Big Fat Hen

Increasing numbers of newly hatched chicks buckle a shoe, shut the door, pick up sticks and lay them straight in this ebullient version of ``One, Two, Buckle My Shoe.'' Baker's ( Elephants Aloft ) bold outlines, plump figures and vibrant acrylics add up to an especially appealing counting primer for children just old enough to have learned the familiar rhyme. The big fat hen herself is enormous and grand, a stately splash of emerald covering most of a two-page spread. She and her several hen friends have friendly, even merry miens that exude reassurance and warmth; distinguished from one another by plumage color and pattern, as a group they have the sparkle of a cluster of gems. Additional creatures--three worms, five snails, seven bees--carry out the counting theme on a smaller scale, providing fresh interest for the frequent rereadings that are sure to ensue. Ages 2-6. Children's BOMC main selection. (Mar.)