Ages 14 and over
Design your own gold coins that are worth different amounts of money. The only rule is that the measurements must be precise because gold is expensive and, if lots of the coins are to be minted, they need to contain the exact quantity of gold.
Pupils can find the up-to-the-minute price of gold per gram at www.lbma.org.uk statistics_current.htm, or the teacher can check that morning. It could be interesting to talk about why the price varies whereas other relevant factors, such as the density (19.3 gcm3), are fixed.
Questions learners might discuss could include:
1. What denominations are possibledesirable?
2. How thick should coins be?
3. What shape is best?
4. Why aren't coins made out of gold any more?
Able pupils might design coins consisting of two different components (eg, gold and silver), like the UK pound;2 coin, or coins with holes in the middle. Making a coin in the shape of the UK 50p piece is a significant challenge for a GCSE pupil with a knowledge of trigonometry and sectors of circles
Colin Foster teaches mathematics at King Henry VIII School in Coventry