It's funny when we revisit things from our childhood. I was probably 10 or 11 when I read A Wrinkle In Time, I think I remember owning the book. I had a shelf of paperbacks that I constantly read and reread like crazy. Roald Dahl, Katherine Patterson, Louis Lowry, Beverly Cleary, Judy Blume. There were a few babysitter's club books but mom discouraged those, she compared them to fast food, except with literature. Mom picked out plenty of wonderful books that I loved so I sort of listened to her on that one.
Anyway, the only thing I remembered about A Wrinkle In Time is that there's a bit where the children get beamed to a two-dimensional world, where everything would just be flat and you could only see lines, and they feel very squished. I really liked that. Sure enough I was right, it's in there, but it's like one page, so it's funny that it stuck with me so much.
It has a lot of Christian themes in it, which surprised me because I don't remember those at all. I guess when I was 10 Christianity was sort of a given, nothing worth noticing, but two-dimensional worlds were amazing.
Interestingly, The Fountainhead and A Wrinkle In Time both portray a sort of hell as a place where we all have to conform and fit into society without questioning authority. That's where the similarities end, though, both authors have very different ideas about how you break out of that sort of hell. There's the objectivist philosophy, where the way to break out is to be a naturally born super genius. The Christian philosophy says you can break out by loving your fellow man, and we don't just say that for syrupy cheesy huggy reasons. It's because love is complicated, and it can't be understood by The Machine so it breaks it down. Think of Ghandi.
Anyway it's a kids' chapter book, it's got big print and simple dialog and the story is timeless and you'll love it. You have to read it, and if it's been 20 years since you read it you have to read it again.