Does saying ''I don't know" often decrease my authority as teaching assistant? I worked as a TA for several courses. Some courses fall into the domain in which my research also happens. But some other courses are not at all familiar to me.

My Institute conducts tutorial classes with an objective of addressing students doubts in that course. Only TAs attend to this class. It is of the duration atleast couple of hours. 

Students start asking the questions, that are difficult for whole class (because of the reason that they communicate among themselves the solutions of questions). 

For the courses that are not familiar to me, it becomes difficult to answer the questions asked by them. Students expect the answer instantly on the board and it is a norm also. 

In-order to face the situation honestly, I need to tell I don't know for the questions they ask. I feel it is okay to tell my ignorance for some questions since I am not a professor or expert in that course. 

If I start saying it honestly for all questions that are difficult for me, then I feel that there will be an increased disrespect on me among students circle.

Is it true that the respect for the TA decreases the more often frequency they reply "I don't know"?

Note:  Attending the professor classes as TA or spending more time on the course is not solving my issue since students are asking questions that are very difficult as they collect questions from several online materials that demands more in-depth knowledge. And professor asks to conduct the classes properly. Some TAs intentionally avoid tutorials to avoid this issue. So please refrain from the answers that provide solutions to the question of: how to handle this
Is it a true phenomenon that the respect on TA decreases with an increased frequency of I don't know replies?


Certainly not in the sense of "you have 5 'I don't know' per semester, and then you lose the student's respect. It really depends on what questions you do answer, how you answer them, and what kind of questions you are unable to answer.



If you normally provide good, instructive answers to questions with the occasional "I don't know" mixed in, no reasonable person will lose respect for you - especially if you commit to finding the answer to the questions you are unable to answer, and then follow through.

That said, it depends on what the questions you aren't able to answer are. If those are questions that could in a very similar scope also be on the exam, not knowing the answer (and not being able to derive it in reasonable time) will indeed not reflect well on you. If that is the case, preparing better for teaching the course (or teaching courses closer to your field of research) is really the only way forward. Otherwise, the students have all rights to be annoyed - what could they learn from a teacher who doesn't sufficiently master the course themselves?


  I worked as a TA for several courses. Some courses fall into the domain in which my research also happens. But some other courses are not at all familiar to me.


Maybe I'm stating the obvious, but that's really not the student's problem. The students should have an expectation that their teacher is qualified to teach the course, whether it's in their area of research or not. You should not expect leniency from the students because you are teaching a course outside of your field of research.