In the book, The Lion, the Witch and the Wardrobe, what could be the main theme or lesson I could teach to fourth graders to help them comprehend the story?
While The Lion can be analyzed at a complex level since it is, after all, the encapsulation of Lewis's apologetics, it is written for children with the expectation they will understand the theme and lesson he desires to communicate.
The fundamental theme involves Edmund, The White Witch, Aslan, Lucy, and Peter and Susan. The lesson is that temptations to turn from virtuous behavior occurs, but it is only with virtue that evil can be conquered. The fundamental theme is that though the power of evil is strong, the virtues of goodness are stronger and will be victorious in the end--with a little help from friends and Aslan!
The lesson incorporates Edmund because temptation to abandon virtue (or goodness) assaults us all at times. When we fail to hold to virtue, we can be forgiven and we can find a way to repair the harm done. The best way is to accept the spiritual impulses that Lewis attributes to Christianity; accept the gifts that affect victory; and fight bad influences with virtue. The main theme incorporates Aslan, the Narnians and the children because evil is very powerful and one person alone cannot stand up to it without gifts of virtues and help.
"Why, it is she who has got all of Narnia under her thumb. It's she that makes it always winter but never Christmas."
The very basic lesson taught in this story is that good triumphs over evil. The author was a biblical scholar and strong Christian. He wanted to write a story depicting Christian values, but in order to appeal to wide audience of children, chose to use fantasy in order to convey his message.