When we watch a movie, we enter a world created by the screenwriter. From the very first scene, events and characters begin to define a world, set in time and place, with implied values and social nuances. However, this initial world we see early on is only the first of two worlds that the screenwriter will create to tell the story.
The Ordinary World
This first world is called the Ordinary World. Think of it as a point of reference. It's "ordinary" in the sense that this is the world where our main character, the protagonist, lives. Screenwriters must define this early on and clearly because the story really begins when the protagonist accepts a challenge to leave the ordinary world for another -- the world of the story. But more about this second world in a moment.
The Ordinary World tells us where we are, and where the protagonist is. In E.T., for example, we meet the protagonist, the boy Eliot, on a typical night when he is being ignored by his older brother and his friends. No one pays attention to him. He's the younger brother who is in the way, and moreover he's in a house without a father. He's lonely. This is the Ordinary World of Eliot in E.T.
In The Graduate, we meet a recent college graduate who is bored. Who has no plans for the future. Who can say no more about the summer than that he hopes it is "different."
The Call to Action
Stories do not happen in ordinary worlds -- stories happen when choices and events propel the main character into a world far more exciting, different and challenging than the ordinary day-to-day experience represented by the Ordinary World.
The "call to action" is an early story moment when the protagonist makes a choice that will cause him or her to leave the Ordinary World and enter the world of the story, which is called the Extraordinary World. The reference point (to what makes it extra-ordinary) is always the "ordinary" experience of the main character.
Thus, Eliot plants candy to lure ET, the stranded alien, home, where he decides to keep him as a secret playmate. The boy is lonely no more -- and the world of the story becomes the world of Eliot with his new and unusual friend. And in The Graduate, the college man gets up the nerve to phone Mrs. Robinson, the first step to beginning an affair with her. He begins movement toward this affair with the phone call (the call to action), defining a world that is "different" indeed, his extra-ordinary world.
The Extraordinary World
So the world of the story, the extraordinary world, is entered by a definitive action by the protagonist. Sometimes, however, the protagonist may be more passive. In the wonderful satire Citizen Ruth, Ruth's action is to pray to God for help when she's in jail -- and along come the Baby Savers to rescue her and propel her into a world she's never known, where her bail gets paid and people seem to care for her.
The Extraordinary World is the world of the story. The first act ends when the protagonist has moved into this new world beyond the point of no return. The second act, which contains most of the conflict in any story, is firmly rooted in this world.
Define Your Two Worlds
Your writing task will progress with tighter focus if you have a firm grasp of these two worlds before you begin. Be able to define, clearly and simply, the three most important elements in the beginning of your story: the Ordinary World; the Call to Action; and the Extraordinary World of the story:
The Ordinary World, where the protagonist lives day-to-day, the starting point of the hero's journey;
The Call to Action, in which the protagonist responds to events by doing something, making a choice and performing an action, that will propel him toward the world of the story;
The Extraordinary World, the world of the story itself, where the hero is challenged and tested, and where he or she will win, usually, and become wiser for the struggle.
Clarity of these three elements of your story will get your screenplay off in focus and with clear efficiency.