I sometimes find potential errors in slides/notes that professors provide us as studying material. These are often some distraction or algebraic errors, other times lack of formalism that might generate misunderstanding.

As a PhD student, should I let them know, so that they can correct themselves in the case that my intuition was correct?

Sometimes I am not 100% sure of my claim and I would find it interesting just to know how right/wrong I am. Others I would like to appear kind, if they were interested in polishing their notes. However, I am afraid that professors might take it as a challenge, and therefore I would like to know to which extent this is appropriate.

  • Related: academia.stackexchange.com/questions/177491/… Commented Apr 27, 2022 at 11:50
  • When are these slides given out relative to the lectures (or whatever) in which they are used?
    – Buffy
    Commented Apr 27, 2022 at 12:28
  • The question seems ambiguous as a matter of English usage. "Let them know" is a common idiom for "tell/inform them" and is probably what is meant here. But "let them notice" is not an idiom of this sort and, to my ear, suggests the opposite: not telling them and instead letting them notice (or not) on their own. As in: "I didn't speak up and tell the professor when I first saw them write the term with the wrong sign; rather, I stayed quiet and let them notice it themselves when they arrived at a final result that they knew didn't make sense."
    – nanoman
    Commented May 2, 2022 at 1:45

4 Answers 4


I think it's a great idea to let professors know if they have made a mistake in their slides and presentations. As a PhD student it's excellent to develop a confident and comfortable relationship with your supervisor and acting as a kind of second set of eyes and peer reviewer will likely be appreciated. Professors are often very busy and having to create learning resources very quickly for class, talks, etc... If you are able to assist them and pick out small errors that make them look better and more professional I think they'll really appreciate it in the long run. The only thing I would avoid is acting pleased or condescending when you do find errors. Make sure that you are pointing out mistakes from a place of support and teamwork rather than as a "gotcha" moment where you're proving that you're smarter than they are. If you can act as a helpful colleague in this situation I think it will be beneficial to your supervisor/student relationship overall.


If professors take it as a challenge if you notify them of an error in their teaching material depends on their personality. However, generally it is in the interest of the professors to have correct material. So I would usually advise to let them know of possible mistakes. It happens occasionally to me, and I am always grateful. Keep in mind to be polite, not accusatory. Thus, you also have a good chance to get a helpful reply in case you misunderstood something.


To reiterate other answers, with perhaps some slightly different perspective/emphasis:

Yes, conscientious lecturers do not want to make mistakes, not even typos, and would appreciate polite in-the-moment corrections, to not have to worry about later corrections.

"Of course", an interruption of the form "You're an idiot: look at what you wrote" is not helpful to anyone. Sure, people commit ridiculous typos all the time, no matter how careful the proofreading. So, instead of declaring the speaker an idiot, say something like "pardon me, an obvious typo, I think, or maybe I'm misunderstanding something".

If there is a disagreement more substantial than about typos or notation, it probably won't be resolved in-the-moment, so don't push it. Hopefully the speaker has enough sense to accommodate substantial question about some part of the presentation...

  • It is a myth that you’ll end with typos no matter how carefully you proofread. Unless you have dislexia, ADHD or something like that.
    – user354948
    Commented May 18, 2022 at 17:54
  • 4
    @user354948, well, I guess I'm "living the myth". :) I don't think I'm dyslexic, nor ADHD'd, but simply write a lot. The marginal benefit to proofreading decreases, obviously, and the time spent looking for the last 3 typos could be better spent elsewhere, for me. Commented May 18, 2022 at 18:16
  • Well, yes, of course, the law of diminishing returns works.
    – user354948
    Commented May 18, 2022 at 18:28

Tell them one or two of the most significant errors. Then if they say "thank you, please tell me any more" in a pleasant way, you can tell them some more, still in a nice and helpful way. If they just say "OK" in a gruff way, you can leave it there, as they probably don't want to be told about any more.

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