[Assignments] Allow immediate feedback in assignments

[akoch]

It would be nice if students could access an answer key immediate upon submission of an assignment to assess their work.

This can already be done in quizzes, but the quiz function has other limitations when using it for formative homework assignments. 

[truskell]

Can we do something like add a "Solution" button to assignments?  Then we can add a solution to an assignment similar to the way we can add a rubric.  The "Solution" can either have its own reveal date, or be automatically set as visible after the due date.  Faculty could always see the solution, and students could see it when the solution visibility date arrives.

[jmfelder]

Adding a Solution/Key button to an assignment would really help my students get feedback immediately.  This way, we could enable it when we have a solution and they would always know where to find the key.  

[timothy_maw]

I had an instructor asking me about having a solution key available within Canvas yesterday. This would really help instructors with grading assignments, let alone the feedback that could be available for students.