Single Crochet in Foundation Chain

      when you crochet a flat piece (like a hat or a scarf), you will see "Row1:Single crochet in 2nd chain from hook" in the pattern, it means we need to do single crochet stitches in to the chain. Now we learn how to do single crochet in a chain.
      Review the chain knowledge covered earlier.

HOW TO COUNT CHAIN STICTHED?
    Each chain stitch makes a ""V"" shape. Count the number of V's to count the number of chain stitches you have.
    It's also important to keep in mind that when you're counting chain stitches, you shouldn't count the slip knot that you made at the beginning of your chain as a chain stitch.
     Here’s a chain with 13 stitches in it. I’ve called out the second chain from the hook, because if you’re making the next row with single crochet stitches, the first stitch you make will be in the second chain from the hook. This is because the chain that you skipped gives the first single crochet stitch its height.

 WORKING INTO THE FOUNDATION CHAIN?

   You may work under one or two strands of chain loops as shown above. Either of these methods forms an even, firm bottom edge.
   You may like to work into the "back bar" on the back of the chain. This forms an even, stretchy bottom edge that is ideal for garments.
   Whichever method of working into the foundation you choose, be consistent. Work all pieces of a project in the same manner.

HOW TO DO SINGLE CROCHET INTO FOUNDATION CHAIN (STEP-BY-STEP WITH PHOTOS)