I need help squaring up a block that is larger than any square I have in my notions....I know there must be a way to do it. Can someone please help my old brain. I need an easy explanation. My blocks are 20 1/2 inches square (I did the ten minute block and made 20 of them.) My granddaughter and I are sewing together on separate machines and in putting the blocks together I notice they aren't all square, so before going any farther I want to check the blocks. And then once they are sewed together I must check again, right? This is the part I hate cuz I just can't get them square, no matter what I try.