Full-time workers usually receive health coverage and other benefits. Teacher assistants who work part time ordinarily do not receive benefits.
In 2004, about 3 out of 10 teacher assistants belonged to unions—mainly the American Federation of Teachers and the National Education Association—which bargain with school systems over wages, hours, and the terms and conditions of employment
Source: Bureau of Labor Statistics, U.S. Department of Labor, Occupational Outlook Handbook, 2006-07 Edition