Well, not sure if "words of wisdom" from an Asian actor in a so-so movie constitutes a great advice, but as someone who taught in the public schools for 40 years, I'm going to say that at times, there were "bad" students.  Not bad as people, but bad in terms of valuing education.  There's only so much a teacher can do; only so many "tricks of the trade" we can use.  You hear about all these great stories like the math teacher Jaime Escalante in CA or the English teacher in "Dead Poet's Society" (both true stories), but I wouldn't say that's the norm.  Many students have poor home lives that affect their attitude towards school, and it's sometimes difficult for even the best teachers to overcome.  Regarding discipline, good teachers know to start off strict, then ease up a bit if the class allows.  Today's younger generation of teachers want to start out by being best buds to their students to "fit in" with them.  Before you can be their friend, you have to be their teacher.