Direct, Stilted
The Great Brain doesn't beat around the bush. J.D. gets right to the point in his narration, describing whatever's happening in a play by play. Even when he pauses to add his own commentary on events, he doesn't make readers guess about what he's getting at—dude comes right out and says it.
In conversation, the characters rarely use contractions, which sometimes makes their speech sound stiff and more formal than life in Adenville actually is. Check out the following passage for an example:
She looked at us and smiled. "What have you two boys on your minds?" she asked.
"Why is Mr. Harvey digging a hole in our backyard?" Tom asked.
"It is the cesspool for the water closet your father ordered from Sears Roebuck," Mamma answered. (1.26-28)
In case we ever forget we're hanging out in 1896, the dialogue makes sure to remind us with its proper style… even when talking about toilets.