The more we know the Scripture surrounding our assigned reading, the better we can convey its meaning to our listeners. We must not only have the passage we're reading down pat, but also what leads up to and follows it.
In the reading from the Book of Jonah (3:1-5, 10), for example, without knowing the parts of the book about Jonah's hostility toward the Ninevites and his reluctance to warn them that their city could be destroyed, we'd likely give our listeners the impression that he was happily following God's instructions with no problem.
Without knowing the whole story, our interpretation of a reading can be similar to catching a scene in the middle of a movie and taking it out of context because we didn't know the before and after parts.
Like the private investigator who questions only one of several witnesses to a crime and draws distorted conclusions from his lack of knowledge, we also can risk conveying too narrow of an interpretation when we only read isolated parts of Scripture.
Always strive to dig into "the rest of the story."