IN 1893, Charles Eliot, president of Harvard, introduced to the National Education Association a novel concept: the credit hour. Roughly equivalent to one hour of lecture time a week for a 12- to 14-week semester, it became the basic unit of a college education, and the standard measure for transferring work between institutions. To be accredited, universities have had to base curriculums on credit hours and years of study. The seat-time system — one based on the hours spent in the classroom — is further reinforced by Title IV student aid: to receive need-based Pell grants or federal loans, students have had to carry a certain load of credits each semester.