So you've sewn your squares together into 2-patch units. Now combine two of these units to make a 4-patch, making sure a dark patch faces a light patch. If you find your seam does not stay a perfect 1/4" as you're ending your seam - a very common problem - try guiding the fabric with a stiletto.
Your 4-patch should now measure 4 1/2".
At this point, I save my 4-patches until I have quite a stack. I'll decide later what I'm going to do with them. After all, these are not part of my main project, just the leaders, and enders - as some quilters call them.