To comment or post a followup question to a Q&A post, please click within the text box just beneath the post that reads, "Compose a new followup discussion."
All post contributors, as well as any others following the post, will be notified of a new followup. Only instructors and the original author can edit a particular followup, but anyone can comment on it or reply to it.
When a new followup is posted, it will automatically be set to Unresolved, and an icon reading 1 unresolved followup will display beneath the post in your Q&A feed, as seen below.
Individual instructors and students can resolve a followup by selecting Resolved just above the followup, as seen below. Any user is able to mark the followup as Unresolved again should they have additional questions.
To reply to a followup, simply type your response into the text box beneath the followup itself.