Ok, I have made some of these and I will try to explain (hope it won't be too confusing:)). Say, you want a 6 inch total. Cut squares 2 1/2 inches (this is for the solid squares - the background and the centre of the star) for the other squares (the bi-coloured units) cut them 2 7/8 inches. When stitching the bi-coloured units be sure and keep a really accurate 1/4 inch seam. I learned this technique from a really useful book "Scrap Quilt Sensation" by Katharine Guerrier.