A schema is a representation or a map of a pattern of events. It is essentially the building block of knowledge. Infants’ initial knowledge of the world is through action schemas or sensory-motor schemas. This means the child can only know the world through immediate sensation or direct action, such as bringing the thumb into the mouth or seeing bicycle wheels go round and round. Around nine months of age, these action schemas begin to exist in the mind alone. In other words, the child can think about the event when it is not actually occurring. The mental life of the child has begun. A mental representation of an event is called a conceptual schema. One sign of this is called object permanence, which occurs around nine months of age when an infant will look for an object after it is hidden from view, such as searching for a rattle after it is hidden behind a pillow.