Hello @cchapman ...
I tested this out on my own iPad, and as long as you are using the rubric for assignment grading, the student should see the rubric displayed on the "Grade" tab when they navigate to the assignment within the app...as shown here:
Hope this helps!!!
Were you able to find an answer to your question? I am going to go ahead and mark this question as answered because there hasn't been any more activity in a while so I assume that you have the information that you need. If you still have a question about this or if you have information that you would like to share with the community, by all means, please do come back and leave a comment.