It totally depends on the age of the child, I think. When animals on our farm died when my child was a preteen we just said they had died and left it at that. When my son was eleven and his father died I had him write a letter to his dad telling him what he would like to say to him.

Now my son is nineteen and we talk frankly about death. He knows I want to be an organ donor if I can and have my body donated to a medical school. I told him if he didn't want to come view my body that was fine just remember me as I lived. It is inevitable and I hope it is a long way off but I want to prepare him for the natural course of life ending in death.