It was her eyes that did it. They were dark gray, and if she turned them on full power, they could make you feel like a speck of dust.”
-- Narrator (2 )

Importance: This is the description of Mrs. Granger and one of the ways she exerted iron control over her students.

He looked over his notes again and again – the first English dictionary, the growth of the English language, William Shakespeare, words from French and German, new words, old words, new inventions, Anglo-Saxon words, Latin and Greek roots, American English – it all became a big jumble in his mind.”
-- Narrator (5 )

Importance: This takes place as Nick is preparing to give his report in Mrs. Granger's class on the second day of school. Mrs. Granger is undoubtedly expecting only a very basic report, but Nick manages to keep talking for almost the entire class period, which is his way of rebelling against the assignment.

Then while...
-- Narrator (chapter 9)