My first assignment as a teaching assistant was to lead discussion sections in an introductory philosophy course (and the department chair’s son was in my section!). I received no training, supervision, or direction; I was expected to know what to do by reflecting on my experience as a student, or to infer it from the professor’s lectures. I wondered, to my distress, whether perhaps the professor was just uninterested in what I did.
I discussed my plight with the other first-year teaching assistants, and learned that their situations were the same. We met as a group of peers, pondering how we might best serve the students in our charge. All adrift, we knew we must find our own way. One happy outcome was our development of expository notes that we wanted all the introductory students to have in common; those notes evolved into a little text that had 14 printings and then two further editions. We shouldn’t have had to write that book ourselves, but writing a primer for beginners was not prestigious philosophical work.
That experience fueled a lifelong interest in the training and mentoring of teaching assistants. I don’t see them as labor-saving devices, independent professionals, or colleagues of equal standing. They are both craft apprentices providing a crucial service to undergraduate education and students to whom we have a solemn teaching responsibility -- not just in our graduate courses, but in their capacity as our assistants.
Decades later, arriving at Syracuse University as dean of the College of Arts and Sciences, I found congenial administrative colleagues who shared this view and helped develop a university-wide TA Training Program,  and who later created the Future Professoriate Program. 
These ventures have flourished institutionally. Yet I remain dissatisfied with what individual faculty are doing with their own assistants – as if this centrally provided training freed them of their responsibility as mentors.
There’s no single formula for mentoring effectively. What has worked well for me might be entirely unsuitable for a colleague with her own distinctive style of guiding assistants. Yet each of us might benefit from knowing what the other one does. Much has been written about mentoring, but too often it lacks the operational specificity that enables effective improvement. And much of it is about the parts of teaching that take place in front of students in a classroom or lab, while too little is about training for sophisticated evaluation of student work. These matters merit broader discussion. In that spirit, I hope that others would at least be interested to know about what I do, and would be willing to join the conversation by providing accounts of approaches they have adopted or abandoned.
The functions of TAs who assist me in a large class (i.e., any class with more than one TA) include (a partial list): conducting discussion sections, holding office hours for individual students, grading papers, helping proctor and grade exams, monitoring what goes on in lectures and providing critical feedback to me about all aspects of the course. I’ll comment here on just two of these TA roles: leading discussion sections and grading essays.
For each weekly set of discussion sessions, I meet with the TAs to go over what the goals should be for that week’s sections. I meet with them afterward to hear an assessment of what actually happened -- to learn what they discovered from their students about what was clear and what was problematic, gather complaints or suggestions, and discuss what adjustments or additions might be useful in the next lecture.
Before allowing a TA to grade a student’s paper, I want to be sure the TA is sufficiently trained. Evaluating the written work of another is a demanding intellectual undertaking, especially when both substantive content and expository quality are under scrutiny. Few graduate students have had significant experience of this kind within their disciplines.
Here’s what I typically do (with small variations from course to course):
(1) Each TA must write the first essay that will later be assigned to the undergraduates, and submit that to me. I mark it up rigorously and return it. (Sometimes I get a different writing sample from them.)
(2) When that first essay is collected from the class, I gather a random set of perhaps 4-6 papers. I photocopy one, mark it in detail, and give each TA a copy of the marked paper to study. I also give each TA a copy of the remaining unmarked papers from the selected set. The TAs must mark these papers, guided by the model I provided.
(3) We meet and array the results. That is, for each paper, we put on the board the grade given by each TA. We then go through each paper, page by page, with a critique of the grading. So, for example, if TA Jones marks "non sequitur" in the margin of paragraph 4 on page 3 of paper B, but TA Lin has not written that, we discuss whether there is or is not a non sequitur here, and whether that comment belongs on the page. If it does, why did TA Lin miss it? If it does not, why did TA Jones write it? We do this for all the selected papers until we agree about what should be written on each paper and what the grade should be. This meeting can take 4-5 hours. The goal is to create such a solid commonality of understanding and approach that the grade a student gets will not depend on which TA grades the paper, and further that the rigor of the feedback will maximally benefit the student.
(4) Each TA then selects a paper from his or her section, grades it, and submits that to me for approval. If I am convinced that the TA now meets the required standard of quality, the TA goes on to complete the grading of the rest of the papers.
This large front-end investment results in far better papers coming from the undergraduate students after the first one is returned. It produces a fair, albeit tough, standard of grading. Because it is a transparent process, with students in the class aware of what we are doing, they accept the grading as fair. Almost without exception, the TAs who have been trained in this way affirm that it greatly benefits their own writing and contributes to their success as teachers.
Again, I do not suggest this for everyone, but we should each be interested in what is done successfully by any of us. Discussing these matters should be recognized as important to any department with a graduate program. Academic leaders should catalyze this recognition, legitimate such discussion, and even reward departments that demonstrate improved practices.
Samuel Gorovitz is professor of philosophy at Syracuse University.