Explaining what "Death" Is

How do I communicate "death" to kids? Esp to BJ?

When we explained that Daddy has to fly off to Sarawak because aunty passed away, we did not know how to tell him. Chilli Padi commented that BJ does not understand what death is. We simply told him that "Aunty died. Daddy will not see aunty again. No more aunty. Daddy sad sad."

Ren commented that he kinda knew it, because he got moody, and sad as well.

The only experience he could associate this death with, is kakak leaving.

There's difference between death and leaving. But, in some instances, they may look the same.