Application and criticism of jean piaget cognitive development?

The overarching criticism of all these types of psychologists is that there assertions are not supported by a scintilla of evidence.

The Servomotor Stage 0-2 years, which the infant learns many reflexes, The Preoperational Stage,ages 2-7 years old, where language is first used with meaning, the Concrete Operational Stage, ages...

concrete operational stage

Concrete operational stage: from ages 7 to 11 (children begin to think logically but are very concrete in their thinking) Children can now conserve and think logically but only with practical aids....

preoperational stage