What is Mrs. Granger's battle cry?

Mrs. Granger's famous battle cry, one that all her students past and present know all too well, is "Look it up! That's why we have the dictionary." Mrs. Granger teaches her class that words gain their meaning from how we use them. That inspires the mischievous Nick to use a completely made-up word (the "frindle" of the title). But of course that's not what Mrs. Granger means at all, as Nick knows full well.
Words and their meanings evolve and develop over time, gradually entering into daily use. Mrs. Granger regards the dictionary not as a book of laws and rules that govern our language, but rather as a record of the words we use to describe the world around us. So when someone wants to find out the origin or meaning of a word in everyday use, they need to look it up in a dictionary, because that's what the dictionary is there for, as she asserts.