There's so much for toddlers to learn, and much of it must be learned visually; the sweet, childlike illustrations in this trio of board books help ensure that the ideas resonate with prereaders. In Numbers, one dog plays hide-and-go-seek with two bees, and ten is represented by ten twinkly stars. Opposites contrasts a big elephant with the small bugs scurrying out of his way, and a camel in the hot desert with the polar bear who lives in a cold land, while in Animal Sounds, a monkey chatters, a tiger roars, mice squeak, and an owl says, "Twit twoo." (3 vols., Boxed)