The First Day of Class
One of the first items to cover in class is the criteria for the Participation Grade. A number of students believe that they have "participated" if they show up at some point in the class and occupy a seat.
I give them a written outline of the parameters to acquire a score of 100 each day for Participation. It is up to them to earn the following points:
25 points - Arriving on time
25 points - Arriving prepared for class (reading, homework, etc.)
25 points - Active contribution to class activities, exercises and discussions
25 points - Departing at the Official Dismissal (sneaking out is not permissible)
Once the student knows how these points will be earned - not penalized, their mindset changes, accordingly. Furthermore, they realize that the guidelines are very objective in nature and application.
The best evidence of success is when you hear them policing each other to produce to earn the daily points. That is a rewarding moment for the student and the teacher.