A Wrinkle In Time, by Madeleine L'Engle I probably read it in fourth or fifth grade, not too many years after it was published. It was definitely the first science fiction novel I ever read. It wasn't until many years later that I saw how foundational to my worldview it was that my first SF book had a female protagonist. I was going to give a few other examples of truly life-changing works (LOTR, Dune, Neuromancer),…
Introduced me to the world of fantasy and science fiction, which has been a source of enjoyment since then. I don't know if it pushed me towards my current occupation as a SWE, but it sure didn't hurt.