Piaget

Jean Piaget mapped out the stages and ages through which he based his theory.  These stages give a theoretical framework for his empirical finding to our understanding of the growth of logical thinking in young people. Of particular interest to teachers of science are the formal operational schemata of variables, classification, proportionality, combinations, correlation, probability, compound variables, formal models and equilibrium.

Now we need to make sure that you really understand the meaning of early concrete (2A) to late abstract reasoning (3B) in a school scientific context.