Final answer:
During the sensorimotor stage, children learn about the world through their senses and motor behavior. They explore objects by putting them in their mouths or shaking and banging them. By 5-8 months old, they develop object permanence, understanding that objects still exist even if they cannot be seen.
Step-by-step explanation:
The first stage is the sensorimotor stage, which lasts from birth to about 2 years old. During this stage, children learn about the world through their senses and motor behavior. Young children put objects in their mouths to see if the items are edible, and once they can grasp objects, they may shake or bang them to see if they make sounds.
Between 5 and 8 months old, the child develops object permanence, which is the understanding that even if something is out of sight, it still exists. According to Piaget, young infants do not remember an object after it has been removed from sight. Piaget studied infants' reactions when a toy was first shown to an infant and then hidden under a blanket. Infants who had already developed object permanence would reach for the hidden toy, indicating that they knew it still existed, whereas infants who had not developed object permanence would appear confused.