Probably the single most stolen item of all BRGS. But they have so many uses other than just writing valuable teaching information, such as...
The standard whiteboard marker has been superseded by the far greater Interactive whiteboard marker. These are not stolen items as they are guarded like gold by all teachers, especially the maths department. Mrs Chapman is known to have at least 10 of these ultimate teaching pens, most teachers only have two.
Mrs Stevenson-Jones had a lot of whiteboard pens, but they can now only be found on… ledges, Room 5's projector, the top shelves of the beaker cupboards, on top of the whiteboard itself etc.
Many of the science teachers are very proud of their slogan ‘Conservation of Whiteboard Pens: the number of pens at the start of the lesson = number of pens at the end of the lesson’. It appears to not have any bearing of the situation however.