Originally Posted by
Tartan
When you sew the pairs together to form the 4 patch, the top seam allowance should point towards the needle and the bottom seam allowance down. You may need to hold the top allowance with a pin so the foot doesn’t catch on it as you sew over it. This makes the intersections lock together when you sew for a nice match in the center.
She said the seams were going in opposite directions; so pressed open. I think the only way to get pressed open seams to line up perfectly would be to pin every time. It's so much easier to line up seams pressed to one side while nesting them. If the top seam is pressed away from you, as Tartan said, they snug right up as they go into the needle. A wooden skewer or awl of some sort helps to tuck that seam allowance under the presser foot.