Square Corners

Have a look at the three grids below.

What do you see?
What do you notice?

        

Once you have had chance to think, talk to someone else about your noticings.

Click below to read what some children noticed.

Miles said:

Freya said:

Omar said:

Do you agree with Miles, Freya and Omar? Why or why not?

Now it is your turn...

Use the interactivity below to put blue counters on the grid.
Your challenge is to put as many counters on the grid as you can but none of them must lie at the corners of a square. 

How many counters can you use without making a square? 
How do you know that you cannot have more counters?

If you would prefer to work away from the computer, you might like to use a printable sheet (square grid or array of circles) with counters.

We would love to hear how you are going about this task!

This problem is taken from 'Mathematical Challenges for Able Pupils Key Stages 1 and 2', published by DfES.