How do you knit a flat seam?
To create a flat seam, you hold the two knitted pieces together with right sides facing and work at the very edge of the work. You move the needles through the fabric from the front to the back and then from the back to the front to create running stitches.
What is a Backstitch seam in knitting?
When you join knitted pieces by using backstitch, you sew them together in the conventional manner. Backstitch involves placing the right sides of your pieces together and moving your tapestry needle in and out along the seam line.