What are the discussion star ratings? Who sees them? How should I use them?
Star ratings are the stars you (as a teacher) see under each student post:
Who can see the star ratings? At this time only teachers can view the ratings that they give to a student.
Who can give star ratings? Only teachers can rate students with stars. Classmates can "like" each other's posts but can not give star ratings.
How should I use star ratings? The discussion star ratings are a great way to track what you have read and how you would grade that particular post for a student.
For more information on how and where to use star ratings see the article How do I view results in the new discussion interface?