Montessori

Between birth and six years 60-70% of the adult intelligence is developed. It is during this time that the child has a unique aptitude for learning--an Absorbant Mind; A natural ability to absorb information willingly and with ease as a result of any experience the child has. It is during this same period that the child experiences 'sensitive periods', (periods of intense fascination for learning a particular skill, be it practical or academic).
It is of the utmost importance to cater for these sensitive periods at the opportune moment, because they are temporary and once past they are gone forever. Thus is the importance and great influence of the environment on the child's development.