^^^Seconded. There are other ways to handle the subject that don't require lying. Something like: "All living things are constellations of atoms. When we die, the constellations lose their shape, but the atoms stay the same; they just move around. Some go into the water, some the air, some into other living things. So in a way when we die, parts of us become all kinds of different things and go to many different places."
Or this line from the comic book adaptation of Jonny Quest: "All I know is that in the end, we're energy. And energy can't be destroyed, it can only change from one form into another."