ktbb

I agree...and to do this you can cut a square and a triangle, then stitch them together..make as many of these as you need to do the length/width...stitch these together by matching the seam between square/triangle on one pair with the outside edge of the square on the adjacent pair...these will then form your long piece to stitch to your straight edge quilt body. Your long piece with square/triangle sets will begin with only a triangle and end with only a square...you'll see how it fits once you put a couple together. To finish the edges, I'd sandiwich it with the backing which is larger than the front, pin it well, then stitch around the perimeter using the raw edges of the squares to determine the seams (of course leaving space to turn it right side out)...trim off the backing only after the stitching is done...and clip seams on the inside corners so it turns nicely.

and the red plaid looks like prairie points