Peek-a-boo isn’t a baby’s favorite game by chance: after their first birthday, babies begin to understand that even when something isn’t in sight, it still exists. They anticipate that it will reappear—and when it does, they laugh in delight. This charming lift-the-flap book with see-through die cuts encourages little ones to play the game. With its simple rhyming text and pictures of familiar objects and animals, Peek-a-Boo What? helps solidify object permanence.