U.S. Air Cadets Study At Yale University -- The historic classrooms of 240-year old Yale University are now being used for technical training of 2,700 cadets of the U.S. Army Air Forces. Here students who have already received basic training are listening to a lecture on an aircraft machine gun. Virtually all U.S. colleges and universities are now engaged in training members of the American armed forces. March 22, 1943. (Photo by Interphoto News Pictures, Inc.).