providing grade points when students leave class prematurally
To keep students from leaving and to cure the late arrival
a good point is to have some quiz exercise in class
leave some points in grade book for this
In my class I lecture and demo one day, the next day students cook what I showed them the day before.
I always start the cooking day off with a quiz. If students are late they don't get to take the quiz and loose points. It has worked well for me over the past years, very few late students. In fact most students arrive early and study notes and ask each other questions.
I think that it is an excellent idea to take points or grades away from students who are constantly late. It will discipline them to be more responsible.