Is the student to be considered an oppressor or oppressed if the teacher deducts marks from him for not seeing who was standing at the window, due to his preoccupation with reviewing the book?

A Muslim must ensure the truth of what he says when testifying, because the basis of testimony is that it should be based on observation and knowledge. The texts of the Quran and Sunnah (definition) indicate that testimony must be based on knowledge, so it is neither heard nor accepted except from one who knows, and it is not permissible for him to testify except to what he knows and has verified. If you testified to what you knew and were then punished for it, you are wronged, and you should consult the teacher to clarify the matter.