First you assemble a 9 patch block. Then you cut it up and rearrange it and sew it back together. It's a very easy way to get a more complicated looking pattern. On the standard D9P, after you assemble it, you cut the block in half both directions. I like to flip flop the opposite corners. I also like to use the same color in the center squares of the 9 patch. It creates a sub pattern and looks great when you do it that way.