The circumference of a circle is the perimeter of a circle.
The radius is the distance from the center of the circle to the circumference,
The diameter is any line that passes through the center of the circle with endpoints lying on the circumference.
Measuring circular objects
In this activity, you are going to find 3 circular objects around the room and measure the circumference and diameter.
Once you have chosen your objects, record the following in the chart:
The object's name.
The diameter of the object.
The circumference of the object.
The result of the circumference of the object divided by the diameter of the object.
Investigate
Consider the following questions once you have completed filling in the downloadable asset.
1.
Compare the division results of your 3 objects. What do you notice or wonder?
2.
Compare the division results of your 3 objects with another classmates results. What do you notice or wonder?
Answer the questions below after you have completed the activity.
Discussion
1.
The ratio that you have discovered is a special number called pi, or \pi. Can you determine a relationship between \pi, circumference, C, and diameter, d?
2.
What about a relationship between \pi, circumference, C, and the radius, r?
Outcomes
7.G.B.4
Know the formulas for the area and circumference of a circle and use them to solve problems; give an informal derivation of the relationship between the circumference and area of a circle.
