A dramatic convention is a set of rules which the participant or audience and actor are both engaged in, they are usually set up within the drama/play and are used throughout all drama and theatre. An example of a convention which everyone knows is when the lights go down in a theatre, everyone goes quiet as the show is about to start, or in a panto-mime the audience responses to "Oh no he isn't" etc.
In drama, such as teacher in role it is things such as the use of costume to indicate the change from teacher to character.
