One thing that was painfully obvious when I was still teaching was that as each year passed there was less and less overlap between the cultural frame of reference of the students and my frame of reference. I don't mean that I ceased to be hip to whatever music they were listening to, but the increasing degree to which basic current events for me were ancient history for them.
Members of this year's incoming college freshman class were born in 1992. They were six when Bill Clinton's penis almost destroyed the world. As a historian friend occasionally says, she doesn't yet have to explain who Monica Lewinsky is, but she will soon...