This is normally something children do in secondary school, but we got some idea of what it was all about.
In the picture there's a right angle triangle. We know two of the sides - in this case the shorter sides are 3 long and 4 long. We want to find out the length of the longs side.
Here's Rozenn explaining it:
And here are the Cuisenaire rods we used to help understand it better:
Mr Gregg was particularly pleased that Rozenn learnt about this because it's one of his favourite bits of mathematics!