They explained how, on a “green day”, he would earn two chips, on a “yellow day” he’d earn one chip, and then on a “red day” he’d earn nothing. One chip, in this circumstance, would “buy” the child one hour of game time.
Article source: https://www.huffingtonpost.co.uk/entry/consequences-dont-work-child-adhd_uk_6ad61002e4b061c2be448933