Final answer:
Piaget's theory of cognitive development suggests that children construct their knowledge by actively interacting with their environment.
Step-by-step explanation:
The assumption about children's cognitive development that was derived from Jean Piaget is that children construct their knowledge.
According to Piaget's theory of cognitive development, children actively participate in the construction of their understanding of the world. They do not passively absorb information like blank slates, and knowledge is not funneled into them. Instead, children actively interact with their environment, create mental models called schemata, and adjust these schemata through assimilation and accommodation processes.