Reader Marcia Hall just posted an excellent summary, "6 Reasons Your Child Refuses to Do Homework." I urge all parents of school-age children to read this.
Homework makes a critical contribution to effective learning. First, it imposes memory rehearsal soon after new learning is presented. This promotes consolidation into long-term memory. Second, homework causes students to think about new learning, and thinking itself is the best form of memory rehearsal.
Unfortunately, too many teachers make homework "drill and kill." To be most effective, homework should require students to think about the learning in new ways and contexts. For example, if they learn some history facts during the day, the homework needs to require them to make an application of those facts, such as relating it to lessons for today's world or evaluating the history to preceding events or those that followed later.
Another kind of homework that is useful is as preparation for what is going to be presented soon in class. This use of homework can help stimulate interest. In any case, it gives students some factual background that will help them get more out of what will be covered in class.
If you or the teachers disapprove of homework, please re-think your position. Homework of the right kind is a time-tested major contributor to learning.