1.)Explain that students will be learning about measuring circles and a mysterious number called "pi". Define the terms circumference, radius and diameter. Read the book Sir Cumference and the Dragon of Pi to the class.
Card catalog description:
When Sir Cumference drinks a potion which turns him into a dragon, his son Radius searches for the magic number known as pi which will restore him to his former shape.)
2.)Divide students into groups of 2-3. Using tape measures, instruct the groups to measure the circumference and diameter of the circular objects they have been given. (Another option that may be easier for students is to use string to measure around the objects and then measure the length of the string with a ruler.) Remind them to measure CAREFULLY!
3.)Allow students to work on their own. Monitor the room for questions and to make sure the students measure correctly.
4.)Together the class should record the groups' measurements in a table. Then using calculators, divide (circumference/diameter) and record their findings to the hundredths place. (OPTIONAL: Use a spreadsheet program to record and calculate the measurements. See attached table to use or adapt for use.)
5.)Ask students to look for any pattern in the results. They should notice that circumference/diameter is always around 3.14. Explain that this number is called "pi". Assign students to computer stations and have them explore the history of pi. After students have been given adequate time to explore the site discuss the information as a group. What did they find most interesting? How far do they think they can calculate pi?
6.)(If a phone is available for student use at school this portion of the lesson can be completed during class time. If not, assign this step for homework.) Tell students that they can use what they have learned to find out which local pizza restaurants offer the most pizza for the least amount of money. Allow students to call predetermined local pizza restaurants and ask for pricing on small, medium and large cheese pizzas. They also need to find out how many inches each size pizza is. Students should record this information for later use.
7.)Review the definition of radius. Tell students that they can use the pizza measurements to determine the radius (diameter/2). Next explain that the formula to find the area of a circle is Area=Pi x radius x radius. Instruct students to find the radius of their pizzas and record their findings.
8.)Next students will divide the cost of the pizza by the area of the pizza to get cost per square inch. Students should do this for each size and record their findings on the chart or table. Findings should be compared to determine the best pizza value for the money.
9.)As a fun culminating activity visit the site below and let students sing along to the "Digit Connection".
(The Digit Connection
)A song about pi to the tune of "The Rainbow Connection"