Unfortunately, the directions for this step are even more inadequate. You are supposed to line up the 45 degree diagonal line on a square ruler with the center of the narrow white strip then trim to 6.75 inches square. There aren't any instructions regarding how to ensure the block is centered and you don't cut too much from one side. I was going to use my Tucker Trimmer ruler but it uses half inch increments, without markings for 6.75 inches.
I ended up using my 8 inch square ruler, adding a piece of tape to mark the mid-line for a 6.75 inch square. Below is the block after trimming.
Four of these pieces are sewn together to make a full block, below.
A little unsewing was involved in making this first block, in an effort to get all the pieces lined up and the corners matched, etc. But I think I have the process down now and the rest should go more smoothly. Now that I'm this far along, I can see how a similar effect could be achieved using a different, easier constuction method, but it is too late to switch now.
Despite all my whining about the poor instructions, I like the design and am happy with the fabrics I put together. It will add another fresh, modern quilt to my Christmas quilt collection.