You start with strips that are 2-1/2" wide. A jelly roll is perfect. Pair a light and dark (anything with some contrast works) right sides together. I cut 2 strip sets that are 16-1/2" long; I also cut one 2-1/2" square from the dark.
Your strip set should measure 8-1/2"
You will now sub-cut this set into 2-1/2" strips. You'll cut 6 of them:
Rearrange alternating the light / dark in the left corner. You're going to sew 5 of these together
Sew the extra 2-1/2" dark square to the end of the 6th strip set.
You can now sew the 6th strip set to the others already sewn together making sure your order is light-dark throughout.
If you are careful, you can nest the seams.
Your block should measure 10-1/2" unf
I'll post the picture of the finished product in the next two days, after I get back to California
Happy New Year!! Here's to a very healthy and productive 2015!