Cut 4 strips that measure the exact width of your nine-patch blocks, about 6 inches.  From these strips, cut six squares from each.  You'll need 24 squares.

These are the two blocks that form the entire Irish Chain.  Pin and sew one plain block to one patch block, right sides together.  Press the seam to one side.  Add another plain block to the patch block in the same way.  Make eight identical strips, alternating six plain and nine-patch blocks across. Press all of the seams to the same side.