SpeedGrader is one of the great things about Canvas — it lets you mark up student work in the browser. You and the student both get access to the feedback. You can add rubrics (that make it even faster to grade work and give meaningful feedback). It’s good stuff.
But, sometimes, students will turn in work that can’t be annotated in the SpeedGrader — it can only be viewed or downloaded. So lame.
The trick is that SpeedGrader can only work with a few specific types of files: Word Documents and PDFs. To “force” students to only turn in those files, you can adjust your assignment settings. When you’re adding more details, look down to the advanced settings and try these out: