Have you ever been annoyed by the child that knows what happens in the text of the Bible lesson and wants to blurt it out, ruining the surprise ending you had in mind for the other children? You may just encourage a budding Bible teacher if you invite the child to join in the giving of the lesson!
Allow the child to come to where you are presenting the lesson and ask him to be ready to explain parts of the story. When you come to a visual that gives some of the story facts, allow the child to explain just the part that is shown.
This will allow you to be in control of his desire to tell the story. He will be quiet, waiting in anticipation, until you cue him. And he will be participating in the lesson, which means he will get to know it even better. And you will be sharing the joys of Bible teaching with him, allowing him to share in God's work and perhaps encouraging him to become a Bible teacher somewhere down the road. Who knows? He may even end up being your assistant teacher!