Define the Role(s) of your Teaching Assistants

This page was written by Kelsey Bitting (Dept. of Geology, University of Kansas) and Geoff Cook (Scripps Institution of Oceanography, University of California San Diego), drawing on discussions and contributions from the 2014 Getting the Most Out of your Introductory Courses workshop.

Graduate and undergraduate students can serve in a wide array of both formal and informal teaching-related roles at colleges and universities of any type and size.. These roles are defined and assigned based on faculty and department needs, funding availability, and the pool of students available to fill the roles, including their strengths and skills. Graduate students who are hired to assist in the classroom are typically called teaching assistants (TAs) or graduate teaching assistants (GTAs) and are commonly awarded stipends and/or salaries for their work. Undergraduate students who assist in the classroom may be called undergraduate TAs (UTAs), learning assistants (LAs),or peer mentors, and are often compensated hourly or with course credit for their time.

Below, we describe a variety of TA roles from the least to the most experienced. Each description includes the level of knowledge and prior experience typically required to fill the position, standard time commitments for each role, and typical responsibilities and job tasks attributed to each.

Classroom Mentor

Classroom mentors are often undergraduate students who have taken the course and were successful in terms of content and skill mastery and who display a high degree of enthusiasm and interest.

Classroom mentors facilitate active learning by working with individuals or groups to model problem-solving strategies, ask questions to test and guide the exploration of concepts or encourage metacognition, reframe questions or concepts in new language to help learners connect to those ideas, and generally encourage student motivation and engagement. Classroom mentors are often easier for students to relate to and approach, and may get a clearer perspective of student stumbling blocks than the instructor, providing valuable insight for course design. Finally, classroom mentors who were recently students in the course can provide feedback and student perspective on new instructional tools before they are piloted in the classroom.

Learn more about Peer-led Team Learning, where classroom mentors play a key role.


Evaluating and giving timely feedback on assignments is an integral component of every college course, and GTAs or LAs with prior course experience are in a good position to help complete these duties. The time commitment of this role varies widely, from a few hours to more than 10 hours per week.

Tasks performed by a grader may go well beyond checking students work against a standard key or rubric, and can include identifying and recording common misconceptions and relaying them to the instructor, providing targeted feedback to improve student performance, and evaluating how well students achieved the learning goal of an activity or assessment.

Lecture Assistant

Within large lecture courses, lecture assistants may take attendance, help distribute or collect student materials, assist with lectures or demonstrations, organize and staff field trips, proctor and grade examinations, manage storage and transport of teaching materials, and assist in calculating overall course grades. Depending on the institution, lecture assistants may also hold office hours for students in the course, run review sessions, and/or serve as discussion group facilitators.

Laboratory Instructor

At research universities, especially in life and physical sciences, GTAs are the primary instructors for the majority of available discussion sections and undergraduate labs. At primarily undergraduate institutions, senior-level undergraduate geology majors may also serve in this role.

Typical responsibilities of this position include giving short talks or leading short discussions to reinforce concepts learned in the lecture portion of the course, guiding students in lab activities or investigations, grading labs or homework assignments, leading field trips, and administering and grading exams. Depending on the level of support or infrastructure provided by the instructor, head TA, or department, laboratory instructor TAs may be responsible for writing their own syllabi, setting and enforcing classroom and grading policies, and developing new instructional materials. Laboratory instructors are often perceived by undergraduate students as being more approachable than the professor of an associated large lecture course, and may therefore field a wide range of content- or skill-related questions about the paired course as well.

Discussion Group Facilitator

If a large lecture course includes optional or mandatory small group meetings for discussion or problem-solving practice, GTAs or LAs commonly serve as facilitators. Discussion group facilitators commonly fulfill a wide range of responsibilities similar to those of a laboratory instructor, though exams are not common in discussion sections.

Head TA

Where a large lecture course is supported by multiple sections of a paired laboratory taught by several different TAs, some departments designate an experienced senior GTA to serve as head TA. The head TA typically garners additional salary and/or recognition above the average GTA compensation within the department.

Head TAs may support the TAs teaching lab sections by running weekly meetings that include having the TAs work through the coming week's activity, ensuring that all TAs understand the content and have mastered the skills necessary to guide students through completion of the coming lab, and collaborating on problem solving in classroom management or grading issues. Head TAs may also develop a common syllabus and policies for all lab sections. They can also assist in developing and enforcing timelines for grading and returning student work. Finally, head TAs can work with the instructor to clarify learning goals, improve alignment between the lab and lecture, craft rubrics and keys for more consistent grading, and serve as an intermediary between the instructor and other TAs.


At many larger institutions, senior GTA's (typically PhD students) may be called upon to serve as the primary instructor for introductory (and sometimes upper division) courses. This type of position may require a significant time commitment on the part of the GTA, but it can be an enormously valuable experience, particularly if the GTA has further college-level teaching ambitions.