I'm working on my new book, The Art of Teaching Sunday School, and in it there will be a chapter on Children's Messages that are developmentally and academically appropriate for specific ages. For example, when you have a lot of young children, object lessons are not really the best way to go. You'll do better if you do something repetitive, a cute song, or a simple rhyme.
Tomorrow is All Saints Day. We're talking about all the saints who have gone before us and we have a number of pretty young children, so I suggested to my pastor that he hand out little paper trumpets or kazoos and turn the whole thing into a celebration that when we die we go to be with Jesus.
You can add a short Bible verse too, and let the kids walk around a bit playing their horns and shouting the verse or something along the lines of "In God's house there's a room for me!" or, "When we die we go to heaven!" This way, whenever they play the horn or kazoo, hopefully, they'll remember what they said too!