Hat and Scarf in Checkerboard Pattern

How to knit a hat and scarf in checkerboard pattern:
Hat size: S.
Scarf size: 18 cm × 108 cm.

Materials:
350 g yarn (100% wool; 150 m/50 g); knitting needles size 3 (US 2½ / UK 11); 20 rhinestones.

Stockinette Stitch: knit on right side, purl on wrong side.
Checkerboard Pattern:
Rows 1, 3, 5: * 12 knit stitches, 12 purl stitches *, repeat from * to *.
Row 2 and all following even rows: work the stitches as they appear.
Rows 7, 9, 11: * 12 purl stitches, 12 knit stitches *, repeat from * to *.
Repeat Rows 1–12 throughout.

Gauge:
In checkerboard pattern with yarn held double: 26 stitches and 28 rows = 10 × 10 cm (4 × 4 in).
Hat
Headband:
Cast on 18 stitches and work 110 rows in stockinette stitch, then bind off all stitches.
Fold the strip lengthwise with the seam facing outwards.
Pick up 144 stitches along the upper edge of the headband and work 60 rows in checkerboard pattern.
Starting from Row 37, decrease 1 stitch in each square, then in each square decrease 1 stitch every 2nd row 10 more times = 12 stitches.
In Row 61, draw all stitches together with the working yarn.
Evenly sew on the rhinestones.
Finishing:
Sew the seam.
Make a large pompom and attach it to the top of the hat.
Scarf
Cast on 38 stitches, work 288 rows in checkerboard pattern, and bind off all stitches.
Make 10 pompoms and decorate the scarf with them.