1. Use a pencil to mark a diagonal line on wrong side of each red print 4-7/8" square and on 11 assorted light blue, gray, pink, and green print 4-7/8" squares. (To prevent fabric from stretching as you draw lines, place 220-grit sandpaper under each square.)
2. Layer a marked red print square atop an unmarked light blue, gray, pink, or green print 4-7/8" square. Sew together with two seams, stitching 1/4" on each side of marked line (Diagram 1). Cut apart on drawn line to make two triangle units. Press each triangle unit open, pressing seam toward darker fabric, to make two red triangle-squares. Each should be 4-1/2" square including seam allowances. Repeat to make six red triangle-squares total.
3. Using marked assorted print squares and remaining unmarked light blue, gray, pink, and green print squares, repeat Step 2 to make 22 assorted triangle-squares total.