ABSTRACT
By 1920 educational psychology had nearly 30 years of development as a subarea of psychology. Researchers in this applied discipline had established an empirical base focusing on learning, human abilities, and educational achievement. They were also involved in research and theory in developmental psychology, individual differences, and psychological measurement. In short, they had the theories, tools of measurement, research design, and statistical analyses to make major scientific contributions to curriculum and instructional methods, and indeed they had already made a sizable impact in America.
