There are no due dates for discussions. However, students have access to a widget called "Work To Do" and is the equivalent of your "Quick Eval" widget- it shows them any upcoming or overdue course items with a due date. However, Discussions will NOT appear unless you give them an "end date." Go to the "Course Admin" tab in the blue navbar:

 

 

Scroll down and click on "Discussions" in the Communication section

 

 

Then click on the caret next to the discussion you want to edit dates for and then click "Edit Topic"

 

 

Then click on "Available Dates & Conditions" on the right side of the page 

 

 

Finally, enter an "End Date" and click the blue "Save and Close" button.

 

 

You can also create an event in the "Calendar" Tool that will show up in your students' calendar.