How to find a Stud behind Plasterboard

Watch how to find a stud wall using regular magnets, a pencil and a straight edge.
1-run the magnet along the wall until it sticks to a screw or nail head.
2-mark the location with a pencil.
3-search for another screw or nail above or below and mark it (usually 400mm away)
4- draw a line between and feel confident there is a stud behind that line