These stages are:
1. The sensory-motor stage (0-2): Children use senses and motor skills to explore their world and develop their cognitive skills. A main milestone of this stage is knowing something still exists even if they cannot see it.
2. Preoperational stage (2-7): Thinking is still egocentric. Children start to use language and classify items by a single feature.
3. Concrete operational (7-11): This stage marks the beginning of logical thinking. They can classify objects according to a number of features.
4. Formal operational (12+): Children start to think about abstract concepts and can