This looks like my quilt in progress Mine is using a jelly roll (2 1/2" strips WOF). Here is how I cut and assembled it
[ATTACH=CONFIG]481292[/ATTACH]
and this is how I put then together
[ATTACH=CONFIG]481294[/ATTACH]
When arranged this way - two rectangles sewn tog are 12 1/2" unfinished or 12" finished. Hope this helps.