What a great way to teach on death, before it comes real close to your young ones! I did something very similar. When both my girls were very young I started teaching about things dying as there were to be many deaths coming up in our family soon and I wanted them prepared as much as they could be at their young ages.
There were no dying animals to be rescued, so... I did what I thought was the next best thing. When they brought me wild flowers that died the next day, we talked about life, death, dying. When the balloon no longer stayed high up in the room we talked about the process of dying and death when the balloon "died" and laid on the floor. My children have attended many days at hospitals (thanks to not being in public school...they were able to be part of the process not just the conclusion at a funeral), and many funerals, but they already had a concept of death because they had seen it played out in life before it came close to them.
When the deaths in the family came, we were then able to discuss with the children the beauty of heaven and life after death; opposed to explaining death and it's process. They then had some hope and not only despair.
