EASYI unfold a rectangleAnd feed it to this hungry box.A circle and a cylinderAre returned as a response.ANSWER: Soft-drink machineI unfold my rectangular dollar and stick it into a soft drink vending machine. A quarter and a can of soda are returned to me in response.INTERMEDIATEModel made of one of nineKept in classroom on a stand.I mimic a revolutionMoving nations with my hand.ANSWER: GlobeThe globe in a school classroom is a model of Earth, one of the nine planets. By spinning the globe with my hand -- "moving nations" -- I can mimic the revolutions of the Earth.DIFFICULTRough paperwork hereAnd abrasive conditionsEradicate flawsAnd help smooth transitions.ANSWER: SandpaperLots of rough "paper" work is necessary to smooth the abrasive conditions of splintered or jagged wood. Once the wood's flaws are eradicated, different pieces of lumber can be fitted together to create impeccably smooth surfaces -- such that no bumps or transitions are perceivable between the wooden pieces.