"I don't tell my students this," I tell my student--but she's a special student, the intern serving as teaching assistant in my first-year writing class, and if her goal is to understand the tricks of the trade, I'm going to have to reveal a few of them.
Today I showed her my special grading rubric, the one with the pull-down menus that allow me to click on certain comments I need over and over, like "great thesis!" or "more plot summary than analysis" or "choppy--too many short, simple sentences." After I've clicked on the relevant canned comments for a particular paper and added more individualized comments as needed, I save the rubric as a pdf and send it to the student, who doesn't need to know about my pull-down menus.
I've also admitted that one reason I require students to write interesting titles on their essays is so that I'll always have something positive to say from the start ("Great title!"), and I've revealed the existence of the Necessities Drawer in my desk. "Every teacher has a place to put the stuff she needs to get through the semester," I told her; "only the contents differ." (Cough drops, eye drops, antihistamines, plastic spoons, granola bars, chapstick....)
If teaching is a performance, then my teaching assistant needs to learn how it works from backstage, all the props and illusions and preparations that make the show look effortless. Showing her how the magic trick works may minimize the glamor of the profession, but how else will she learn to make her own magic?
Besides, I'm not in it for the glamor. I'm in it for the granola bars.