Reflective Thinking and School Learning

The ancient Greeks urged the student: 'Know thyself At the beginning of this century, John Dewey talked of 'reflective self-awareness'; today, we invoke metacognition. All refer to a concept that has been known by good teachers for centuries, and that has very powerful implications for education. What is it?
One of the interesting characteristics of people is that they not only behave, but can watch themselves behaving, and believe that they can exert a certain amount of control over how they behave.
In other words, people are active agents: they reflect upon the knowledge that they gain about themselves, and use it so that they perform all the better. To the extent that they do, so they are being metacognitive.