Block 81

This week's block is a fun one.  And by the end of it, you'll be an expert with the square-in-a-square. 

Here is everything set out and ready to go.

Here I've started on the 4-patch in the centre.  Plus the corner triangles. 

Here the two sets of corner triangles completed.  The centre 4-patch is done and the first square-in-a-square has been completed. 

And now the square-in-a-squareathon begins.

And continues....

And continues, until you end up with the finished block.