Jean Piaget proposed that children were not just small grown-ups, but that they learned in a qualitatively different way from adults. He described children as active participants in their own learning, constructing their own understanding and furthering their own knowledge.
Piagetian theory has been such a strong influence on early years practice in the UK that it is easy to overlook how radical his ideas were at the time. Piaget's image of the child as little scientist was in stark contrast to other perspectives in Europe and the USA over the same period. The prevailing educational belief about children was that they were essentially empty vessels who needed to be filled up with adult-given knowledge.
Piaget proposed that between 5 and 7 years of age children make the shift into a whole new level of thinking, that of operations - mental activities such as categorising, use of number and early scientific concepts. This new level of understanding took children into the concrete operational stage which Piaget believed lasted up to about 12 years of age. By the brink of adolescence, children have gained such a broad and thorough understanding of ideas in action, concrete operations, that they were able to deal with increasingly complex ideas in their head and move to the stage of formal operations.
If we agree with this, why do we formalise our children's education so early?