Warning Stop/Go cards - behaviour management

Behaviour management cards given with no discussion or eye contact - just placed on desk (after explaining how used at beginning of lesson!) to ensure emphasis is placed on student to make the right decision and minimise teacher wasted time spent managing low level behaviour and not teaching. Front and back of designs to be laminated together.
Stop card - Has a 'stop' sign on the front & sentence on the back asking students to change their behaviour and return the card to the teacher after 5 minutes to explain what they were doing that was unacceptable and how they have changed their behaviour as a consequence.
Go card - Has a 'go' sign on the front - given to students who have corrected their behaviour to ensure positive praise and feedback when behaviour has changed (I explain that receiving 3 of these means a positive phone call home!).
Really successful use - students HATE to get the 'stop' cards but also know that it is a reminder/warning about their behaviour & they are keen to apologise, change their behaviour & give the card back to you as soon as possible!