Module 3
1. Module 3
1.8. Page 3
Module 3: Linear Measure
Explore
You will explore the relationships between the radius, diameter, and circumference of a circle.
Try This
Work with a partner.
Complete the following table using at least five circular objects, such as jar lids or cans. Make sure that all of your objects are different sizes.
Step 1: Using a tape measure or a ruler, measure, to the nearest millimetre, the diameter and radius of each object. Trace around each object, and use paper folding as described in the Get Started section. Use a separate blank sheet of paper for each object.
Step 2: Determine the circumference by carefully wrapping a length of string around the object. Cut the string to match the circumference as precisely as you can. Then lay the cut length of string along your ruler or tape measure to measure the string.
Step 3: Enter your measurements in the table.
TT 1. Use your calculator to determine the ratio 
correct to one decimal place.
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Object |
Radius (mm) |
Diameter (mm) |
Circumference (mm) |
Circumference Diameter |
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Step 4: Answer TT 2, TT 3, and TT 4. Then tape each string to its corresponding tracing, label each tracing, and place the papers in your course folder.
TT 2. For each object, how many times longer is the diameter than the corresponding radius? Explain your answer.
TT 3. About how many times is the circumference of each object longer than the object’s diameter?
View the video “Unrolling a Circle” to help you answer this question.
TT 4. Does the size of the circle affect the ratio,? Explain your answer.
Share
Post your answers to TT 1–TT 4 in the discussion area or share them with your partner.
You may add the responses of other students to your data so that you have additional rows of information to make conclusions about the ratio, .
Discuss the effect of circle size on the value of this ratio. Use your data to back up your thinking.
Write the final version of your answers to the Try This questions, and place a copy of your answers in your course folder.