Trivium: The Classical Liberal Arts of Grammar, Logic, & Rhetoric is a book that explores linguistics. I like how the authors analyze alphabet letters, parts of speech, and patterns in language. In some ways, Trivium feels like a Linguistics 101 textbook. I liked how the book talked about ethics and reasoning, as well as the Socratic Method. If you have a passion for grammar or linguistics, it would be an interesting read. Though the book is detailed and suited for adults, I think that studious children as young as 11 may enjoy Trivium as well.
You can find Trivium here.