The grading part of the teaching assistant job is the most time consuming and the least rewarding of all. If you are a new teaching assistant, you will find yourself spending incredible amounts of time grading. While you grade, you will discover that your grading scheme is imperfect, you will feel that you are removing too many points here, not enough there, and you will going back and forth several times through the endless stack of homeworks.
This document is in the works. For some other
good advice on grading, see Michael's cs154 document
This note gives a number of advices on how to grade efficiently. It mostly comes from experience TAing undergrad theory classes in computer science, and might not be applicable to all.
Choosing a grading scale (read 10 hws and put comments, select only two or three possible "base" grades (perfect, ok, bad))
Standard comments (put a code for the standard problems, so that you only have to write the code if the problem is identified)
Inconcistencies are not harmful --- show computations of how likely it is that a small inconsistency will affect the grade.
If the student showed a good understanding of the problem and his answer is right apart from some small mistakes, don't remove points just because your grading scheme tells you to do so.
If a student writes mostly wrong things or useless handwaving sentences, don't give free points by weight, even if there are a few things right in the answer. Handwaving should be discouraged at all cost.
When an answer is completely off, it is tempting to write ``See solutions''. You should not do that: it takes too much time just to write this. A red line crossing through the page will be much faster to draw, and will be as good an incentive to go and check the solutions.
As with every boring job that is not done under close supervision, the most significant waste of time comes from day dreaming. Avoid day dreaming either by working short shifts. Alternatively, you can set an alarm to ring every ten minutes, and verify that you keep a steady grading pace.
The scrupulous TA will often want to have a perfect grading scheme, such that if he were given the same homework to grade twice, he would give exactly the same grade. Achieving this goal is both very time consuming, of statistically small value, and has undesireable side effect (we expand on this later in the text). Instead, for a given question, you can define three focal grades,
Decide at the beginning of the quarter (or ask the instructor) if the students should learn to express themselves clearly. If so, reserve a significant fraction of the points for each question to "clarity". Remove these points anytime the solution is confused.
Whether grading is performed fast or slowly, you are bound to make some mistakes of two types: (1) giving credit for a wrong solution, and (2) not giving credit to a good solution. The first ones, you will never hear any complaints about, so it is important to try to avoid them as much as possible. The second one will happen, and you should be ready to recognize your mistake. However, if, after a student comes to you and explains to you his solution, you still find it wrong, don't give any extra credit.
Some students come to complaint about the grading scheme, and to ask for more partial credit. You should not give extra points unless you are sure you oversaw something when you graded the first time, as giving free extra points for complaining would encourage students to do so more and distort the (relative) fairness of your grading.
If a student is too insistent, tell him either (1) to go and see the professor, or (2) to fill in a written complaint that will be examined by the professor.