Exploring Circumference With Famous Circles

Objective

Students will determine how the diameter and circumference of circles are related.

The Famous Circles

Here are links to the five circles on Google maps. Print them out to measure.

• Place Charles de Gaulle in Paris
• Stonehenge in England
• The circle around Mickey Mouse & Walt Disney at Disneyland in California
• Columbus Circle in New York
• Copernicus Lunar Crater on The Moon

Or, I put them all into one PDF if Google Maps is giving you trouble.

There are purposefully "circles within circles" so students can interpret which circle is really the real circle to measure.

Steps

1. First, students make a guess about how many times they'd need to go across a circle in order to equal the distance around.
2. Next, they'll measure across printouts of famous circles.
3. Then, using string, they'll measure around.
4. Now, students will look for a relationship between the diameter and circumference.
5. We reveal that the relationship is π.
6. I explain a bit more about π.

Resources

• The worksheet (PDF)
• The worksheet (Google Slides)
• A PDF of the Circles