Pedagogy encompasses both the practical skills of teaching as well as the underlying educational theory. It derives from the Greek term for the education of children. According to cognitive psychology, the human mind can be modeled as an information processing system. Jean Piaget's theory of cognitive development identified four major stages that students progress through. Teachers should understand students' cognitive levels to match instruction appropriately. Educational research is needed to develop effective curriculums based on scientific and psychological principles. Philosophers like Socrates have also contributed theories of instruction, with Socrates employing questioning to stimulate critical thinking. John Dewey advocated for participatory learning over traditional subject-based education.