Ender’s Game by Orson Scott Card
Ender
hasn’t really had much of a life yet; he’s six, after all. He does go
to school, though, where he’s bullied for being a Third, all the while
being tested for something he doesn’t know, but knows it’s important.
Turns out he passed, when his siblings didn’t. And his brother Peter
resents him for it. When Ender gets to the Battle School to train to
fight the buggers, an alien race that has already attacked humankind
twice, he is again hated on for being so intelligent, but he excels, and
everyone
notices. In the Battle Room, Ender is a genius, knowing how to defeat
his enemies even though his commander won’t let him even step inside the
room. Nobody else seems to understand how to think in zero gravity...