First - I've marked this as both middle grade and YA fiction, bc I can't really decide where to place it: the main character is 12, but some of the concepts might be a little bit advanced for some middle grade readers (Did you also happen to notice that I shelved it on "books I am too dumb for? So don't take that personally.)Other than that, I really enjoyed this book which, as I said, covers some pretty abstract and complicated issues - time travel, friendship, adolescence, growing up, being part of a family/neighborhood/community - but somehow does it in the most straightforward and simple of ways. So that, even when you're not 100% sure you've got the complicated stuff, it doesn't matter because the simple stuff is more important anyways. Miranda, the main character in this book, has been best friends with the boy who lives downstairs, Sal. Always: since their mothers met in the lobby while they were both still small enough to sleep in car seats and swaddling. Only then one day, they're walking home from school together and a boy they don't know punches Sal in the face and walks away, and Sal ends their friendship. Or at least that's how Miranda sees it. Over the course of the (short) novel, she learns a lot about what's real, what she assumes is real, and how much you just make up because you don't know any better. Which doesn't even mention that she starts receiving cryptic notes from the 'future', or that she starts building relationships with new friends, or that her mother is about to go on the $20,000 Pyramid (the setting of the book is 1978-9, btw, in case you were wondering on the Pyramid's low jackpot number. We all know it grew later, but in 79, poor Dick Clark could only afford the $20,000, I suppose.)One of my most favorite parts of the book is the relationship between Miranda and her mother's boyfriend, Richard. He's not even a major part of the story, really, which makes it all the more important to me that Rebecca Stead didn't go out of her way to make Richard some sort of perverted skeeve or clueless doofus: He's just a regular guy, that dates Miranda's mother and doesn't see Miranda as somebody he's got to win over or misplace or become best buddies with - they get along fine enough, nobody seems to see the other party as a huge threat (which I hate, hate, hate in fiction about divorce, middle grade fiction particularly... if only because I knew lots of kids whose parents got divorced/remarried when we hit 6-8th grade and, for the most part? Their step-parents were ordinary, nice people.) Maybe it's because it's been going on a while by the time the story starts, maybe it's because he doesn't really try to control her or boss her around in the story; maybe it's because he isn't the main focus of her life (and neither is her mother, which, when I was twelve I know my parents were not), but for whatever reason, I liked that there was an affection between them that wasn't cloying or creepy, but just a sense of: 'ok: this is how it is' that I really appreciated. Additional pluses were short chapter lengths (and overall story length, which mean I can tempt my nephew with this for his next book report); the homage and honor paid to A Wrinkle in Time; and minor spoiler having realistically portrayed friendships, particularly female friendships: When Miranda realizes that Julia, a girl she thinks is kind of a snob and has been treating like a snob for most of their school life together, actually isn't the caricature she's created in her mind, she takes steps to fix things. Every young girl I know who's made such a mistake - when she's realized it - has felt like dirt and then tried to make it better. Mean Girls may do exist, but the majority of the girls I know are just trying to figure it out, not make enemies for no reason.