It is better and safer for these women to look for a woman who can teach them Qur’aan memorization, whether in the home or in the mosque, because that is further removed from fitnah (temptation) and its causes. If that is not possible, but these woman can memorize Qur’aan using tapes or a computer and then check on one another, that is good, and it is better than sitting with a man in order to memorize.
If there is a need for this man to teach them, either because there is no female teacher or because he is good, and can teach them the rules of tajweed (correct recitation), then there is nothing wrong with that so long as attention is paid to the following guidelines:
1- He should teach them from behind a screen.
2- None of them should speak in a soft voice.
3- They should speak with the teacher only as much as is necessary.
4- The teacher should give up this job if he feels that his heart is inclined towards one of them or he enjoys the sound of the voice of one of them.
5- The teacher should be elderly, married and known for righteousness and piety.
It should be noted that the voice of a woman is not ‘awrah according to the more correct of the two scholarly opinions, so long as there is no softness of speech.
It says in Kashshaaf al-Qinaa’ (5/15), which is a Hanafi book: Her voice (i.e., the voice of a non-mahram woman) is not ‘awrah. It says in al-Furoo’ and elsewhere: according to the more correct opinion, but it is haraam to enjoy listening to it even if she is reciting Qur’aan, for fear of fitnah. End quote.
It says in Mughni al-Muhtaaj (4/210), which is a Shaafa’i book: The woman’s voice is not ‘awrah, and it is permissible to listen to it so long as there is no fear of fitnah. End quote.
It says in Fataawa al-Lajnah al-Daa’imah (12/156):
Firstly: mixing between men and women in schools and elsewhere is a great evil which causes a great deal of damage to religious and worldly interests. So it is not permissible for a woman to study or work in a place where men and women mix, and it is not permissible for her guardian to allow her to do that.
It is not permissible for a man to teach a woman who is not wearing hijab, and it is not permissible for him to teach her when he is alone with her even if she is wearing proper shar’i hijab. In the presence of a non-mahram man, the entire woman is ‘awrah, and covering the head but showing the face is not full hijab.
There is nothing wrong with a man teaching a woman from behind a screen in a school that is just for women, with no mixing between male and female students, or between the male teacher and the female teachers.
If you need to ask him questions, then it can be done via closed circuit TV, which is well known and widely available, or over the phone, but the students must beware of speaking softly or making their speech attractive. End quote.
And Allaah knows best.