My children are 14 and 11. We have had any number of discussions with them about what death is and what might happen after death (my wife and I do not agree on this, and the kids also have different opinions). They have seen me bawling uncontrollably after I went to visit my band leader and they took us to see his body. He had died only an hour or so before.
My advice is that you do the same. Talk about death as you see it and think about it. Share your feelings. Don’t hide anything. Share your feelings. I think the best way to teach them is by showing them what you feel, and how you handle it. If you are stoic about it or try to hide it from them, that’s how they will think it must be done.
I have, for better or for worse, always shared my feelings and fears about issues like these with my children. I don’t do it in a way that asks them to care for me. I am just sharing.
When my mother-in-law died, my son started weeping at the funeral. My daughter kept things inside, as did her mother and I. People feel what they feel. If they feel nothing, they feel nothing. If they want to be emotional, they should be emotional.
One of my closest friends dies this past year. We offered the kids a chance to go to the funeral, but they decided not to because it would be too sad. It was very sad and my wife and I were weeping as they lowered his coffin into the grave. Something about the symbolism of that is way stronger than I ever would have believed. It reminds us, I think, that death is very permanent.
If there are any rituals you might have—saying a prayer (even atheists can say prayers—it doesn’t have to be to a god) or pulling out pictures or calling relatives—whatever, share them with her. Even if she was 5, I would think she was old enough to participate. If she asks questions, answer as best you can. But I don’t think you need to keep anything—what’s happening to him, what you fear, what you feel, or whatever—from her.