
Grade Levels for Recommended Use: Fifth Grade – Eighth Grade
(6.6)
Geometry and spatial reasoning. The student uses geometric vocabulary to describe
angles, polygons, and circles. The student is expected to:
(C) describe the relationship between radius, diameter, and circumference of a circle.
Brief Summary: When Sir Cumference finds himself in pain and drinks a potion that his son,
Radius, gave him as a cure, he instantly turns into a fire-breathing dragon! Radius is left with the
task of solving the magic number from a poem on a potion flask in order to give his father to
correct dosage and turn his father back to a human. This fictional narrative of how pi came to
existence is enlightening and includes illustrations of Radius’ thinking process and
measurements of various circular items as he brainstormed the relationship between
circumference and diameter. With the help of friends that allow him to observe their hard work
with pie crusts and wheels, Radius discovers the magic number and saves his father from a life as
a dragon! Radius is honored by his father and friends for his remarkable discovery of pi!
Materials needed:
Pipe cleaners, various circular objects (lids, plates, coins, etc.), rulers, scissors, calculators,
handouts, and pencils
Suggested Activity: Discovering Pi
Use the website to observe photographs of three different stages of the activity:
http://faculty.plattsburgh.edu/margaret.campion/seconded/second/Mindy/Mindy.html
Use this website for extensions on discovering pi:
http://www.uen.org/Lessonplan/preview.cgi?LPid=15436
1. Divide the students into groups of four.
2. Each student in the group will choose one of the circular objects on the table (lids, plates,
coins, etc.) and measure the length of the diameter of the circle with their pipe cleaner.
3. Once they have measured the diameter with the pipe cleaner, the student will cut the pipe
cleaner to indicate the length of the diameter.
4. Each student will find the length of the cut piece of pipe cleaner with a ruler and record the
length, in centimeters, on the table provided by the teacher.
5. Each student will take another piece of pipe cleaner and find the circumference of the circle
by surrounding the circle without overlapping.
6. Cut the pipe cleaner in the length of the circumference and measure the length with a ruler.
Record the measurement in centimeters on the table.
7. Each student will take their diameter pipe cleaner and find a starting point somewhere on the
circle.
8. At the end of the piece of pipe cleaner, hold the place of the ending point with a finger and
continue surrounding the circle until you have traced the entire circle, without overlapping.
9. Record the number of times the diameter surrounded the circumference in the table.
10. Create a number sentence using the measurements for diameter and circumference in a way
that will equal the number of times the diameter surrounded the circumference. The students
should be creating a number sentence that will approximately equal 3).
11. Explain the value of pi and have a discussion of the relationship of circumference to
diameter of a circle as circumference divided by diameter, as well as circumference being three
times the length of diameter.
12. The students can now divide their circumference by the diameter with a calculator to verify
their approximate value of pi and record the data.
13. Each member of the group can observe each other’s observations and compare findings.
13. They have discovered pi and the ratio for pi!
Table students will use to record data.
DIAMETER
CIRCUMFERENCE
(cm.)
(cm.)
# OF TIMES DIAMETER
SURROUNDED
CIRCUMFERENCE
Number Sentence
Ratio for Pi
___ ÷ ___ = ___
___ / ___ = π
1.
2.
3.
Value of Pi (rounded to nearest whole #)
=
Adapted by Vanessa Garza, 2010