Answer:
1) At the beginning of the story, Grey was really annoyed with his father because he gave him a strict condition which was if he doesn't pass his mathematics exam in school, he will not be allowed to join the basketball team. Greg was fed up with his father's constant lectures, this was the reason why he ran out of the house under the rain to an abandoned building.
2) At the end of the story Greg learned that he father meant well for him by asking him to read hard inorder to pass his exams, he learns to appreciate his father the more and also to valuable their relationship.
3) Greg learned about Lemon Brown's most priced treasure which was an harmonica that his son took with him to war to always remind him of his father. Lemon Brown's son valued the relationship he had with his father.
