Algebra with shapes

Mr Gregg came across these shapes in Foundation Stage:

They're called Rolf Circle Fun, and they're just right for a bit of algebra...

We used this blank sheet:

and, with Paint, coloured in sections. (Only the Rolf shapes were allowed.)

Next we named some areas of the shape: a b c 

We could see quite quickly that b + c = a
So, armed with this, we were able to start describing all the areas in our designs with abcs. Like this:

Here's a slideshow of some of our creations: