sentences:  Eager to share his knowledge in the field with students, he subsequently went into teaching; in the 1950s to 1960s he held teaching positions at American University, the University of Washington, and the University of Illinois, as well as Wright-Patterson Air Force Base.In 1958, Hayes was hired as a vice president of Electrada Corporation, where, together with John A. Postley, he created Advanced Information Systems as a subsidiary of Electrada.At the 1962 Seattle World's Fair ("Century 21 Exposition") Hayes led the training program in library automation for the professional staff of the American Library Association (ALA) exhibit, "Library 21", which aimed to introduce online retrieval to the general public.