The book Dear Mr. Henshaw is organized chronologically. The story is told exclusively through the writings of the main character, Leigh Botts. In the beginning, these writings appear in the form of letters written to Leigh's favorite author, Mr. Henshaw; Leigh writes the first letter in the second grade. As the story progresses, Mr. Henshaw encourages Leigh to keep a diary, and entries to this diary, as well as some of Leigh's school writing assignments, are included as well.
The author's creative use of this form of organization serves a couple of purposes. First of all, because the story is told from Leigh's first-person perspective through his writings, the reader is given insight into his thoughts, feelings, and reactions to the pivotal events in his life. This personal approach allows the reader to really understand the character as he grows through the years.
The second purpose served by the author's method of organization is that it allows the reader to experience first-hand Leigh's emotional and intellectual growth. The first letter, which was written when Leigh was in second grade, is very brief and filled with spelling errors. As Leigh progresses through the years, his grammar and spelling improve age-appropriately, and his letters and entries get longer. By the time he is in sixth grade, Leigh writes quite well, and his entries start to take the form of real narrative. In addition to his academic growth, Leigh's emotional growth is also evident in his writings, as he shows a greater ability to see things from perspectives other than his own, and to deal with the difficulties in his life as he gets older. By telling the story through Leigh's words as he grows from childhood to early adolescence, the author allows the reader to experience that time of growth with him.