Beginning a Bonus Quilt
I keep a stack of these light and dark 2 1/2" squares next to my sewing machine. At the beginning of my sewing session, I take two squares,a light and a dark, place them right sides together, and sew these with a 1/4" seam allowance to warm up my machine and I. It will let me know if my machine wasn't threaded properly, I can check my 1/4" seam allowance, thread tension, and make sure my fabric doesn't get caught in the throat plate when I start sewing my actual project. I also end my sewing session with two squares, right sides together, and leave those under the presser foot, ready for my next batch of sewing. When you're chain-piecing, it actually saves thread as well!
Some quilters use throw-away scraps for this system, but why waste any of your sewing efforts? Collect the two-patches for a while, and when that stack becomes too large, make them into 4-patches! And before you know it, you'll have the beginning of a Bonus Quilt!