We start with a 4 by 8 foot sheet of plywood. As the signs are to be 2 feet long, we divide 8 feet by 2 feet, obtaining 4 pieces of dimensions 2 feet by 4 feet.
We'll then cut four 2 foot by 1 foot pieces from each of those four 2 foot by 4 foot pieces; we end up with 16 pieces of size 1 by 2 feet.