Here is what I've discovered about millennials and hashtags:
If I put "good job" or "insightful" or "brilliant" on a student's paper, they don't really care at all. However, if I put #rockedthistest, #vocabsuperstar, or #brilliant on these same papers, suddenly, they *love* it and are passing around their papers to show each other their hashtags.
So here's mine:
#stayrelevent