## Equipment needed

Card, rulers, compasses, scissors.

## Curriculum Topics Covered

Construction with compasses, geometrical reasoning.

**More Details**

Activities include:

-Explore what 'constant width' means with a simple practical investigation (use **Shapes of constant width** worksheet, **Shapes to cut out** printed on card, scissors and scrap card for parallel sides).

-Use geometrical reasoning to prove some shapes based on an equilateral triangle are not of constant width (**Shapes of constant width** worksheet). Can you now create and construct your own shape based on an equilateral triangle that *is* a shape of constant width? (Use **Triangles for construction** sheet).

-Learn how to construct the Reuleaux Triangle and other shapes of constant width including those based around an irregular polygon, and 20p and 50p coins that are both shapes of constant width! (**Constructing shapes of constant width** sheets).

To find out more about shapes of constant width watch the Numberphile video with Steve Mould featured below, and a video by Steve Mould and Matt Parker on the Maths Gear YouTube channel: https://www.youtube.com/watch?v=pvRQMDUsE3k

A set of four shapes of constant width can be purchased on the Maths Gear website at https://mathsgear.co.uk/collections/shapes/products/shapes-of-constant-width-in-acrylic-set-of-4