Peek-A-Boo What? (Begin Smart) : Peek-a-boo isn't a baby's favorite game just by chance: after a first birthday, a baby begins to understand that even when something isn't in his sight, it still exists. He expects that a person or an object will reappear eventually - and when the anticipated finally happens, he's delighted. This charming book, with flaps to lift and see-through die cuts, will help little ones solidify object permanence. There's even a place for a photo so that the answer to "peek-a-boo, who?" can be a family member . . . or perhaps the reader!