Content is complete, but have to check formatting and I need a break (and dinner), so here's my quick take on what you want to do with Edmodo, but have no time to check it from both sides (Teacher's side and student's side-you did register as a student yourself and joined your class didn't you so you can see what they see?)
Set up a Quiz with Short Answers so they can free-write their responses. There are two time limits on quizzes: 1 for when it is due and 2 for how long they have to take the quiz. From memory, once they start they can't stop. It just times out. So set the quiz to be due in one week, but tell them once they start it, they have to finish it. The time pressure will probably do them good. Give them like 480 minutes so they have 8 hours to do it if they keep the window open.
With the short answer quiz you can give them a grade, though I think it has to be a number. No letter or P/F allowed (unless they've changed this). Still, Edmodo will record whether they have taken the quiz, turned in the quiz (or timed out), and will track the grade you gave them.
Edmodo Support is good, and if they can't do what you want, they may put it in as a feature request.
Assignments can do the same, but the students have to turn it in as Word Doc. and you can correct it and comment and grade within that interface, but it's awkward to use from both sides because the interface requires the students to log back in and check the PDF file that the interface creates so they can see the comments, but can't save them easily. I suggest the first route I mentioned. You might get better answers from Edmodo support or the users there.
Back to checking fonts, font sizes, TOC, and making sure the images didn't get mis-aligned when I added content.
42,903 words for those who are counting and 145 pages if the printing company can do it properly without messing up my content.