Piaget

Nature, intellectual developmtn happens in stages, only move on when each stage is completed. 'Building block.' 

Sensori-motor 0-2: Infant knows world via immdeiate senses and motor it performs. Cannot distinguish between self and environment. Lack internal schema(how and why). Lack object permenance, cant see it, its not there. A hidden object is not looked for until 8 months, where it is looked to see if in the same place it was last found. Early years workers should enable them to explore senses and use visual aids at this stage.

Pre-Operational 2-7: Add/create schemas, domainated by sensory motor. Cant carry out logical operations. They are egocentric, others see/feel same. e.g three mountains. Lack conservation, unable to realise things are the same (water in jars). Object permenance has increased, know mum has gone. Resolve egocentric conflicts, teach right and wrong. Objects have feelings, learn through play.

Concrete operational 7-11: Mental operations are carried out, conserve and class inclusive taks, egocentrism is overome. Must be concrete actions, not in head. Conservation occurs, use experiments to support this. E.G. Counters ect.

Formal operational 11+: Ideas in head, think hypothetically, plan, systamatic approach. Work in head, plan lessons to enhance logical operations.