Can anyone tell me what the most important theories of Jean Piaget are??There is a lot of information on him and I want to narrow it down to the...

In my mind, the most valuable contribution Piaget made to developmental psychology was the idea that learning and understanding within children's minds are not always direct and predictable.  Student learning is directly impacted through their own sense of psychology and mental awareness.  Due to this, there is a developmental growth that allows the mind to "be ready" to receive this learning.  Piaget saw learning as a result of mental construction, where the mind advances through stages of this development, allowing it to be more receptive to learning.  With Piaget's contribution, educators understand that there have be different need for different students and that the awareness of psychological development is critical in student comprehension and learning.  This is powerful in terms of evaluating students and understanding how to teach them.  The introduction of "stages" became a critical element in how teachers scaffold lessons and how schools can meet students' needs in a more beneficial manner.