Although homework is generally thought to be negative by the large part of the student population, it actually does have benefits. The main thing that makes teachers go wrong with it is by over doing it. The reason for homework is to refresh and sustain the things that you learned in class. Reasonable for math: worksheet with 15-25 problems depending on level of difficulty. What teachers actually assign: 50 math problems that take an average of 4 minutes to calculate. If we had reasonable assignments, which we sometimes do, homework would not have the extreme negative connotations that it does.
In a perfect world:
Teacher: Alright kids, for your ninth grade English homework today read a chapter, and write a four sentence summary.
Kids: Ok! That should take about twenty minutes! Yay!
Teacher: Alright kids, for your ninth grade English homework today read five chapters, and give me a page on the representation of disestablishmentarianism in the novel.