 Investigation: Creating circle graphs

Lesson

Sierra and Raoul did a survey of their class of $20$20 students about their favorite pie flavor. Most of the results are below.

Flavor Number of students
Pecan $8$8
Blueberry $5$5
Peach $4$4
Key Lime $2$2
Coconut cream
TOTAL $20$20

Activity

With a partner, work through the questions below. Show your teacher your circle graph when you are done.

1. How many students' favorite pie flavor is Coconut Cream? How did you figure this out?
2. How many different categories of pie flavors did Sierra and Raoul collect?
3. What flavor was the most popular?
4. If we were to make a circle graph, how would the sizes of the sectors of Pecan and Peach compare?
5. If we were to make a circle graph, how would the sizes of the sectors of Pecan and Key Lime compare?
6. If we were to make a circle graph, which segment would be the smallest? largest?
7. What fraction of the circle will each segment take up? Fill in the table below, the first row is done for you.
Flavor Number of students Fraction of students
(out of 20)
Fraction of students
(simplified)
Pecan $8$8 $\frac{8}{20}$820 $\frac{2}{5}$25
Blueberry $5$5
Peach $4$4
Key Lime $2$2
Coconut cream
TOTAL $20$20
8. Let's make a circle graph! We will use the GeoGebra applet below to help us.

Applet Instructions:

1. Use the slider to select the correct number of categories (question 2)
2. Check the box for revealing the fractions
3. Slide the new slider to the common denominator
4. Use the blue points on the circle to slide to make the segments the correct size
5. Uncheck the box to remove the fractions
6. Show your teacher - be sure to explain which segment is which
 Created with Geogebra

Further discussion questions

1. Consider a survey question that you might be interested in learning the results of. What categories would you have? How many people would you ask? If you have time, conduct the survey and create a circle graph to show the results.
2. What are the benefits of using a circle graph over a table of data?
3. What are the drawbacks of using a circle graph over a table of data?
4. What if you had a table of data as shown below. Explain in detail how you would create the circle graph, then create it using the applet above or using colored pencils and paper.
Eye color Number of people
Blue $24$24
Green $18$18
Hazel $6$6
Brown $30$30
TOTAL $78$78

Outcomes

6.10a

Given a practical situation, represent data in a circle graph