One thing that Mitchell seems to be quite good at doing is bringing in bits of Jason’s thoughts that the reader can well relate to from past experience:
Teachers’re always using that "in your own words." I hate that. Authors knit their sentences tight. It’s their job. Why make us unpick them, just to put it back together more shonkily? How’re you s’posed to say Kapellmeister if you can’t say Kapellmeister? (p. 210)
These is an underlying poignancy about Jason and how he deals with popularity among his peers, his interest in girls, and his concern about his parents’ fighting. These are all things that many of us have experienced in one way or another. There is that one big problem of his stuttering that runs throughout the novel tying them all together. The speech impediment may indeed be a metaphor for adolescence.