first,define "good".do you want me to be good by whose standards?the society's?my parents'?the school's?or by my own?
it's natural for teenagers to rebel and to test the boundaries and to experiment.therefore,parents,school and the society as a whole should be more understanding and caring rather than ignoring the teenager's need,both emotional and physical.
in my opinion,screw "study hard".study what hard,if i may ask?not everyone is going to an engineer or a mathematician.kids have different talents and abilities.the problem with the expectations of the chinese society is that there is a single standard by which kids are measured,i.e.how they study in school.
in my book,being a good teenager is to experiment and explore the boundaries of life without stepping outside the bounds of law.remember,a good teenager does not mean a boring teenager.the best thing a teenager can do for their parents,school and the society is to find his own way and his own talent and abilities,so that they can be a significant contributor to society after the teenage years.