1/2" striped square.  Just remember when you are sewing to have the piece with the marked 1/4" point on top sew you can see it! With right sides together, and starting at the 1/4" mark , sew the striped square and the brown trapezoid together, stopping at the 1/4" mark and securing the first and last stitch. With right sides together pin one white trapezoid to one side of the striped square, folding back the brown trapezoid to keep it out of the seam and so you can align the corners of the white trapezoid and the striped square.  You will be able to feel the bulk of the brown/striped seam with your fingers and this should align itself nicely with the 1/4" mark you previously made on the white trapezoid.  Sew together, starting at the 1/4" mark and stopping at the 1/4" mark and securing the first and last stitch. I often stop and start one thread from the 1/4" mark (on the seam side) just to allow a little extra room for the thread. Repeat for the other white trapezoid. 4.     The last step is to sew the white and brown trapezoid angled sides together.  You will often find this step and the last step combined - that is sewing this step and the white trapezoide/striped square step as one long seam with a pivot at the end of the angled part.  That way is faster, of course, but I find the accuracy of that a little unsatisfactory