In To Kill A Mockingbird, how does Harper Lee use parallelism and sequencing to explain a social commentary in chapters 6-8?

The term sequencing can refer to the series of events that make up a story. Therefore, in looking at parallelism as well as sequencing, one would look at the sequences of events that are parallel to each other in that they they share similarities. In Chapters 6 through 8 of To Kill a Mockingbird, we see some parallelism with respect to the series of events pertaining to the children's interactions with their neighbor Arthur (Boo) Radley, and author Harper Lee uses these parallel events to give a social commentary on prejudices and treatment of others.

In Chapter 6, when Jem, Dill, and Scout are chased off the Radleys' property by the sounds of Mr. Nathan Radley's shotgun, Jem gets his pants caught on the fence during the escape and must go back to retrieve them; however, he doesn't find them in the condition he would expect to find them. In Chapter 7, Jem confides to Scout that he found them "folded across the fence ... like they were expectin' me." Jem further informs Scout:

They'd been sewed up. Not like a lady sewed 'em, like somethin' I'd try to do. All crooked. (Ch. 7)

The condition of Jem's pants actually tells us quite a bit about Arthur's character. First, it tells us he is perfectly aware of what antics the children are up to. Second, since mending Jem's pants was an act of benevolence, the reader begins to learn Arthur is not the insane, dangerous person the children believe him to be as a result of prejudices; he is actually a kind and caring person who looks out for the children.

The benevolent act of mending Jem's pants in chapters 6 and 7 is paralleled by Arthur's further displays of kindness in chapters 7 and 8. In Chapter 7, Scout and Jem begin finding more items left in the knothole of the oak tree on the Radleys' property that they pass every day on their way home from school. Jem begins to realize that they are being left by Arthur and intended as gifts for the children, an act of kindness that becomes particularly evident when Scout and Jem find two soap dolls carved to look exactly like them. In Chapter 8, the children realize Arthur has carried out yet another benevolent act that parallels his other benevolent acts: he has sneaked up behind Scout and covered her shoulders with a woolen blanket while the two children stand out in the freezing cold early morning hours in front of the Radley gate, watching people try to mitigate the fire damage done to Miss Maudie's burning house.

This sequence of parallel events concerning Arthur's acts of benevolence help the children, especially Jem, realize Arthur has been misjudged. Jem realizes that Arthur is not the sort of person who would actually hurt the children and that Arthur is reaching out to the children in his own quiet way.