Roll right along with an informative lesson that makes cents. Scholars learn that some shapes roll without any change in its width. The video in the Numberphile "Coins" series starts with two-dimensional figures, such as Reuleaux triangles and British 50 pence coins, and then continues on to three-dimensional shapes, such as Meissner tetrahedra.

Concepts

2-d shapes, 3-d figures, width

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Additional Tags

math

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Instructional Ideas

• Team up with a technology teacher and have learners cut out Reuleaux triangles
• If available, have samples of shapes or solids of constant width available for pupils to play with
  

Classroom Considerations

• Individuals need to understand how circles and spheres have a constant diameter
  

• This video is hosted on YouTube

Pros

• Narrator's antics provide some comic moments
• Video is interesting and informative
  

Cons

• None