I've been in the book business since 1989.  Perhaps none of you are aware of this, but Bradbury's Fahrenheit 451 is constantly, year in and year out, on the required reading list in schools.  Every year thousands of, maybe tens of thousands of, possibly more, kids are exposed to his work.  Other writers of science fiction who are on reading lists are C.S. Lewis and Ursula LeGuin.  Recently, Orson Scott Card's Ender's Game has gotten on the list to the point that there is now what is called a Young Adult edition that is shelved in the children's section of the store.  I don't know if kids remember these authors but they sure know who wrote Twilight, Eragon, and the Percy Jackson and Harry Potter adventures.