Groove is in the Chart is pattern #45 in the 2018 Harmony Blanket Knit Along. The ridges and valleys in this square look like textured stripes from the top, but when viewed at an angle, a hidden image appears! This remarkably easy technique is called illusion knitting or shadow knitting and uses just the basic knit and purl stitches.  The pattern includes both written and charted versions of the instructions.