Do students get alerts when I make comments in the comment box, the rubric, and the body of the paper? They often miss these conversations. I've resorted to hiding "secret code words" in my comments to make sure they read my feedback.
For comments left in the comment box, there is a submission comment notification that students control. The default for email is once a day, so it may be up to 24 hours before they get the notice. One of my early assignments is to go through and have them take a screen shot with that notification set to "right away." Students who use the mobile apps have that defaulted to on, which is almost immediately (the first message make take a while, but I've also seen students respond within minutes of me leaving a comment).
I do not remember seeing anything about comments left inside a rubric. There is a notification for when assignments are graded, but they just say that it's been graded (possibly containing the grade depending on user choice) and it's up to the student to go into Canvas to get more details. The notifications were set up to be short so they could be sent by text message, so there's not a lot of extra information in them.
I have never heard of comments left within a document (DocViewer) triggering a notification. Nor have I had any student ask me about comments I left until they got a grade for the assignment and they stumbled across the comments.
I will say that just because they get a notification or because it goes to their campus email address doesn't mean they read it. I remember one student who struggled for 12+ weeks in a course and frustrated me beyond belief because I kept on leaving detailed instructions about how to correct her work and nothing would ever change. She kept on making the same mistakes over and over despite my instructions otherwise. It wasn't until late in the semester that we figured out she hadn't been getting those messages.
It also may depend on how much they care -- I teach a general education statistics course and students just need a "D" to pass. Those who are happy with the minimum don't seem to respond until their grade is in danger and it's the last week or two of classes. Then all of a sudden, it's your fault for not reaching out to them when you have been all along.
Student notifications for DocViewer annotations was added earlier this year, as detailed in Ready Release Notes (2020-04-25). It is described in the supporting documentation as "Instructor Leaves an In-Line Annotation or Comment in Submission" and is included in the Submission Comments notification preference.
I've resorted to hiding "secret code words" in my comments to make sure they read my feedback.
I used to do exactly this in my courses, but for me it was a periodic surprise extra credit activity. In addition to the customary feedback, I'd add an annotation to each submission saying something like, "Send me a message through the Canvas Inbox by [date] confirming that you've read this comment and I will add 5 points to your score for this assignment."
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