Scout and Jem were trying to find if Boo was alive, if so then get him to come out. This is getting the reader aware of the curiosity of the kids that would cause their further actions
Scout and another kid at school got into a fight over him calling her dad a "nigger lover" because of taking Tom Robinson's case. This creates the tension and aggression rising for Scout and her family
This is where a group of out-of-town farmers pulled up to come and take tom before the trail with Atticus waiting for them at the jail. This shows that the aggression got so bad that they were about to hurt Tom before the trial started and they would hurt Atticus to get to him.
Tom's case was found guilty in the courtroom by the jury of all white farmers. This shows how prejudice the town is to believe a white girl over a black man.
Scout and Jem were walking home from Scout's pageant where she was a ham hock. As they were walking they were jumped by Bob Ewell, who tried to kill them. This shows how the same white man the town believed over a black man just tried to kill kids.
After the attack, Jem was brought home by a mysterious man, who Scout just realized was Boo Radley. This helped bring the novel to a full circle by showing Scout that her prejudice about Boo Radley was wrong and that he is actually a nice person.