If you are trying to match up batting to use iron on batting tape or sew together use a zig zag stitch, it can make you go crazy trying to line up the edges smooth,straight and flat. Layer both pieces on top of each other making sure that there is overhang from both pieces. Place your ruler overtop, and cutting mat underneath, line up your ruler and trim both pieces. Unfold and place both pieces together and line them up, iron the batting tape on or sew together easily with now straight edges.