The Student Discussion feature is available at the list level, and at the individual citation level (video tutorials below).
Student Discussion View
Click to expand:
Instructors and students can post comments in the student discussion thread.
If you decide you don't want to have the student discussion feature on your list, you can easily disable it.
1) Click on the ellipsis at the top right of your reading list
2) Click on Configure list discussions and select Hide student discussion thread.