Fiction:
1) The Sherlock Holmes Canon - https://en.wikipedia.org/wiki/Canon_of_Sherlock_Holmes
My first exposure was through "The Case Book of Sherlock Holmes" and it made such a huge impression on me with its focus on the use of step-by-step logical reasoning to solving problems that in a sense it taught me to "think rationally" in real life. I then set about acquiring the complete canon and have read them all so many times that i can quote entire dialogues/passages from memory. The language used is also elegant and beautiful with lots of memorable phrases/quotes/quips etc. Every kid should be asked to read the complete canon and then discuss takeaways from them.
2) Charles Dickens - Started with Oliver Twist, Great Expectations
These books (read the unabridged versions) were my introduction to the "Human Condition/Human Values" faced by people from different economic strata. His books span different genres but always end with a positive note. The writing style is beautiful with a healthy dose of Melodrama, Humour, Vivid descriptions etc. which draw you in and keep you engaged. Here is a good essay on his narrative technique - https://www.lsj.org/literature/essays/dickens
Non-Fiction:
1) Physics for Entertainment by Yakov Perelman - You can get scans of all his and other Soviet authors books at - https://mirtitles.org/
In those days (80s in India) American/British books were generally not available and too costly but Soviet books were easily available and very affordable. My dad bought me this 2-vol set and that motivated my lifelong interest in Science. An example: I was enamoured of the protagonist in "The Invisible Man" by H.G.Wells but Perelman uses it as a scientific case study and shows that instead of being a most powerful man (because he is invisible) he would be the most powerless/pathetic man. Read the book to find out why :-) It also kick-started my collection of Soviet Science books eg. "Science For Everyone" and "Little Mathematics Library" series. Teachers/Students should take a look at these books and use them productively in the classroom/self-study. They are concise, precise with no fluff and a high s/n ratio.