There are actually two different quotes here with two different contexts.
The first quote comes from the middle of chapter 9. In this context Scout is interacting with Francis. Scout and Francis are talking about what they each received for Christmas. Scout was excited, because she received an air rifle. She politely asked Francis what he received. He responded by saying that he got exactly what he wanted.
“Just what I asked for,” he said. Francis had requested a pair of knee-pants, a red leather booksack, five shirts and an untied bow tie.
Right after this, the quote that you asked about comes up. In short, Scout is saying that Francis is the most boring person she has ever met. Here is the full quote:
Talking to Francis gave me the sensation of settling slowly to the bottom of the ocean. He was the most boring child I ever met.
The second quote comes right at the beginning chapter 9. Here Scout asks Atticus if what the children were saying at school was true. Here is the dialogue:
“Do you defend niggers, Atticus?” I asked him that evening.
“Of course I do. Don’t say nigger, Scout. That’s common."
“‘s what everybody at school says."
“From now on it’ll be everybody less one—"
“Well if you don’t want me to grow up talkin‘ that way, why do you send me to school?”
Scout did not like school. From the beginning of the year, it seems that nothing went her way. Now that the children were also making fun of what her father was doing, she liked school less. In light of this, she did not want to go; Atticus would have nothing of it, no matter how much Scout pleaded, cajoled, or protested.