Ten checkers are stacked up by father and child. All the checkers are red except the fourth from the bottom. Stand another checker on edge, and pressing down with your finger, snap it so that it shoots rapidly on edge against the stack of checkers. Instead of the stack falling or the bottom checker going out, the one black checker, fourth from the bottom, flies from the stack while the other checkers do not fall.
Note: If unusually thick checkers are used, it is possible that the third checker from the bottom may be the one ejected. This can be determined by experiment, and the black checker should be placed at the proper position.