I used a whole lot of different machine embroidery stitches.
I don't think I've ever shown the back of one of these study squares. Here's what it looks like, a big thready mess. The fabric I used this time for the backing is the printed instructions for making a holiday decoration that I completed probably twenty years ago. It was in my scrap bin and was the right size to cut up and use. I write the week and the date also to help me keep track of these quiltlets.