Theory:

A story map is a flow chart that represents the main events of a story. It helps us to remember the main events of a story in a pictorial format. Since it is in the form of a picture, it is easier to remember the main events of the story.
For example, the story of "When the trees walked" may be put in a story map, as follows:
 
Story map.PNG
 
Writing the summary after the story map is easy, as all the main points are highlighted. With the given information, paragraphs will be formed to make the summary.
 
The summary can be formed this way:
 
The author's grandfather built a bungalow in Dehradun and planted trees around the house. Not content with just that, he also planted trees in the jungle beyond the riverbed. Once they saw a small rocky island, which had a mango plant sprung up due to the magical touch of the monsoon rains. They decided to plant many young trees. Then the Second World War started, and the family moved to England. After several years the author returned to his town and visited the rocky island, which had turned into a spectacular paradise. All the trees that they had planted had multiplied, and he realized that his grandfather's dream of the trees walking again, had come true!