Warning against male teacher being alone with a female student
Question

                What is the ruling on a male teacher being alone with a female student during a private lesson, whether in the home or elsewhere?.
Praise be to Allah.
    It is not permissible for a man to be alone with a woman or 
    teenage girl who is desirable, whether that is for a private lesson or 
    anything else, in the home or elsewhere, because the Prophet  (peace and 
    blessings of Allaah be upon him) said: “No man is alone with a woman but the 
    shaytaan is the third one present.” Narrated by al-Tirmidhi (2165); classed 
    as saheeh by al-Albaani in Saheeh al-Tirmidhi. 

    And he  (peace and blessings of Allaah be upon him) said: 
    “No man should be alone with a woman unless her mahram is present.” Narrated 
    by al-Bukhaari (3006) and Muslim (1341). 

    What is meant by “being alone” is their being in a place 
    where no one else can see them. 

    The stories which one hears about male teachers and female 
    students are very disgraceful, and mean that the girl’s guardian must be 
    even more careful and cautious. 

    The reason for that – and Allaah knows best – is that the 
    girl is usually young, at the stage of adolescence, when desire is strong, 
    and it is easy to deceive her, and she does not have enough common sense or 
    experience to be able to understand things properly and control her desires. 
    Moreover, lengthy interaction between the teacher and student, if it goes on 
    for a year or more, will gradually reduce the shyness and modesty between 
    them, which will make it easier to fall into that which Allaah has 
    forbidden. 

    The one who finds that he needs to bring a teacher for his 
    daughter must make sure that someone sits with them during the lesson, such 
    as her brother, or he should make sure that the lesson is given in an open area of the house, such as the sitting room, for example, and not in a closed room.