Ender's Game (Ender Wiggins Saga) by Orson Scott Card

running to the cameras would be wrong.
      He walked the short bridge to the door in the shuttle. He noticed that the wall to his right was carpeted like a floor. That was where the disorientation began. The moment he thought of the wall as a floor, he began to feel like he was walking on a wall. He got to the ladder, and noticed that the vertical surface behind it was also carpeted. I am climbing up the floor. Hand over hand, step by step.
      And then, for fun, he pretended that he was climbing down the wall. He did it almost instantly in his mind, convinced himself against the best evidence of gravity. He found himself gripping the seat tightly, even though gravity pulled him firmly against it.
      The other boys were bouncing on their seats a little, poking and pushing, shouting. Ender carefully found the straps, figured out how they fit together to hold him at crotch, waist, and shoulders. He imagined the ship dangling upside down on the undersurface of the Earth, the giant fingers of gravity holding them firmly in place. But we will slip away, he thought. We are going to fall off this planet.
      He did not know its significance at the time. Later, though, he would remember that it was even before he left Earth that he first thought of it as a planet, like any other, not particularly his own.
      "Oh, already figured it out," said Graff. He was standing on the ladder.
      "Coming with us?" Ender asked.
      "I don't usually come down for recruiting," Graff said. "I'm kind of in charge there. Administrator of the School. Like a principal. They told me I had to come back or I'd lose my job." He smiled.
      Ender smiled back. He felt comfortable with Graff. Graff was good. And he was principal of the Battle School. Ender relaxed a little. He would have a friend there.
      The other boys were belted in place, those who hadn't done as Ender did. Then they waited for an hour while a TV at the front of the shuttle introduced them to shuttle flight, the history of space flight, and their possible future with the great starships of the I.F. Very boring stuff. Ender had seen such films before.
      Except that he had not been belted into a seat inside the shuttle. Hanging upside down from the belly of Earth.
      The launch wasn't bad. A little scary. Some jolting, a few moments of panic that this might be the first failed launch in the history of the shuttle. The movies hadn't made it plain how much violence you could experience, lying on your back in a soft chair.
      Then it was over, and he really was hanging by the straps, no gravity anywhere.
      But because he had already reoriented himself, he was not surprised when Graff came up the ladder backward, as if he were climbing down to the front of the shuttle. Nor did it bother him when Graff hooked his feet under a rung and pushed off with his hands, so that suddenly he swung upright, as if this were an ordinary airplane.
      The reorientations were too much for some. One boy gagged; Ender understood then why they had been forbidden to eat anything for twenty hours before the launch. Vomit in null gravity wouldn't be fun.
      But for Ender, Graff's gravity game was fun, And he carried it further, imagining that Graff was actually hanging upside down from the center aisle, and then picturing him sticking straight out from a side wall. Gravity could go any which way. However I want it to go. I can make Graff stand on his head and he doesn't even know it.
      "What do you think is so funny, Wiggin?”
      Graff's voice was sharp and angry. What did I do wrong, thought Ender. Did I laugh out loud?
      "I asked you a question, soldier!" barked Graff.
      Oh yes. This is the beginning of the training routine. Ender had seen some military shows on TV, and they always shouted a lot at the beginning of training before the soldier and the officer became good friends.
      "Yes sir," Ender said.
      "Well answer it, then!”
      "I thought of you hanging upside down by your feet. I thought