What is the ruling of Islamic law regarding an involuntary erection that afflicts a teacher upon seeing female students who are immodestly dressed?

A man teaching girls in the manner described is not permissible Islamically, as it violates the Sharia (definition) regulations. A woman must wear the Islamic dress that covers her entire body, based on the Almighty's saying: {O Prophet, tell your wives and your daughters and the women of the believers to bring down over themselves [part] of their outer garments} [Al-Ahzab:59], and His saying: {And do not expose their adornment except that which [necessarily] appears thereof; and let them throw their headcovers over their chests} [An-Nur:31]. She must not wear perfume or adorn herself, and everyone must lower their gazes. The conversation should be limited only to the topic of the lesson, with safety from temptation. If any of these conditions are violated, teaching becomes forbidden. If the conditions are met, it is permissible, provided there is safety from temptation.