The Purposes of Punishment in Schools

Education : Teaching students what IS right and wrong. It is high intellectual conceit to believe that a moral code can be so perfect that its mere explanation will ensure compliance. Actions against certain behaviour show them what the boundaries are.
Deterrence : Lowering the frequency of certain behaviours regardless of whether a student accepts the moral order. They merely wish to avoid the punishment they have seen meted out to others.
Rehabilitation : Behaviour modification works on any animal. Rehabilitation is a long term hope arising from deterrence: the student removes the behaviours from their repertoire, and absorbs them into their moral system.
Restoration : One technique of rehabilitation that focuses on moral teaching by attempting to repair the relationship or restore physical damage etc. It is an extreme view to believe that it can completely replace all other elements.
Honouring Values : Demonstrating that a system of codes is respected and actually implemented is crucial to the credibility of that system. e.g. disregard for the school uniform rules directly increases the frequency of a wide range of other misbehaviours as the "system" has lowered credibility.
Revenge, Retributive justice, or Retribution : If the system causes the wrongdoer pain, it is less likely that the victim (or the parent !) will try to exact their own retribution (e.g. "if he hits you, you bash him back !). Punishment systems act as a proxy for victim revenge so that individual vigilantism and revenge is reduced.
Incapacitation : Served by expulsion. If they are not present, they cannot break the rules. Necessary and underutilised strategy. Expulsion also has the advantage of powerfully complimenting deterrence. Only repeated and long term suspensions achieve this end. Usually suspension is directed at warning of the possibility of expulsion, encouraging parental reflection and action, and leading to an inquiry.

Stephen Digby