1. For one block, gather two 12" squares and one 11-5⁄8" square from the same small print and two 12" squares and four 11-5⁄8" squares from the same large print.
2. Use a pencil to draw a diagonal line on wrong side of each small print 12" square.
3. Layer a marked square atop a large print 12" square. Sew together with two seams, stitching 1/4" on each side of drawn line (Diagram 1).
4. Cut pair apart on drawn line to make two triangle units. Press each triangle unit open, pressing seam toward darker print, to make two triangle-squares. Each triangle-square should be 11-5⁄8" square including seam allowances.
5. Repeat steps 3 and 4 with remaining marked small print square and remaining large print square to make four triangle-squares total.
6. Referring to Diagram 2, sew together triangle-squares, large print 11-5⁄8" squares, and small print 11-5⁄8" square in three rows. Press seams toward print squares. Join rows to make a Shoo Fly block; press seams away from center row. The block should be 33-7⁄8" square including seam allowances.
7. Repeat steps 1–6 to make four Shoo Fly blocks total.