Story grammar is the various elements that come together to build the story. It includes setting, characters, problem, solution. The plot, climax and suspense can also be a part of the story grammar.
Any child struggling with comprehension will benefit from using the framework of story grammar. A story map is the visual representation of the key elements thus identified. Using guiding questions like "When did the story happen?", "Where did it happen?", "Who are the people in the story?", "What happens to the main character?", "What's the problem?", "What do they do next?", and "How did the story end?" to populate the fields will be helpful in reinforcing the understanding/ comprehension.
For a detailed read on what else can help develop comprehension skills, follow this link
Here are a few simple formats for the story maps that you can use. The simple one is being able to tell the beginning, middle and ending to a story by writing or drawing pictures. The other two are step further with opportunity for detailing the setting and characters of the story.
A example of a story map for the popular story of Red Riding Hood to provide some inspiration, if you need any.