Movie trailers are supposed to tell the viewer “just enough.” Too much and the movie’s spoiled. Not enough and you might not care much about the story or characters. Trailers also have to keep the viewer's attention. This all holds true for reading, writing, and communicating. We want the reader to comprehend what we’ve written but we also want the reader to create meaning by asking questions, summing up sections small and large, making predictions, tapping into their own experience, and so on.