It's Hard to Explain about Death to Children

Jeff's grandmother passed away last week and we went to the funeral which was a "Celebration of Her Life".  Since we've been home I've been bombarded with questions from Katy about death and heaven.  Questions about: why do we put the body in the ground since she went to heaven? or if she went to heaven how come we could see her? or when we die will we be able to see in heaven, since our eyes are in our body?.  How do you explain that it is their soul that goes to heaven and their body stays behind to a five year old?  And have them understand.  Katy also told me just a little while ago, "I'm glad I got to see what Daddy's grandma looked like, she was cute.".