Inform the students that they will be learning about measurements associated
circles. Write the terms circumference, diameter, and radius on the board. Start
these activities by asking the students the definition of these terms. After you
al lowed time for the students to respond, place the definitions of these terms
the overhead. (Transparency 1)
Read the book Sir Cumference and the Dragon of Pi (A
Math Adventure) by
Cindy Neuschwander. Sir Cumference drinks a potion which turns him into a
fire-breathing dragon. His son Radius goes on a quest searching for the magic
number that is the same for all circles which will restore him to his former
With the help of his mother, Lady Di of Ameter, he must “discover” the number
known as pi.
After reading the story to the students, they will
“discover” the number for
themselves. (Attachment 1) Students will measure the circumference and
diameter of various round objects. They will record their data on the table
provided, perform the required calculations, and analyze their results to find
the ratio of the circumference to the diameter is approximately the number .
Activity 2 Build a pi chain with loops of construction paper, each digit represented by
a different color . This activity is a great way for students to visualize what
randomness and irrational numbers mean.
Assign a color to each of the ten digits (0-9). Cut the 10
colors of construction
paper into strips. Display a color/number key in the classroom. (Attachment 2)
Have an official “pi reader” call out the numbers as you
assemble the chain.
As you begin to build the chain, instruct the students to
find the color that relates
to “3”. Explain that they start with three because that is the first digit in
them take a strip of construction paper, roll it into a ring, and tape/staple it
together. They have just begun the Pi Chain! Next, choose a very special 11th
color (perhaps foil paper) to represent the decimal point and discuss its
Ask the class what is the next color they need to use. The next color is the
attributed to “1” since that is the next digit in pi. Repeat the process with
until they can self-pilot through the remaining digits of pi. Once they are
finished, decorate the room with the Pi Chain.
Note: The teacher will need to decide before this activity
is d one how many
digits of pi they would like to assemble into a Pi Chain since goes on forever.
The teacher will also need to decide if this activity will be done as a class
or as a small group activity (a group of 4 or 5 students works the best), where
each small group is responsible for a predetermined part of the Pi Chain. If
groups are used, you will need a “pi supervisor” that is responsible for making
sure the parts of the Pi Chain are assembled in the correct manner.
3 Materials and Resources
• Sir Cumference and the Dragon of Pi (A Math Adventure) book
• Discovering π activity sheet
• measuring tape
• ruler or meter stick
• objects to be measured (juice can, soup can, coffee can, oatmeal box top, cool
whip container top, etc.)
• overhead projector
• construction paper, 10 different colors
• tape or stapler
• color/number key activity sheet
• Digits of activity sheet
Neuschwander, Cindy. Sir Cumference and the Dragon of
Pi (A Math Adventure).
Watertown, MA: Charlesbridge Publishing, Inc., 1999.
Adapted from “The Great Chain of Pi.” Pi Across America. 20 June 2009.
Students will be assessed for their understanding of
radius, and pi from the “Discovering Pi” activity sheet. Students will also be
assessed by monitoring and observing participation when constructing the Pi
“This value, represented by the symbol (pi), has puzzled
mathematicians for nearly four
thousand years, generating more interest, con suming more brainpower , and filling
waste baskets with discarded theories than any other single number…you will
an exact value for π” David Blatner, The Joy of Pi
The circumference of a circle is the distance
around the circle. It is a special perimeter.
The diameter of a circle is any straight line
segment that passes through the center of the
circle and whose endpoints are on the circle.
The radius of a circle is any line segment
from its center to its perimeter. The radius
is half the diameter.
Use the measuring tape or the string and ruler/meter stick
to measure the circumference
of the tops of the objects. Then measure the length of the diameter.
List these measurements in a table like the one below:
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