If I unpublish an assignment, can students still see the assignment? I want to import past assignments from a previous course but unpublish them and then publish them as needed.
You're good! Unpublished assignments cannot be seen by the students.
You'll want to note that once a student submits an assignment in the current course (regardless of whether it was a new assignment or an import from another location), you can't unpublish it. That is not a problem with the work-flow you described, just a warning that you'll want to make sure you get all of them unpublished before some over-zealous student starts taking them.
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