Frindle centers around an epic battle of wills between Mrs. Granger, a teacher of language arts, and one of her students, Nick Allen. The battle is based around words, how we use them, and where they come from.
Mrs. Granger loves the dictionary; in fact, as Nick tells us, she almost worships it. She believes that dictionaries are the ultimate source of vocabulary and that her students should regularly learn new words by consulting a good dictionary, which, as far as she's concerned, every home should have.
Nick couldn't disagree more. He has no particular use for dictionaries. That's because he gets his vocabulary from reading, and as he reads an awful lot of books, he has quite a large vocabulary for his age. A boy who enjoys words and knows how to use them effectively, Nick doesn't really see much point in raiding the dictionary to find new words.
When Nick comes across a new word that he doesn't know, he asks his brother or dad what it means. If they know the answer, they'll tell him. But Mrs. Granger doesn't. She wants Nick and her other students to find out what words mean by looking them up in her beloved dictionary.