Let’s see how to work right-side rows.

Hold the yarn behind your work. Insert the right needle into the back of the next stitch on the left needle.

Wrap the yarn as for a normal knit stitch.

Pull the yarn through to the front.

Slip the stitch off the left needle.

Work a regular purl stitch.

Let’s see how to work wrong-side rows: work a regular knit stitch.

Hold the yarn in front of the work. Insert the right needle into the back of the next stitch from left to right.

Wrap the yarn and pull it through.

Slip the stitch off the needle.

On the right-side of half-twisted rib, the knit stitches are twisted.