The Preoperational Stage is divided into two substages: I. Symbolic Function Substage From two to four years of age children find themselves using symbols to represent physical models of the world around them. This is demonstrated through a child's drawing of their family in which people are not drawn to scale or accurate physical traits are given. The child knows they are not accurate but it does not seem to be an issue to them. II. Intuitive Thought Substage At between about the ages of four and seven, children tend to become very curious and ask many questions, beginning the use of primitive reasoning. There is an emergence in the interest of reasoning and wanting to know why things are the way they are. Piaget called it the "intuitive substage" because children realize they have a vast amount of knowledge, but they are unaware of how they acquired it. Centration, conservation, irreversibility, class inclusion, and transitive inference are all characteristics of preoperative thought.[62] 3. Concrete operational stage: from ages seven to eleven. Children can now converse and think logically (they understand reversibility) but are limited to what they can physically manipulate. They are no longer egocentric. During this stage, children become more aware of logic and conservation, topics previously foreign to them. Children also improve drastically with their classification skills. 4. Formal operational stage: from age eleven to sixteen and onwards (development of abstract reasoning). Children develop abstract thought and can easily conserve and think logically in their mind. Abstract thought is newly present during this stage of development. Children are now able to think abstractly and use metacognition. Along with this, the children in the formal operational stage display more skills oriented towards problem solving, often in multiple steps.
There are a total of four development stages described in Piaget's theory: the sensorimotor stage, the preoperational stage, the concrete operational stage, and the formal operational stage.
