Cognition means all events and processes of human mind ,for instance memory ,knowledge ,reasoning ,thinking ,perception and so on.
Development refers to the changes of these events and process according to the growth of the mind and other body parts.
According to the theorist Jean Piaget cognitive development the mind passes through certain stages according to age,thus the mind changes and the processes help to explain these changes.
In the theory of cognitive develpoment 'knowledge is structured' . The mind developes in stages and they are four of them.
(1)Sensorimotor stage 0-2 years old,
(2)Pre-operational stage 2-6 years old,
(3)Concrete operational stage 7-12 years old and,
(4)Formal operations 12-20 years old.
The schema basic unit of knowledge encoporates in the existing knowledge assimilation.
People acquire knwledge through accomodation ,or adaptation of knowledge and accommodation .
A sensorimotor type of schema the child have ,sucking ,crying ,grasping ,looking ,rooting and gradually engages in primary circular . At about 18 months develops object permanently.
Preoperational stage ,this is the phase where one is not yet operational when child starts to use symbols and sounds to represent thoughts. The way of thinking is egocentric and preoperational is captivated by surface features when children cannot classify things according to their attributes.
The concrete operational stage thinking becomes formal , thus operational thinking allow children to combine and arrange them in order. Children can transform objects and action 'desentriation' and they thinking capacity become reversible and properties of object remain the same even when altered.
Formal operational thinking become systematic ,the person can deal with symbols ,think abstruct ,hypothesise.
Implications in the teaching and learning process and materials for methods of instructions and aid learng must be plenty with a variety of concrete objects to be used by child to develop their language rapidly.