The Great Brain was written by John Dennis Fitzgerald (1906-1988) and is set in the small town of Adenville, Utah, between 1896 and 1898. The narrator is the youngest of 3 boys in a Catholic family in a predominantly Mormon area of Utah. John Dennis Fitzgerald, also called JD, tells the story of his oldest brother Sven and parents but the main focus is the middle brother Tom who has the "Great Brain."
I haven't seen it but The Great Brain was made into a movie in 1978, with the main character played by Jimmy Osmond.
The book gives a look at life in a much simpler time and place along with all that goes with it. Kids play "Kick the Can" and similar games, have lots of chores, share a single school room and teacher among grades and so on.
Tom, The Great Brain, is always scheming to make money. For example, he charges kids a penny each to watch the first indoor toilet installed in the town in their house.
The Great Brain figures out schemes to enrich himself but also manages to greatly help others and the community. He saves some kids trapped in a cave, helps a Jewish travelling salesman and prevents a kid who lost his leg to gangrene from committing suicide.
It's an entertaining book to listen to while driving and I'm sure reading it would be just as fun. Nothing heavy, but interesting. I am looking forward to the 1969 sequel called More Adventures of the Great Brain.