This semi-circular, half-pi shawl is based on Elizabeth Zimmerman’s original numbers for her round, pi shawl design. Most often, a full circle shawl is folded in half before wearing; with a semi-circle, there’s no folding, so the lace stitch patterns remain distinct as they’re not layered over each other. This design features four lace stitch patterns, each one four stitches wider than the previous one—hence the name, “Plus Four.” Plus fours were once popular sports attire on the golf course, so I’ve knit my sample in a lovely, rich shade of green.