Is it sufficient to provide the national ID number to the subject teacher, along with an explanation for not wishing to reveal the face, given that the student is a Niqabi, or what is the correct action in this situation, bearing in mind that the Maliki madhhab is followed?

A woman's hijab and modesty in front of men are religiously required and commendable. There is no objection to providing a copy of your national ID card or any document bearing your modest photo when necessary, with viewing limited to what is required for identification purposes. The male employee is not permitted to look at it for any other reason. If it is possible to suffice with the ID card number, that is preferable; otherwise, there is no harm in giving it to him while adhering to the aforementioned conditions.