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:

Mr Euler's formula

F + V - E = 2

This is the formula that Mr Euler came up with for 3D shapes.

It means

Faces + Vertices - Edges = 2

Today we tried it out. It was true for all the shapes we tried.

But Jacques and Clara came up with a shape it doesn't work for: the sphere. Here, 1 + 0  - 0 doesn't equal 2.

Making geostrips

Today we made our own geostrips of regular and irregular shapes.

Which shapes can you see?

How many different types of angles can you name?

Investigating hexagons

We have been making hexagons using geostrips.  Whilst a regular hexagon can be changed in size and can be inverted, we found that irregular hexagons are much more interesting! 

Have a look...

The photo above shows an example of an inverted hexagon (its sides have been pushed inwards).

Here we are concentrating on finding out more about irregular hexagons: