Tape the plastic sheet to a table top.
Put on the rubber gloves.
Darken the room as much as possible.
Hold the large iron pot or pan by its insulating handle and rub the pan vigorously to and fro on the plastic sheet.
Holding the fork firmly in the other hand, bring its prongs slowly near the rim. When the gap between pot and fork is small, a tiny spark should jump across (A darker room will help you see the spark more clearly).