Five Minute Math- Circle Races and Circumference, an Easy and Fun Family Math Activity

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When I was teaching public school, my students always struggled with circle math (finding the radius, diameter, circumference, and area). Circumference, especially, was difficult. Why? If I had to guess, it’s because the distance around a circle is just so hard visualize.

That’s why I designed this week’s five minute math activity to give children a visual for ‘circumference’ in the form of races using their favorite wheeled or round objects.

What you need:

• A large piece of paper (like these)
• Washable paints (I love these Crayola paints– they can even be used for finger painting), you will need at least two different colors
• A variety of difference sized round or wheeled objects- Toy cars, tractors, motorcycles, coins, skateboards, bikes and even balls work great

How to do it:

1. Explain the rules to your child– We will let each circular object turn one time. The item that goes the farthest wins!
2. Let you child pick the object they think will win. Be sure to ask why they think that particular thing will win- don’t offer your opinion, just listen.
3. Prepare your race track- draw a “starting line” on your white paper and collect your paints and paint brushes.
4. Paint a small part of the outside of the circle one color (this will help you tell where each revolution starts and stops) and paint the remainder of the outside a difference color- the diagram above shows how.
5. Invite your child to place the item on the starting line and roll it (in a straight line). Make sure they roll it long enough to have a complete revolution (you should see two of the smaller paint lines).
6. Repeat with the other racers.
7. Look at the lines and declare the line with the longest distance between the two smaller paint lines the winner. If the differences are very small, you made need to measure with a ruler (this is something that is great to do anyway!)
8. Ask your child why they think that particular item won. Again, don’t give your opinion, just listen. Then, invite them to race again, choosing another object.

To expand your child’s vocabulary, you can use the word “circumference” to describe the distance around the outside of a circle. For example, you could explain- “The shape with the longest circumference wins!”.

If your child doesn’t notice it themselves after a few races, you can also point out that the larger the circle, the larger the circumference (and the more likely it is to win the race).

If you tried this activity, we’d love to hear from you! Add a comment to tell us how it went, and don’t forget to subscribe and follow us on social media for more great math activities.