they are jerks
In the mob scene, Scout recognizes her friend Walter Cunningham's father, Mr Cunningham as being part of the mob. A mob is about anonymity, and Scout recognizing an individual breaks that.
In Harper Lee's novel, To Kill a Mockingbird Jem tells Scout that he fears, their father, Atticus will get in trouble. Jem fears this because he thinks the group of men were apart of a mob that was upset about Atticus helping Tom Robinson.
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.
The children, Scout and Jem, intervened and approached the mob at the jail where Atticus was guarding Tom Robinson. Scout's innocent conversation with Mr. Cunningham, one of the mob members, and her recognition of other men in the mob led them to disperse and retreat. Her presence humanized the situation and prevented any violence from occurring.
Mr. Underwood does with a shotgun, vthen Scout, Jem and Dill arrive.
Atticus doesn't hear Jem and Scout hollering because he is preoccupied with talking to the mob of men outside the jail. He is focused on diffusing the tense situation and protecting Tom Robinson from harm.
At the Finch house, trouble begins when Scout and Jem are harassed by Bob Ewell following the trial, putting them in harm's way. At the jail, trouble starts when a mob arrives to lynch Tom Robinson, but is diffused by Scout's innocent conversation with Mr. Cunningham.
In Chapter 15 of "To Kill a Mockingbird," Scout and Jem make the faulty assumption that Atticus needs protection from the lynch mob that shows up at the jail. They underestimate Atticus's courage and resourcefulness, as he is able to defuse the situation without their help. They also assume that the men in the mob are irredeemably racist and not capable of reason or empathy.
As Jem's eyes become opened to the hatred of the world and he takes his first steps into manhood, Jem learns the roots of racism in Maycomb, Alabama. He shows signs of his development in the Lynch Mob Scene.
The affect scout had on the mob is she made them more kind hearted.
In Harper Lee's novel, To Kill a Mockingbird Jem tells Scout that he fears, their father, Atticus will get in trouble. Jem fears this because he thinks the group of men were apart of a mob that was upset about Atticus helping Tom Robinson.
Jem recounts that after Atticus shot the mad dog, Tim Johnson, in one shot, Calpurnia takes them to the colored church where they are welcomed by the community. Jem also tells Scout about how Atticus faced down a mob at the jail to protect Tom Robinson. Scout missed these events due to being at the Finch house.