Check my writing

Are there any mistakes? If so, correct me.

Doing homework might be the hardest task for some students. It depends on their teacher and the amount of homework they get. Most students think that homework is absolutely waste of time. This might not be true for some reasons.
From my point of view, homework is not always waste your time; Homework is a set of exercises teacher assign (or order?) us to do, to recap the lesson we have learned and again it depends on the teacher. Some teachers give us a homework that will be used on their exam so we have got to do it; otherwise, we will be failed on the exam.