Here is the somewhat awkward situation.

I am a TA for a class that I have never taken before. The professor (probably) knows this, but I don't think the students have caught on, since it is a lower-division class and as a graduate student I have significantly more mathematical maturity than most of them.

As a TA, I am responsible for preparing the lecture notes for the class. A different TA is responsible for grading assignments.

A few weeks ago, the professor made a (small) mistake in his lecture, and I transcribed the error onto the lecture notes without realizing it was a mistake.

Recently we had a midterm, and the other TA noticed that a lot of the students were making the same mistake. The other TA recognized it was wrong and is now docking points for the error, even though I told him there was a mistake in the lecture notes.

What should I do? I think the students will be mad when they hear about this, and if I tell the professor, he might get mad at me for preparing bad lecture notes.

Edit: It was the kind of error that would be confusing after the lecture, but hard to spot during the lecture. Basically he used a matrix where he should have used the matrix's transpose. And in the example problem he solved on the board, the matrix was a diagonal matrix, so it made no difference. But the matrix on the midterm wasn't.

2 Answers 2


Just tell the professor: "The transcription of the lecture included an error, and many students made the same error on the midterm." (It really doesn't matter whether the mistake was made first in the lecture or the notes.)

He will decide what to do about the midterm.

He will almost certainly be very happy to hear about his error from you, rather than from a large number of irate students (which is likely to happen if you don't tell him).

Nobody is infallible - not professors, not teaching assistants, not students. If he gets mad at you for preparing "bad lecture notes" for proliferating one mistake that he made, he is completely unreasonable.

As an aside: this evening, I gave my students a quiz, and during the quiz my TA - who was helping me proctor - pointed out an error. I thanked him and told the students to disregard that question. Then, after the quiz, I had the students get together in groups and work on "fixing" the question (the nature of the error made the fix non-trivial). It was an interesting and helpful educational exercise, for my students and for me. Errors can sometimes be an opportunity for good things.

Of course, I told my students that this is an important lesson on the dangers of taking code snippets off the Internet or from a book without carefully checking them :)

  • What if he doesn't remember he made the error, and assumes I just mistranscribed his lecture? It's the type of error that anyone could make and he might not remember making it.
    – user29315
    Feb 13, 2015 at 5:42
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    @user29315 it really shouldn't matter. Everyone makes mistakes, and it's totally unreasonable to expect you to never make any mistakes.
    – ff524
    Feb 13, 2015 at 5:43

I think this atleast partially depends on the maturity of the students. Are these first year students? Or perhaps students who struggle with math? Shouldn't they know enough to realize the error?

If you honestly transcribed the error as presented by the professor, I can't see where you're at fault. Your job isn't to fact check entire lectures. Since the other TA doesn't seem too keen on making adjustments, you may mention about asking the professor for input. If they don't seem keen on that, go to the professor anyways so they won't be blindsided with angry students. Mistakes in notes can be a headache.

Of course, to play devil's advocate, the case can also be made that the students didn't understand the material. They're regurgitating the same mistake made in the notes without asking questions.

It's a tough call, but at the very least (regardless of point deductions) the professor needs to know the situation.

  • I don't think the TA's action depends on the maturity of the students. The professor's actions, perhaps, but that's not what's asked here. (I agree with your second paragraph, though.)
    – ff524
    Feb 13, 2015 at 5:46
  • The thing is there's no proof that the professor made the error and not me. Because the official record of the class is my lecture notes. I think the professor has his own handwritten lecture notes but I don't know if he still has those or if he threw them away. So for this reason I feel skeptical of saying "hey professor, you made a mistake three weeks ago and now all the students are mad". What is the best way to approach the professor?
    – user29315
    Feb 13, 2015 at 5:48
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    I wouldn't outright accuse the professor of making a mistake, I don't think anybody here would tell you to do that. Rather, I suggest telling him that there is a discrepancy in the class notes that went unnoticed until after the midterm - and show him the exact issue in the notes.
    – Ramrod
    Feb 13, 2015 at 5:54
  • @Ramrod That sounds like a good idea, thanks.
    – user29315
    Feb 13, 2015 at 6:01
  • 1
    I wouldn't outright accuse the professor of making a mistake, I don't think anybody here would tell you to do that. — I would.
    – JeffE
    Feb 13, 2015 at 11:26

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