A. Chain two.
B. Push hook through loop of first chain stitch.
C. Loop yarn around hook and pull through only one loop.
D. Loop yarn around hook and pull through both remaining loops.
E. Push hook through bottom (left) loop from previous operation.
F. Repeat steps C through E until desired length is achieved.

This results in a better chain stitch than the standard one.
The bottom edge of the fabric using this better chain stitch
stretches the same amount as the rest of the fabric. In addition
the bottom edge looks nicer.