You can add a rubric to a graded discussion to help students understand expectations for the discussion and how you intend to score their replies. Occasionally, rubrics are added to quizzes when you have an outcome inside of the rubric that you would like to use for alignment purposes.  In addition to quizzes, rubrics can also be added to graded discussions and assignments.

Note: You cannot use a rubric for grading in quizzes, since quiz scores are calculated based on the number of points assigned to each quiz question.