Can a daa‘iyah sit alone with a woman (khulwah) to teach her?

Praise be to Allah.

It is not permissible for the daa‘iyah to be alone with a woman who he is calling to Islam or teaching, because that is haraam, and the means to obedience and worship cannot be something haraam. End quote. 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him)