So we left off with the sashing or "grout" fabric attached, front and back, to a single quilt block. Now we being the process of marrying up more blocks.
With backing side up, lay out your second block in the strip. Matching at top and bottom, lay your first block, with sashing attached, on top. Open up the bottom strip of sashing and match it's unfinished edge to that of the block on the bottom.
Pin the heck out of it.
This is super-awkward to sew, as the sashing seam from the top always wants to get in the way, but with a finger guiding it and a little bit of persistence, you should be able to accpmplish something pretty close to 1/4 inch seam.
This is the magic moment, when you unfold your project and realize what you have. Here's the innards of the join, where your two 1/4 inch seams should snuggle up against each other sweetly. (Some quilters sew along this seam with a zig-zag stitch, though I never have. This zig-zag would, of course, show on the bottom though not the top.)
This is the folded sashing from the top, brought over to show you how sweetly this seam finishes off.
This is a view of the bottom of the quilt, where the unfolded sashing has now joined the two squares. Only one more step remains...
A pretty decorative stitch, if you please, or even a careful seam along the sashing, one or two threads from the edge, to secure the folded sashing in place along the quilt top. As this quilt is a crazy quilt, a decorative stitch suited the project just fine.
Repeat, and repeat, and repeat... make strips of quilt that will in turn be joined with the same techniques! Borders, if desired, can be attached this way too.