Should the head of a school oblige the female students to wear niqab (whilst they are within the school's premises)? Or should it be kept optional?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Scholars held different opinions regarding the ruling on covering the face with a Niqaab (face veil) or something else in the presence of non-Mahram men (i.e., marriageable). The majority of scholars held that it is recommended, while some scholars held that it is obligatory. The second is the opinion Islamweb holds as preponderant. It is impermissible, though, to oblige the female students to wear the Niqaab when scholars held different opinions regarding its ruling, especially since there might be among these females a seeker of knowledge (i.e., Islamically knowledgeable) who considers the view that the Niqaab is not obligatory to be preponderant, or another who follows a scholar, whom she trusts, who chooses this opinion.

However, this principal should be keen on enhancing the faith of her students through holding religious lectures and inviting callers to Allah who are endowed with knowledge, forbearance, and wisdom to educate them on their religion and provide them with insightful guidance. Verily, this yields abundant rewards, as whoever leads others to a good deed earns equal rewards to the one performing it.

Allah knows best.