Is it permissible to draw a face with its details in a university lecture if not drawing it will lead to a deduction of grades?

Many scholars have permitted drawing if it is limited to the face without the body, or if it is without a head, or with a head detached from the body. This is because a picture does not remain a picture after the removal of a part of it, just as an animal does not remain an animal after the removal of a vital part, such as its chest or abdomen.