The student, whose name is not being released because of his age, hollowed out a Game Boy and filled it with gunpowder, Livingston police said.
But when the student bragged about his invention, another student called Crime Stoppers to report the device, police said.
The Polk County school was evacuated briefly Thursday afternoon while officials searched for the student and the bomb. He was arrested on a school bus headed to a track meet, and the bomb was rendered harmless.
Police said the boy could be charged with carrying a prohibited weapon into a school zone, a second degree felony.

http://www.chron.com/cs/CDA/ssistory.mpl/metropolitan/2412280