I have been a teaching assistant for four years now. Last semester I attended a seminar on marking essays, and I realised that I have marked hundreds more essays than the person leading the session. In fact, essay-marking is my specialty. My old supervisor used to brag about my marking abilities to other professors, and I would sometimes get extra marking work from the other profs, because I was so well recommended.
It's not because my grammatical skills are exceptionally good. As evidenced by this blog. I don't know that I write the best essays out there, either. And I don't always know the field that I'm marking very well. (I was marking for 19th century Europe before I'd taken a course in it myself.) Why do profs like having me mark for them? It's because I'm an expert impersonator. And that's the necessary skill for the TA marker.
When you lead seminars, you get to develop your own style. You have to do that, in order to develop both rapport and authority. You're not going to go anywhere, doing your best impression of their prof. But when I'm marking essays, what matters most is consistency. And I impersonate to create this consistency.
I developed this ability in my early days of working for Dr. B. You see, even though I was marking all the assignments, he wanted to be the one meeting with the students. It was my first time working as a TA, and he wanted to ease me into it. In fact, for the first few assignments I didn't even suggest grades for him. He'd add his own comments, and then assign the grades himself. The students would get comments back on typed forms, which had a combination of his and my comments and corrections. It would be confusing if the comments seemed to come from two different people. And so I learned to adopt Dr. B's "voice."
Since then, even now that the students know I'm their TA and they're coming to me with their questions, I still have to keep up part of the impersonation act. Yes, we often are following a rubric, but different profs want different tones set. Am I firm, but fair? Do I make sure I begin with encouragement? Am I tough but constructive? All different voices. What happens if a student neglects some basic instruction, like Chicago style or page numbers? How do I respond to wikipedia? How freely am I allowed to fail a student, and for what purpose? I may have personal opinions on all of these issues, and I might mark these papers differently if these were my own students, but this isn't my class. I'm assigned to a professor, and he (I have always been assigned to males, so far) is the one who sets these standards.
I'm not complaining about this life. It's fascinating, and it's the best opportunity to try out a variety of marking styles. I'm developing my own voice and setting my own standards. Someday soon, I will be the instructor and I will make these calls. But, until then, I'm paid to impersonate.