Quote 10
I realized then that I didn't understand anything. I read all the books I could. (4.40)
After listening to a conversation between her parents and her grandparents, Marji realizes that she's simply too young to understand the adults' conversation. She decides to read, but we have to wonder if that's an adequate replacement for life experience.
Quote 11
"Don't you know that when [parents] keep saying someone is on a trip it really means he is dead?" (7.7)
Marji is at an awkward social stage where she understands that her parents are kind of lying to her, but she still doesn't understand that it isn't socially acceptable to tell a friend that her dad is dead. Emily Post would not approve.
Quote 12
If I wanted to be friends with 14-year-olds, I had to do it. (15.7)
Marji has reached an age where she wants to have older friends. The problem is that she's not mature enough to pretend to act like a fourteen-year-old, and she ends up making a lot of mistakes. Though maybe that's what growing up is about.