I agree the life cycle is good to help deal with life/death. we learned when a plant dies it goes back to the earth. It's good for a child to have a live plant then it dies - it is sad for the child. A tomatoe plant that dies at the end of the season is a good example. Maybe save the seeds for next year. Let them deal this little sadness helps them deal with bigger stuff later. Talk about how you feel when the plant dies.