His views of children’s cognitive and social development have been enormously
influential, particularly in educational theory. Piaget saw cognitive development
as being sequential, moving from one stage to the next once a child had acquired
the knowledge, understanding and experience to do so. Through different
experiences, a child would assimilate and adapt information, drawing on this
information when encountering new phenomena.
Piaget proposed that children's thinking (or cognitive development) does not
develop entirely smoothly. Instead, there are certain points at which it "takes off"
and moves into completely new areas and capabilities. Piaget saw these
transitions as taking place at about 18 months, 7 years and 11 or 12 years. This
has been taken to mean that before these ages children are not capable
(cognitively) of understanding things in certain ways.