Piaget's theory
...he first two years of life, and is the ability to know things exist when they go out of sight. The ability for symbolic function is also acquired during this stage. During the pre-operational stage children start to talk but aren’t able to use reasoning or logic, they are egocentric as well. They have not learned to look at things from a point of view other than their own. This stage usually occurs between the ages of two and seven. After they are through with the pre-operational stage, they begin the concrete operational stage. They begin to be able to use concepts of time, space, and numbers. They realize that the shape of an object doesn’t necessarily change the volume. Their view on some fantasy objects such as the “Tooth Fairy”, or the “Easter Bunny” change to a more realistic view. They realize the impossibility of these things for the first time. They can reverse their thoughts, which gives them the ability to think of each relationship as one thing instead of two separate ones this stage lasts from around the age of seven until eleven. The fourth, and final stage is the formal operations stage children think more using abstract principles, and later are abl...