Why?...

1. To make sure you have leaned the lessons the assignment was designed to teach
2. To improve your grade...actually you should be able to get a perfect grade on all assignments...eventually

When?

Do so as soon as possible.  Do not wait till late in the semester!

Note:   I EXPECT you to do your best the first time around and not take advantage of the resubmission process to be lazy.  Doing the homework assignments is where much of the learning takes place.  If you try to short-circuit this it WILL hurt your progress and your final grade.