Katie defined "voracious reader". From the age of four, when I got home from work and she sat on my lap and read The Bob Books, she read everything. On car trips, she'd sit in the back of the minivan with a stack of books and be happy — until she ran out of books, anyway. And one of the (many) lasting images we have is of her sitting in the recliner in her room, largely buried in books, reading quietly to herself.
I've been an SF reader for a long time: I remember being in the library in Croton-on-Hudson and hearing some kid about my age trying to describe a book to the librarian as "about aliens, with a metal octopus on the cover". I suggested he meant War of the Worlds, and I was right. This was before we moved to Canada when I was 8, so I must have been reading SF for a while already.
Anyway, Robert A. Heinlein was always one of my favorites. In the 1950s, he wrote a series of books known as the "juveniles", which were targeted at teenagers (or "young adult readers", as we'd call them now). While of course horribly dated in many ways now, they're still eminently readable.
So when Katie was in maybe fifth grade, I started reading them to her. Not, of course, that she couldn't read them herself, but we enjoyed the time together, and I could answer (some of!) her many questions that the books raised.
Red Planet was one of her favorites: "Willis WARM!" was something she'd say when she got cold, although I suspect I was the only one who knew what she was on about.
SF has a tremendous range, from stories in the near future to "space opera" taking place centuries and light-years from here and now, but one basic form involves making an assumption and examining the changes that would result, on society and humanity: What if the South had won the Civil War (or Germany WWII)? What if a cheap, unlimited source of power (such as safe cold fusion) were found? What if we discovered a method of faster-than-light travel, and could thus visit other stars?
It's occurred to me recently that we're seeing some things happen in the world that are true SF events. For example, if tornadoes in the midwest become the norm, that will reshape where (or at least how) a huge number of Americans live: "tornado alley" might become largely empty, with farmers living in homes belowground, and the dispossessed squatting amongst the ruins of former towns. Or if the volcanic eruptions continue, air travel and thus our mobility will change. Railroads and steamships might return to ascendancy. And of course global warming in general may do things we can't even begin to anticipate.
My father told me many times that when he first had kids, he never realized that he would actually enjoy talking to them — that he had just kind of thought they'd always be kids and wouldn't have anything to contribute to adult conversations, and that he was pleasantly surprised to discover that he was wrong. He wasn't being rude or obnoxious; on the contrary, he was putting himself down, for having been so naïve.
I gotta say, we never felt this way about Katie. From the time she was little, she had interesting things to say and could synthesize concepts like someone far older, and we learned a lot from her.
So I keep wanting to discuss these SF events with her, because I know she'd have ideas about them that I don't, and that I'd come away with a new perspective.