I'm doing this one for a baby. It will be large enough to use as a crib blanket.
I used Caron Simply Soft yarn and a size H hook. That's 5mm for the hook and worsted weight. Your brand may have a 4 on the label next to weight.
For the foundation chain, with White(MC) ch 163.
Row 1: (shell stitch row) Work 1 dc in 5th ch from hook, 3dc in next ch, dc in next ch,* skip next 2 ch, (dc in next ch) rep from * across to end of ch. There will be one ch loop extra at end. We'll use it later.
You are going to drop the loop from the hook for now. I want you to pull the yarn so that it makes a very large loop. This way you won't lose any of your work.
Do not turn.