An option to preview the class as a student. The option could live in the class context menu. It would impersonate a "hidden" student account in your class that you could use to explore the class with.
If you've set up a class with multiple activities that you've completed while previewing your class you should have the option to 'reset' everything so you can do go through the class again. This is probably not going to be part of a version 1 of this feature though.