The duty of a TA or Grader is to assist the professor in teaching a particular course. The nature of the assistance required varies from course to course and from professor to professor, of course, but there are some responsibilities upon which there is general agreement.
In general, graders do not interact with students in a classroom setting. Rather, as the title suggests, they attend classes, grade all of the assignments, maintain grade records, and hold office hours for students who may need help. Occasionally, they may be asked to hold review sessions, paper-writing sessions, or something similar.
In addition to attending classes, grading assignments, maintaining grade records, and holding office hours, TAs run recitation sections for the course. Currently, we only have TAs for 80-100, 80-150 and 80-180 (although we may begin to have TAs for other courses as well). The format is as follows: there are lectures on Monday and Wednesday, given to the entire class (about 60 students) by the instructor, and there are 4 recitation sections (about 15 students each), run by the two TAs (2 sections each) on Fridays. In general, the TAs are expected to direct a discussion about the material in the course during these recitations, answer questions, go over homework, etc.; they are not expected to introduce the students to new material, although they may. More detail about the TA's interaction with students is given in section 5 below. In addition to the responsibilities mentioned above, TAs may also be asked to hold review sessions, paper-writing sessions, or something similar.
Many professors either create their own websites for their courses, or use the course management software, Blackboard. If either is the case, you should familiarize yourself with what the students will be seeing, and how the site will be maintained.
The expectations for both TAs and Graders will be unique to the course and the professor, and so TAs and Graders are encouraged to discuss specifics with the professor before the course begins. More detail about this discussion is given below.