Point scoring is an incredibly easy way of keeping students engaged and is also a clever way of managing behaviour.
In my experience with KS3 students (it may work with KS4 and KS5 too!), point scoring brings out the competitive nature in children and ensures that they do all they can to gain points and not lose points!
You can give points for good behaviour, working hard, good answers, etc. and remove points for disruption or talking in English when they should be talking in the target language.
Mr Winstanley's Bits and Pieces 