Our favourite was to give the apprentice one end of a ball of string and asked to hold it against an equipment rack (or other suitable point) to measure the length of a cable run... in the days before digits were everywhere, Video connecting cables were timed to a nanosecond or so; call it a foot in a line that might be half a mile or more long.
Of course, once round the corner and out of sight, the string would be tied to a convenient door handle...
Biting the hand that feeds IT
