You may enter a Yahoo! contribution (either an original contribution [Messages: Post], or a comment [Reply] on someone else's contribution) any number of times. Contributions might be new information, correction of someone else's information, interpretation, argumentation, etc. Always put your real name in the Message part of the posting. I need to know who you are in order to give you a grade for what you do.
There is NO fixed ending date for the process of discussing and commenting, except the Midterm exam date. But, obviously, the earlier you post the more likely it is that you will say something new and worthwhile.
Your own personal grade for this element of the course (as with "classroom participation") depends on the number of contributions you make and their quality. Quality includes "literary quality". This assignment is part of the writing requirement for an upper-division GE course. So think about and plan what you write before you send something. Please remember to use courtesy in dealing with your fellow students. Everyone will be reading what you write. Inappropriate postings will be removed by the Instructor, and no credit will be given for them.
