Read The Power of Un Storyline:
Everyone knows the almost magical power of the computer's "undo" command that can erase any mistake. Well, thanks to a device called the "under", middle-school student Gib Finney can do the same thing in real life. At first he thinks this is better than winning the lottery: he'll never fail another test, never lose another bet, never strike out in a ball-game again! But after a terrible accident, Gib must decide which events in a two-day period he needs to change to prevent disaster. Was the key when he and his friend Ash saw signs advertising a carnival? Or was it when he argued with Rainy Rogner about their experiment? Or perhaps when he shot a spitball at the math teacher? Gib soon learns that some things are more worthy of "inning" than others, and that some events may be impossible to change at all.Pages of The Power of Un :