This step uses the units from step 2. We will take those units and sew them to focus fabric half square triangles to make 3 1/2 " squares. If you are making the small quilt you will need a total of 48 squares when you are done, for the larger quilt you will need 100.
I used 3 1/2" strips and cut my half square triangles from them using my tri-recs ruler that I have used in previous steps. Or, you could cut 4 1/4" squares and slice them in half diagonally.
Place the unit from step 2 right sides together with the half square triangle and sew a quarter inch seam along the long side of the triangles as shown in the photo above. Press open with seams toward the triangle that was just added. Trim the square to 3 1/2" if needed. The units from step 2 should need to be trimmed as they were a bit oversize to accommodate for variations in piecing and pressing techniques. As long as your finished block is 3 1/2" square, you are fine.
Enjoy every stitch!