PART-TIME teachers now account for more than half of all university and college staff in the United States. Their presence helps institutions cut costs but has angered students and unions.
There are more than 565,000 part-timers, including research and teaching assistants, among the nation's 1.1 million faculty members, according to the National Education Association, the largest teachers' union.
Part-time staff teach about a quarter of all college courses offered. "It is hard to think of any other industry that uses so many part-time professionals as a regular part of their staff," the association reported.
College and university administrators say employing part-time staff cuts costs and enhances flexibility. They make about half as much as a full-time professor at a public two-year college and less than a third as much as a full-time university professor.
Part-time employees also have no job security and receive no medical benefits, which in the United States are usually paid for by employers.
These inequities have angered part-timers. About 10 per cent of them have organised to seek better job conditions and more are trying to win union representation.
Ernst Benjamin, on the committee on part-time appointments for the American Association of University Professors, said: "Because they're so cheap, institutions really come to depend on them."
Full-time staff also resent part-timers, who they say limit their control of the curriculum. A meeting of full-time staff at the 14 state universities in Pennsylvania in January even agreed to give up higher salaries in exchange for a limit on part-timers.
Students, faced with escalating tuition fees, object to having many of their courses taught by low-paid, part-time faculty who are often unavailable for consultation outside the classroom.