Here’s a step-by-step guide to the extended single crochet stitch, as used in my Granite Stitch Scarf. The extended single crochet (esc) is just like the single crochet stitch with an extra step.
1) Insert your hook into stitch and yarn over (just like you would start a single crochet)
2. Draw yarn up through stitch, there are now 2 loops on the hook. (still like single crochet)
4. Yarn over and pull through both stitches
I used a big hook for clarity, so the finished stitch won’t be this loose if you use the proper hook for your yarn.
Now if you’re alternating between esc’s and ch-1’s, like in my pattern, the next step is to chain 1, skip 1 stitch, and esc in the next — continuing until the end of the row.
In this pattern, you always start and finish your row with an extended single crochet, so on the next row (i.e. row 3 of the pattern and all odd rows) you will have 2 esc’s at the start before chaining. In the picture below, the first esc has been done and the black arrows indicate the chain-spaces where the extended single crochet stitches go into.
After a few rows, this is what it should start to look like. Notice that the esc stitches are offset, like mesh, or a checkerboard pattern.
Please let me know if you have any questions or if anything is unclear.