Step 4: Stitch this seam leaving an opening of 3" to 4" for turning. Trim 4 corners.
Step 5:Turn the block inside out through the opening. Push the corners out and press. Measure the block from edge to edge. Mine is 10 1/2". This is the size of the batting.
Step 6: Carefully insert the folded batting square through the opening. A pencil should help smooth out the batting making sure it goes to the edges. Stitch the opening closed.