Then worked single chains up one side and without working any increases, single crocheted down the other side.
Then kept working around, single crocheting in the back loop of each stitch like this:
By the way, I also finished the 2 Doctor Who scarves I was knitting for my friend's kids for Christmas. One is 12 feet and the other about 14 but they'll stretch. So blinking adorable! I lived doing then so much that I've got the yarn to do one for myself now!!