They were both a bit scared when I said we were going to start a fire, but I explained that it would be a small fire and near the sink where we had a bowl of water ready to go. Above is our video. As you can see/hear, it was a big hit with my daughters who demanded an encore performance. Of course I obliged!
You're starting a fire in this experiment, so obviously be prepared. Also, be careful using your fingers to hold the gum wrapper to the battery terminals. The wrapper gets hot very quickly and you can burn yourself. As long as you're careful, this is an awesome experiment/demo to show your kids!!!