# Activities

• • • ##### Subject Area

• Math: Geometry: Circles
• Math: Statistics: Inferential Statistics

• ##### Author 9-12

60 Minutes

• ##### Device
• TI-30X IIB
• TI-30X IIS
• TI-34 II Explorer Plus™
• ##### Other Materials
This is Activity 15 from the EXPLORATIONS Book:
Math Investigations with the TI-30X IIS: Activities for Secondary Mathematics

The following materials are needed for this activity:
• String
• Ruler
• Graph paper
• Spaghetti
• Glue
• Several round objects of various sizes
• Cardboard paper towel tube and an oatmeal box
• ##### Report an Issue

Looking at Statistics Through Circles

#### Activity Overview

Students will measure round objects to determine the circumference and diameter, and use the data to explore geometric concepts of the circle with statistics.

#### Before the Activity

• See the attached PDF file for detailed instructions for this activity
• Print pages 148 - 149 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to the class.

• Measure the diameter and circumference for each round item and record the values in a table
• Explore the relationship between the circumference and diameter
• Observe that the ratio of circumference to the diameter is the same for all round items
• Plot the circumference versus diameter data
• Draw a best-fit line and determine its slope
• Measure the diameter of the cardboard paper towel tube
• Use the graph to estimate the tube's circumference
• Use the calculator to find an equation for the line
• Use this equation to predict the circumference of the tube
• Measure the circumference of the tube and compare it with the prediction and the estimate
• Similarly, determine the measure of the diameter of the oatmeal box
• #### After the Activity

Students complete the Student Activity pages.

• Review student results
• As a class, discuss questions that appeared to be more challenging
• Re-teach concepts as necessary