Piaget: Stages of Cognitive Development
During this period children learn how to classify things in two or more than two categories. They learn how to perform concrete operations. Concrete operations mean intelligent operations on concrete situations. So children are able to complete puzzles and make objects in the likeness of models.
Children know how to repeat or reverse their actions. For Piaget a genuinely intelligent act can be repeated, is reversible and in concrete operational stage children display this attribute of reversibility.
Children in this age group are able to use reasoning power in concrete situations , but they are not able to use this ability abstractly , means in their imagination .
Formal operation period(11-14)
During this period children develop full reasoning powers and they are able to think in abstract terms. They can solve algebraic problems and can solve problems in their imagination. In this stage reason is developed to its full strength , and whatever a child is not able to do in the earlier stages , he can do in this stage.