Microcomputers were accepted by schools in the 1980s. Instructional television was used in the early-to-mid 20th century for both educational and wartime purposes. The Ford Foundation invested $170 million in educational television in the 1950s and 1960s. Educational psychologist Richard Clark concluded that media are vehicles that deliver instruction but do not influence student achievement. Behaviorism was the dominant pedagogical theory used in schools in the first part of the 20th century. Educational technology can be defined as the study and ethical practice of facilitating learning through the use and management of appropriate technological processes and resources.