Lessons for Writers: In the movie Back to the Future (1985), Doc says the phrase “If my calculations are correct” in reference to his time travel theory. In Iron Man (2008), Tony Stark says something like, “If my math is correct, and it always is,” in reference to the Arc Reactor technology. Screenwriter books teach that dialogue makes a character. This is a great example. That little tweak shows one key difference between those two characters. One is arrogant, the other is avuncular. Words matter.