She did give a lesson one day, though, that has stuck with me ever since and helped me considerably in the writing of stories. She said that most folks think of stories in a linear fashion, with one event following another, but that's not a good way to write them. She suggested that a different diagram makes more sense, the plot daisy. The concept is simple, it's just an extension of Chekhov's gun on the mantle in act one that has to be used by act five, except that it's more than just the gun. Almost EVERYTHING that is introduced early has to come back later. That's why they are in the early part of the story in the first place.
So a plot daisy of the movie Gattaca might look something like this (my handwriting really does look this bad on a board):
At the center is whatever themes you want to ascribe to the story. The petals on daisy are plot points that are introduced early and come back later. An obvious one is labeled "right handed men" on the diagram. Early in the story, Vincent gives a urine sample to the doctor. The doc makes a comment about the quality of Vincent's "equipment." He says that he wished his parents had ordered one like that for him. At the time, this scene seems like a little joke (and a fairly crude one at that), although it goes along with the world building of a society heavily invested in genetic control. But it turns out this scene is critical to setting up the end. When Vincent has finally overcome all the obstacles involved in hiding his own inferior genetic makeup, he's ready to board the spaceship that will send him to Titan, but the company has instituted a new policy Vincent didn't anticipate, and he has to give one more urine sample before he leaves. He is only a few steps away from reaching his goal, but now he'll be discovered! He gives the urine sample to the doc while making a sort of speech justifying what he now knows is a failed attempt to escape his genetic destiny. The doctor tests the urine, which shows who Vincent really is. That should end the movie on a down note. Vincent failed. Instead, though, the doctor says, "For future reference, right handed men don't hold it with their left. Just one of those things. " He lets Vincent board the ship.
That scene wrenches every event in the story around. You realize that the doctor knew Vincent was a fake from the very beginning (the doctor has a son who isn't "everything they promised he would be," so he's sympathetic to Vincent's attempt).
It turns out, though, that there are numerous other petals on the daisy. The swimming competition between Vincent and Anton when they are young comes back. The comment Vincent makes about getting Irene's hair tested ("A breeze caught it," he says as he drops it), comes back later. The image of the incinerator/shower that opens the story also ends it. The scrubbing of body to get rid of the excess skin cells is repeated. Even Jerome's suicide is set up (he explains how his back was broken and then says, "If at first you don't succeed, try, try again").
In a literature class, we used to call a lot of this foreshadowing. Now, I see that whatever I want to be important in the end, I need to get in early. Everything on the first page is there to set up the last page.
When I get stuck on what's going on in my story, or when I'm revising to unify, I think of the plot daisy. It helps.