Some TAs allow students to rewrite papers for a higher grade. TAs' policies on this issue vary. Some TAs will not accept rewrites at all; some will accept rewrites of papers receiving a grade of B- or less (or a B, or C, or whatever); some will drop the first grade and replace it with the rewrite grade; some will average the two; and some will list specific changes that the student needs to make in order to achieve a raised grade (e.g., if the student demonstrates a marked improvement on a specific issue, say by reorganizing the paper's logic or adding successful transitions, the TA may bump the grade up by 1/3 of a letter).

In general, your rewrite policy is up to you, but you may want to clear it with the professor beforehand. One disadvantage of allowing students to rewrite papers is that it can be quite time-consuming for all involved, but there are ways of reducing the time it takes to grade a rewrite. If the student turns in the
original paper along with the revision, it is easy to tell whether s/he has improved. Some advantages are that it allows students a second chance or a series of second chances to improve their writing, which can lead to immense improvement in their writing skills over the quarter (which in turn is satisfying for the TA), and. that it can prevent grade disputes. If given the opportunity, many students unhappy with a grade they've received will rewrite a paper rather than haggle with you about their grade.