The heart of Psychology

To draw information from all areas given by the teacher and create a working human theory. To be used to redefine the way we teach students based on information on Maslow. The benefits of intelligence under level one stage which 0-3 years of stage under Piaget's method. Then why methods piggy back on Erikson's theories are used just like Freud's ego lifespans. What is the foundation to all the theories and what is common between them all.