Poly plug pattern

Create a pattern on the small grid. How could you extend your pattern on the larger grid?

Problem

Can you create a pattern on a 5 by 5 board like the one below? 

Image
A 5-by-5 pattern of red circles arranged in a square.

You could print off this board and use counters to create a pattern.

 

How could you continue the pattern on a large 25 by 25 board like this one? 

 

Image
A 25-by-25 square of red circles. The 5-by-5 square in the top left is highlighted.

You could print off this sheet to try out your ideas.

We would love to see pictures of your 5 by 5 pattern and your extended pattern.  We would also be keen to hear how you went about extending it.