Marking in primary schools used to be done with a red pen or whatever colour happened to be closest at hand. I've even marked in pencil once, but most of that marking was rubbed out by the children. What's happened now however has been steadily creeping in over the last few years - red pen is seen as bad, a terrible colour to mark with. Children view it as negative even if their work is correct. Red is now a banned marking colour in many primary schools across the land and has been replaced with a plethora of colour coded marking schemes, all followed to the colour due to the ridiculous nature of some primary school marking policies.