Because he wants people to realize not everyone is perfect.
That Tom Robinson got shot when trying to escape
To show that Tom is honest. Tom answers atticus' question honestly and admits he's been in trouble before, therefore it shows he's honest & will answer truthfully when he's questioned about Mayella Ewelle.
The African American folks bring food to Atticus as a gesture of gratitude and support for his defense of Tom Robinson in the trial. Atticus appreciates their generosity and humble demeanor, but he also recognizes the inequality and racial tensions that exist in their society.
That her father is a drunk and has beaten her before.
The news that Tom Robinson was killed while trying to escape from prison. This is during chapters 25-27 - After the Court Case
He was a mad dog. Atticus shot him and then Scout and Jem found out that their dad was "One-Shot Finch." The dog represents racism and Atticus shooting him represents Atticus trying to bring down racism. The fact that Atticus was a "little to the right" alludes to the fact that Atticus will not win the case with Tom Robinson.
Atticus went downtown one evening to protect Tom Robinson from a potential mob that planned to harm him while he was in jail. He knew there was a threat to Tom's safety, so he wanted to make sure that nothing happened to him.
Show that they don't. Many men are quite caring and responsible, and are often the ones that stop trouble, sometimes before it happens. "Men only bring trouble" is a bad stereotype and could never be remotely applied even in the worst neighbourhoods.
Atticus informs his family that Tom Robinson was shot and killed while trying to escape from prison. He shares the news that the prison guards shot Tom multiple times, resulting in his death. Atticus expresses his sadness and disbelief at the outcome.
Jem didn't do anything, he just brought scout to the jail while the mob was there. Scout showed the mob that Atticus helps everyone. The mob wanted Tom Robinson, but they would have to go through Atticus (hurting him in the process most likely) to get to Tom. If Jem didn't bring Scout, Atticus would have been injured in some way.
I know the answer to the first part of the question. He compares the mob to wild animals. So it took an eight-year-old child to bring 'em to their senses, didn't it?" ... "That proves something-- that a gang of wild animals can be stopped, simply because they're still human." .. Sorry if it wasn't much help ):
She had come to tell Atticus (who was cross-examining a witness) that his children, Jem and Scout, were missing. they were actually in the courthouse, watching the trial from upstairs in the colored gallery.