How to knit plaid with crochet stitches

In this DROPS video we show how we can subsequently work through a knitting piece by crocheting chain stitches through the knitting piece to make checkered patterns.
We have already knitted a test piece where we have worked: knit 3, purl 1, knit 3, purl 1, knit 3 + garter stitch in each side, another color (grey) in every 6th row and we have already crocheted chain stitches in one field with purl stitches.
Insert the hook through the work (where you want the vertical strip to begin) and pick up the thread, skip 1 purl stitch, and insert the hook back into work (if desired, crochet also in each purl stitch), pull the thread and pull it through the work and the loop on the hook. Repeat as long as you want the vertical strip to be.

We use the yarn DROPS Snow in the video.