The children's initial reaction to Tom's guilty verdict is one of hurt, anger, and disbelief. They have sat through the entire trial, and they know that Atticus has established Tom's innocence. Jem asks Atticus:

How could they do it, how could they?

Lee also makes clear that the sense of injustice the children experienced after hearing the verdict was not simply a passing feeling before they moved on to other interests. It sticks with them, changing the way they view the world. Scout, for instance, quickly sees the disconnect between what Miss Gates teaches at school and Miss Gates's personal behavior. Miss Gates talks at length in the classroom about the evils of Hitler's persecution of the Jews. She calls the Jews good and very religious people who contribute to their society. She agrees with Scout's definition of democracy as

Equal rights for all, special privileges for none.

Yet Scout knows that Miss Gates doesn't apply this principle when it comes to the religious, hard working Black people in her own community. Instead, she supports persecution and injustice when she approves the conviction of the innocent Tom Robinson. This so bothers Scout that she goes to Jem and says she saw Miss Gates,

“coming out of the courthouse … talking with Miss Stephanie Crawford. I heard her say it’s time somebody taught ‘em a lesson, they were gettin’ way above themselves... Jem, how can you hate Hitler so bad an’ then turn around and be ugly about folks right at home—”

Jem was suddenly furious. He leaped off the bed, grabbed me by the collar and shook me. “I never wanta hear about that courthouse again, ever, ever, you hear me? You hear me?"

Jem's response shows that he also has not forgotten the unfair verdict, which is still a raw and disillusioning wound. Both children are struggling to understand why adults in their community can so quickly abandon their principles when their self interest is at stake and be so blind to their own moral failings.

Scout's narration is surprisingly emotionally detached during her description of the Tom Robinson trial. There are aspects of the trial which are beyond her understanding, which explains part of her straight forward approach, but she is savvy enough to recognize that Atticus's attempt to sway the jury to the real truth is going to be ultimately unsuccessful. The return of the jury had "a dreamlike quality" to it: They moved "like underwater swimmers," and Judge Taylor's commanding voice seemed "tiny."

I saw something only a lawyer's child can be expected to see, could be expected to watch for, and it was like watching Atticus walk into the street, raise a rifle and pull the trigger, but watching all the time knowing that the gun was empty.
     A jury never looks at a defendant it has convicted, and when this jury came in, not one of them looked at Tom Robinson.

Jem had been much more emotional during the trial, and he was convinced that Atticus had proven Tom innocent. At one point he exclaimed to Scout that "We've got him." But when the trial was over, 

     It was Jem's turn to cry. His face was streaked with angry tears as we made our way through the cheerful crowd. "It ain't right," he muttered...
     "It ain't right, Atticus," said Jem.
     "No son, it's not right."