What are Piaget's four stages of reason?

Jean Piaget, a Swiss psychologist, proposed four stages of cognitive development, which he believed all children go through in a specific order. These stages are:

1. Sensorimotor Stage: This stage occurs from birth to age 2. Children at this stage learn about the world through their senses and motor activities. They develop object permanence, understanding that objects continue to exist even when they can't be seen.

2. Preoperational Stage: This stage occurs from ages 2 to 7. Children at this stage are egocentric and struggle with understanding the perspectives of others. They also begin to develop language and use symbols to represent objects.

3. Concrete Operational Stage: This stage occurs from ages 7 to 11. Children at this stage begin to think logically about concrete events and understand the concept of conservation (that quantity doesn't change when its shape changes).

4. Formal Operational Stage: This stage occurs from age 12 and up. Children at this stage develop abstract thinking and can easily solve problems hypothetically. They can also think about moral, ethical, social, and political issues that require theoretical and abstract reasoning.