This is a very familiar story to those who grew up in the church, but if you have the privilege of teaching children who have never heard it before - it is dynamite.
I used a combination of flannel-graph and homemade action figures to teach the story.
The main point of this lesson is that Elijah is trying to bring the people to a decision - If the LORD be God, worship him, but if Baal be God, then worship him. They were wavering between two opinions and his job was to confront them with the truth and help them come to the right commitment. Their devotion was divided. God wants our undivided devotion.