Studied the natural process that children go through to develop their ability to reason. piaget cooley flavel mead

I believe the answer is Piaget.
Piaget divided the children's development into Four stages of Development.
He based the stages on the assumption that our brain develop a certain capability/capacity as we grow older, and our cognitive ability also increased alongside it.

The  frame of government of pennsylvaniawas a constitution for the  province of pennsylvania a  proprittarycoony granted to  william penne by  charles ii of england. the frame of government has lasting historical importance as an important step in the  development of american and world democracy.