Plotting by Theme, Part 1: Process
A great definition of theme, at least in regard to some stories, is the lesson that the protagonist learns as a result of his or her experiences.
According to this definition, the story's main character, or protagonist, is the one who learns a lesson. When writing your story, it's important to remember not to get off track and let a secondary character learn the lesson meant for the protagonist. Although such a mistake may seem unlikely, it can happen all too easily.
Ask yourself, What lesson do I want my protagonist to learn? If the main character is to learn something, he or she must first lack the understanding to be acquired. This point may seem obvious, but, again, it's easy to start off on the wrong foot by suggesting or showing (or even stating directly) that the protagonist already knows the very thing that he or she needs to learn and then forget, as you write the story, that you did so.
Make the lesson something specific, not general. For example, “I want my protagonist to learn to be a better person” is too broad, but “I want my protagonist to learn to be be humble” is fairly specific.
Think of your lesson as having three parts: (1) ignorance, (2) experience, and (3) lesson (understanding). As your story unfolds, your protagonist will undergo a transformation from ignorance to understanding as he or she has various experiences.
With this in mind, after establishing what lesson you want your protagonist to learn, identify the experiences that will teach your main character this lesson. Then determine how you will show that your protagonist has learned this lesson.
You might come up with something like this:
At the start of your story, Pete, your protagonist, is arrogant (he has not learned to be humble). He thinks that his Secret Santa, Kelly, whose parents are poor, has bought him a cheap gift, especially when he sees how small the gift-wrapped package is. He tells his friend Billy that he wishes a different student had been his Secret Santa.
In the middle of your story, Pete is humbled, first, by having Jimmy, a popular classmate, scorn the gift that Pete, as Jimmy's Secret Santa, buys for Jimmy, and, again, when Kelly gives him a better and more thoughtful gift than Pete had anticipated receiving.
At the end of your story, Pete has learned to be humble. He confesses his former arrogance to Kelly and apologizes to her, before thanking Jimmy for inadvertently calling to Pete's attention Pete's own arrogance.
Plotting by Theme, Part 2: Example
As we've seen, using theme to plot a story is an effective approach to writing fiction. Let's look at how a famous Hollywood movie uses this approach.
The movie The Wizard of Oz is a good example of theme as understood in this manner. At the outset of the film, the main character, Dorothy Gale, is shown as being disappointed in—and, I might add, unappreciative of—her home with her Aunt Em and Uncle Henry.
They live on a farm in Kansas, where everything seems dull and gray to Dorothy. While it's true that she doesn't have any friends her own age, except for her dog Toto, and it's true that her aunt and uncle, like their farmhands, seem to have little time for her, it's also apparent that Dorothy, like many children her age, is self-absorbed. She doesn't seem to recognize or appreciate the hard work that the adults have to do to keep food on the table and clothes on their backs. They're living during the Great Depression. Times are hard for everyone, but, at least, they have one another.
For Dorothy, though, life on the farm with her aunt and uncle is not enough. She dreams—literally, as it turns out—of a place “somewhere over the rainbow,” where all is bright and beautiful and life is full of excitement and adventure.
A circus fortuneteller, Professor Marvel, who waits out the approaching storm in his wagon, assures Dorothy, who visits him after running away from home, that her aunt and uncle love her a great deal and are worried about her safety.
But his assurances come too late: although Dorothy hurries home, she is caught in the storm and, taking refuge with Toto inside the family's farmhouse, she is carried off to Oz by a cyclone.
As soon as she arrives in Oz, Dorothy becomes homesick. She wants to return to Kansas, to her farm, to Aunt Em and Uncle Henry, to her home. The experiences she has while she's in Oz make her more and more homesick. She meets a brainless Scarecrow, a heartless Tin Man, and a cowardly lion. She learns what it would be like to have no brain, no heart, and no “nerve.”
But she also learns to depend on and to act on behalf of herself. She becomes independent, resourceful, courageous. She defends the Scarecrow and her other companions, and she stands up to both the Wicked Witch and the Wizard of Oz himself. She matures.
At the end of the story, her experiences in Oz have taught her a valuable lesson, which she shares with her aunt and uncle: “There's no place like home.” The self-absorbed girl who disliked her home and failed to appreciate her relatives now enjoys her home and values Aunt Em and Uncle Henry.