Much to the frustration of nearly every student who reads this, I think that a good case can be made for the need to do homework. The most important reason is that homework reinforces the lessons taught in class. If utilized correctly, homework should serve as practice of the skills taught in class. Just as an athlete has to practice outside of games, and a musician has to practice outside of recitals, students need to practice their skills through completing homework outside of class. Homework enables the learning process to continue outside of the classroom setting. Students who simply attend class and do little outside of it are less likely to understand complex concepts and progress as well as students who work both within and outside of the classroom setting. Homework accomplishes this.
On another level, homework serves a sign of trust. It is important that students understand that a homework assignment should exist as a trusting bond between student and teacher. The teacher trusts that this assignment will be done at a particular time and the student must make good on that promise. I do believe that failure to complete homework reflects a deficiency of trust between student and teacher. Somewhere, there is a breakdown in this relationship when homework is not consistently completed. In seeing the lack of completion in homework, larger academic issues exist. It is beneficial for students to do homework in order to substantiate the trust that exists between students and their teachers.
Finally, I think that there is something about the feeling of accomplishment that students need to learn quickly. The ability to go to bed knowing that "a job has been done" involves a certain spirit of accomplishment. Homework helps to develop this feeling. When homework is done completely and thoroughly, students can say that they "did their part." This is a feeling that helps with whatever profession is chosen later on in life because the need to accomplish a particular task outside of the workplace setting is universal. The feeling of a "job having gotten done" is another benefit for homework that students can experience for themselves.