Conduct an FMEA of a pencil. Consider that the function is to make a black mark. Requirements could include that it is to make a mark, it marks a black color, and it intermittently fails to mark....

Conduct an FMEA of a pencil. Consider that the function is to make a black mark. Requirements could include that it is to make a mark, it marks a black color, and it intermittently fails to mark. Failure modes would then be that it makes no mark at all, mark is not black in color, and it marks intermittently.