Hello, I have just finished making 36 blocks for a quilt that I found the pattern for in a magazine. It is from Quilters World April 2009, the Blue Betty. The instructions say they are to be 12x12. I am uncertain how to square these up before putting them together. Do I take my 12x12 ruler and make them exactly 12x12 or do I add the 1/4 inch to each side making them 12 1/4 each side for the seam allowance. I am a fairly new quilter and I am also unsure how to "square" up. I have a square ruler, 12 1/2 x 12x 1/2. Do I just take a little off each side until the block measures 12X12? Thank you for any help you can give me.