In case you didn't see it or get a chance to read it yet, I recommend reading Ginny Mooney's article "The Cross Still Draws."
Ginny gives great talking points on how to explain to people, regardless of age, about the power of the Cross!
As for the Lady Gaga video she mentions in her article -- it's not for the faint of heart, but it is something that's permeated our culture. Perhaps even something that your kids have seen. So it's good to be aware of it.