How and why does Scout feel differently once the trial has started versus how she felt earlier while thinking about the incident at the jailhouse...

At the start of Chapter 16 of Harper Lee's To Kill a Mockingbird, once in bed after having faced a mob surrounding her father, Scout finally begins to understand that night's dangers and starts crying. Prior to that moment, she had only understood that her father was talking to a group of men in front of the jailhouse. Atticus's seemingly calm demeanor is partially responsible for her earlier naive interpretation. However, Mr. Underwood appearing...

At the start of Chapter 16 of Harper Lee's To Kill a Mockingbird, once in bed after having faced a mob surrounding her father, Scout finally begins to understand that night's dangers and starts crying. Prior to that moment, she had only understood that her father was talking to a group of men in front of the jailhouse. Atticus's seemingly calm demeanor is partially responsible for her earlier naive interpretation. However, Mr. Underwood appearing in his own window with his shotgun, saying he had Atticus covered all along, serves as a strong clue to young Scout that the mob was dangerous and that she had helped break up the mob. She explains her slow understanding of the danger of the situation in her following narration:

I was very tired, and was drifting into sleep when the memory of Atticus calmly folding his newspaper and pushing back his hat became Atticus standing in the middle of an empty waiting street, pushing up his glasses. (Ch. 16)

The next morning, Scout further expresses her understanding that the mob presented dangers by asking her father why Mr. Cunningham had "wanted to hurt [Atticus]" if he is a friend of the Finches.

Yet, as the day unfolds, Scout's fears for her father's safety evolve into fascination with the trial. One reason why her feelings evolve is because all of Maycomb county is fascinated by the trial. As Scout, Jem, and Dill stand in the Finches' front yard that morning, they watch all of Maycomb county head down their street into the town square. By the time the children make it into town themselves after lunch, they see that the town square is so full that there isn't a single space left at the "public hitching rail for another animal" and that "mules and wagons were parked under every available tree" (Ch. 16). Due to the size of the crowd gathered in the square, Scout describes it as a "gala occasion" (Ch. 16). In other words, the density and excitement of the crowd make it seem like the trial is a celebratory occasion, just like other "gala occasions," which made the children feel equally excited about the trial. Hence, Scout's feelings changed that morning from feelings of fear for her father's safety due to the trial to feelings of excitement that the trial was taking place. However, the feelings of fear soon return after the trial.