Five main theories

Essentialism: The 'essential core' needed for a sound education. Plato started it, and Britain carried on for its elite, with different systems for trades and laborers.

Encyclopedism: Much broader base and available to all. Comenius started it with the first textbooks, and most European states still follow the same principles.

The sensory-based early-start model: Aristotle first proposed that knowledge comes first through the senses. Itard, Seguin, Rousseau, Pestallozi, Froebel and Montessori have developed variations.

The pragmatic child-centered movement: The original American breakaway, with Dewey the pioneer. Now two main strands: one around the individual child, and other to `reconstruct society'.

The common-sense aproach: as new insights emerge from research and practice, and as technology makes it easy to retrieve information, forget dogma, select the best from all, and keep an open mind.

* Plus the Confucian academic examination model, still popular in Chinese societies, Hirsch's Cultural Literacy, and Piaget's theories of phased intellectual development.