The following version of the book was used to create this study guide: Clements, Andrew. Frindle. Simon and Schuster Children's Publishing, New York, NY, 1998. Kindle AZW file.

Nick Allen is a student at Lincoln Elementary School. He is excellent at distracting teachers, an especially useful skill when teachers are about to make homework assignments. In third and fourth grade, he got away with this repeatedly, as well as a few other behaviors. As Nick heads into fifth grade, he knows that some things will change this year. One of the reasons is that all the students at Lincoln Elementary School have Mrs. Granger for language arts. Nick is there on the final class of the first day. While other classes were spent getting books and catching up with friends, Mrs. Granger gives a vocabulary test and launches into lessons. Nick knows dictionaries are the cornerstone of Mrs. Granger's lessons. He asks a leading question about the origin of dictionaries to distract her from the homework assignment he senses. Instead of answering, Mrs. Granger decides Nick has to write a report on the origin of dictionaries. Then, she makes the regular homework assignment as well. The next day, Nick manages to keep his report going for almost the entire class period, but Mrs. Granger crams her entire lesson into the few minutes remaining. Nick has a legitimate question. He asks Mrs. Granger who decides what words will make up language. Mrs. Granger says each of us make that decision in our daily choices of words.

That afternoon, Nick finally understands Mrs. Granger's message, and he impetuously comes up with the word “frindle” instead of pen. Over the next week, he and some friends launch the word in a local shop so that the clerk soon understands the word frindle. They begin to use it at school, but Mrs. Granger is not happy with their misuse of the English language. Nick and other students refuse to back down and continue to use the word, despite being repeatedly held after school. Soon, the local newspaper picks up the story, followed by a national news agency. Other national shows and magazines write about Nick and his word.

A man in Westfield, Bud Lawrence, sees an opportunity and begins making pens with the word frindle on them. Though local demand dwindles quickly, national and then international interest picks up. Soon, Bud has created an entire franchise, but his lawyers say he needs Nick's formal permission before going farther. Nick's father signs a contract, and the money pours into a trust fund for Nick. Over the rest of the year, Nick finds himself worried that he will begin some other movement that gets out of hand, but Mrs. Granger urges him to never lose his desire to do things.

When Nick turns 21, he receives the money from his trust and is shocked at the wealth. Mrs. Granger sends him a package that same year, a decade after he was in her fifth grade class. The package has a dictionary that includes the word "frindle" as an entry and a letter Mrs. Granger wrote when Nick was in her class. From that letter, Nick realizes Mrs. Granger had hoped he would succeed. Nick uses some of his money to set up a one million-dollar scholarship in Mrs. Granger's name. He then sends her a pen, engraved with an inscription that acknowledges her right to call this “object” anything she chooses.