It has happened. Someone close to us has died and I had to explain death to my 4 1/2 year old.
My grandmother died a couple years ago, but to be honest, she lived 800 miles away and I hadn't seen her in years. I felt sad when she died, but she was old, she was tired and sick. I had spoken to her a few times before she died...I had closure. And Willow did not need to really know much more about it. I mentioned the passing in an abstraction and she went back to playing.
Today, we found out a good friend, a friend who came by our house often enough and spent time with Willow often enough...well, he died suddenly last week, and we just found out.
And I had to explain death to her. Finally. I could not put it off. Not being religious, I have to be careful not to couch things in too stark of terms...life cycles seem to work well. All I know is that she said "I want _____ back." Me too, hon. Me too.