Homework is practice of a skill, and serves as much-needed repetition and review. HOWEVER, homework should NOT be assigned unless the student is able to do it on his own (thus the concept has been taught REALLY well).

Why grade homework?

If you're grading homework for accuracy and including scores in the gradebook, it's an assessment grade. If it's an assessment grade, how accurate is it? Did the student cheat, copy from someone else, not do it at all, get help from a parent, or did the parent do the work? If the student truly did the work on his own, shouldn't she be allowed to make and learn from mistakes on practice without penalty? So, why grade homework for accuracy?

If you're grading homework for effort, for example, "done or not done," then you're grading for behavior and not achievement. Effort and participation grades distort achievement. They don't accurately reflect what a student knows and is able to do. So, why grade homework for effort?