Andrew Clements' Frindle is told by a third-person omniscient narrator. Third-person narrators stand outside of the story and relay the action as it occurs. Very rarely are we ever given any clues in the story as to who the third-person narrator is, and we can often see the third-person narrator as the author. In the case of Frindle, we are not given any clues as to the identity of the narrator. All we know is that the narrator is someone who knows a great deal about nearly every character, enough to be able to get inside the heads of more than one character. Someone who knows that much about the characters is someone who has done a great deal of thinking and researching about the characters—someone like the author himself.
Third-person narrators can easily be recognized because they use pronouns like he or she to describe all the characters, whereas a first-person narrator will use I or me when describing their own thoughts or actions. We are able to recognize the third-person narrator within the very first sentences of Frindle:
Was Nick a troublemaker? Hard to say. One thing's for sure: Nick Allen had plenty of ideas, and he knew what to do with them (5).
Since, in these few sentences, the narrator directly uses Nick's name and the pronoun he, we can tell the story is being told by a third-person narrator. A first-person narrator doesn't have to be the protagonist, but he or she usually is.
An omniscient narrator is a narrator who sees and knows all, as opposed to a third-person limited narrator who only focuses on and gets inside the head of one single character. While we do see the narrator of the story primarily get inside Nick's head, we also see the narrator get inside the head of a few other characters, including Judy Morgan, the reporter for The Westfield Gazette. We see the narrator get inside the head of the reporter when the narrator comments that her story on planting trees could wait because the story of kids being rebellious at the elementary school is much more important:
The trees could wait. This thing at the elementary school sounded like a real story (51).
Beyond getting into multiple characters' heads, the narrator knows much more about the characters than just someone like Nick would if he were observing. For example, the narrator knows Mrs. Granger lives in a "tidy little house," drives a "pale blue car," and never sweats (10). The narrator is also present when Nick begins spending his fortune, reads the letter from Mrs. Granger, and when Mrs. Granger opens her package from Nick. Since the narrator sees all and knows most all, it's impossible for the narrator to be an actual character from the story. At best, we can suppose the narrator is the author himself.