OK, I'm assuming that you are ready to rock and roll!!
Get your strips out, here we go.
Step 1: Take your hearth and your smallest piece - both measure 2.5".
Right sides together, pin the small piece on at each end, making sure the edges line up.
Its really important to keep an eye on your pieces and the length. If you are working inaccurately (or your strips were cut poorly) your block will get more and more out of proportion. Your next piece wont line up on the edges, and you'll introduce a skew. You can't fix this by chopping off the uneven end. You have to go back and fix your mistake to ensure your block stays square.
IF YOU MAKE A MISTAKE..............................
So you have made a booboo - want to see one of mine?
In this case I pinned too far away from the edge. At some point you need to use 3 pins with this block, and I was being lazy. The fabric shifted as I got to the end, and the blue piece moved inwards. Worst place for it to happen - specially when you start doing small triangles in your blocks!
So to fix this , I used my unpick and picked back as far as I needed to in order to realign the pieces.
I put the block back on to my sewing machine, and started back an inch or two from where I had unpicked to.
Sewing more carefully this time (with my tongue sticking out of course) I resewed the partial seam, overlapping the good sewing and merging into the new seam. I am totally confident this will hold, it won't look odd ironing because I did a clean overlap, and it saved me a couple of minutes.
So if you have done everything right, you can measure your completed block, and it should measure 12.5" by 12.5". If its a bit more, your seam allowance is too small, if its smaller than 12.5", your seam allowance is too large.
Voila!! You have finished the first block of your sampler. Now the tough decision.... Do you make more of these? Or do you sit back and wait for next month. It is such a quick easy block, and a brilliant stash buster, I reckon you might want to crack on with a few more this month. And if you make any you don't want to use, lets put them all together and make a charity quilt - as long as they measure 12.5".......