Beat sheets are to screenwriters what rulers and ISO specifications are to mechanical engineers. A reliable set of tools that help making everything work as expected.
When you learned to write essays in school, you may have been taught an outlining technique to help you organize the major points of an essay that you would flesh out later in your first draft.
Outlining is an excellent first step to most sorts of writing, and screenplays are no exception. Screenplays may need outlining more than other types of writing, as films and TV need clear structure.
In short, beat sheets are outlines with a twist
Beat sheets are a type of outline for a screenplay, named as each plot point is called a "beat." And it's these beats that will keep your screenplay moving along.
Beat sheets, especially those created as initial outlines, don't have to be highly detailed. If you don't know a character's name, the exact location or time of an event, just write what you have for the moment.
Create bulleted or numbered points for each major plot point. Start with establishing your main character's world.
Don't underestimate the role of setting; it contributes a great deal to the plausibility of your characters and plot points. Then state the action as you see it, in the order that your audience is supposed to view it. Write in flashbacks as the character sees them, not in their chronological order.
While "show, don't tell" governs most writing, as this is a pre-draft outline, it's OK to tell here. If a character is supposed to be selfish, charming or lazy, say so here, and use the draft to sort out how to show the character trait.
They also act as the Sergeant Hartman for "Gomer Pyle" writers
Beat sheets are a good way to get something on a page. Writers often have no shortage of ideas, but hesitate about development. With a beat sheet, you write what you have, which is often the germ of a story that needs only some nurturing to develop.
Once you have a full story arc written down, you can interrogate the outline to develop your draft.
- What does the main character look like?
- How does the main character get to the building across town in time to save her friend?
- How do you justify the time traveling paradox of Marty McFly... sorry everytime I think about this my brain hurts. But you got the point.
These and other questions will yield your first draft, and from there, you're only a couple edits away to something you can shoot.
Another approach: discovering the plot by applying a structure to it
You can also create a beat sheet from a less structured draft to help you spot where the story is going, which can be very useful in future drafts.
If you've written a highly detailed but vague draft, a beat sheet will pare the action and character development to its skeleton, allowing you to see what characters can be cut, and if you've lost the main story arc in a sea of details, a beat sheet can help you find it again.
Not every screenwriter uses beat sheets, but they are a useful tool in developing a screenplay with a strong structure.