Female student speaking with her male teacher in the university
Question

                A young man teaches us in the university. Is it permissible for us to ask him questions and speak to him about the subjects we are studying?.
Praise be to Allah.
    In question no 1200 
    we explained that free mixing between men and women is haraam, and we 
    explained that harm that this causes to people’s spiritual and worldly 
    interests.

     As this is the case, then what you must do is not to remain 
    in a place where there is free mixing between men and women, except in cases 
    of necessity. If the university is for girls and the teachers are men, then 
    there is less danger. But those who follow their whims and desires will keep 
    trying to remove every barrier between the sexes. So we advise you to fear 
    Allaah and to remember that He is watching you in private and in public. 

    See also question no. 
    8827. 

    With regard to a woman speaking to a man for some necessary 
    purpose, there is no sin in it, subject to the condition that they should 
    not be alone together (khulwah or seclusion), even if that is in an office 
    or classroom, with no one else present. They should also remain formal and 
    dignified, and observe proper hijab, and take care to speak only about what 
    is necessary without saying anything more, or softening the voice. There 
    should also be no danger of fitnah.  If the woman feels any kind of desire 
    or speaks to men simply for fun, or if that applies to the man, then it is 
    haraam for them to speak together, because of the fitnah and sin involved. 
    And Allaah knows best. 

    See also question no. 
    1121, 10156.