The sections between “ribs” are done in garter stitch. The sleeves are worked in the round. The sweater is worked top-down and there are no seams to do at all. :) The hat is also worked in the round and is worked bottom up.

The 0-3 mos size uses #4 & #6 needles and the 3-6 mos size uses #5 & #7 needles.