Common Core Standards
Grade 4
Writing W.4.3.A
Orient the reader by establishing a situation and introducing a narrator and/or characters; organize an event sequence that unfolds naturally.
When reading fiction, we need to know a few things right out of the gate in order to get a good grasp on what's happening. Considering this, it's important that your students start introducing characters and dropping us into a situation.
Also, continue encouraging students to develop their narrative and "see" their stories as they write them, so everything "unfolds naturally."