Cognitive Development refers to how a person perceives, thinks about, and gains understanding of their world through interaction and influence of genetic and learned factors.
This is the scientific study of mind as an information processor - it looks at how we process information we receive and how this processing leads us to respond in certain ways.
This term refers to brain's ability to reorganize itself by forming new neural connections throughout life. It allows neurons in the brain to compensate for injury or disease or adjust their activities in response to new situations or changes in the environment.
In context of cognitive development, assimilation is the process by which we take in new information and incorporate it into our existing mental framework.