The new £1 coin

Based on the old threepenny bit and with a number of features to prevent forgery, today sees the launch of the new 12-sided £1 coin.

For some businesses, its introduction has caused a lot of work ensuring things like shopping trolleys and gym lockers are ready to accept the new legal tender. The coin must have a constant width in order for that to happen, which reminds me of the great ‘shapes of constant width’ resource in National STEM Learning Centre the resource collection:

Each of the shapes in the pack, from Maths Gear, have the exact same diameter whichever direction you measure them in- just like the 20p and 50p coins (allowing vending machines to recognise each coin regardless of how you put it in the machine)- the shapes in the Maths Gear packs are based on an equilateral triangle, a regular pentagon, a 3,4,5 triangle and an irregular pentagon.

To explore shapes with constant width further, see this Numberphile video.

As a result, you might be inspired to get your students to construct their own shapes of constant width using just a ruler, pencil and pair of compasses- just like in this Carom Maths resource:

For more construction and loci teaching ideas, click here:

More on the new coin can be found in this BBC news video.


Age11-14, 14-16, 16-19
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