What caused the extra rotation? Class members visualize a coin rolling around the circumference of another coin. They determine the reason the rolling coin rotates twice. Further questions require them to determine a generalized formula to find the number of rotations based upon the size of the stationary coin.

Concepts

circumference, circles, rolling, coins, rotations

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Additional Tags

math

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Instructional Ideas

• Demonstrate rolling the coins to the entire class and ask individuals to explain
• Have pupils work in pairs with their own set of two coins and then explain to the class how they arrived at their solutions

Classroom Considerations

• It is beneficial if the class knows how to work with circumferences and rotations about a point

Pros

• Question includes a picture to help visualize the orientation of the coins
• Answer key provides a detailed explanation of the correct solution

Cons

• None