Before I answer this question, I would like consider the merit of paying teachers' salary according to their students academic progress.   Those who agree with this idea might think the system is fair,  because employees in private companies gain their salary by their works and evaluating teachers by their students seems to be the same way as private companyfs workers.  However I absolutely disagree with this idea because of the following reasons.

 

  Firstly, teachers' job is not only teaching subjects, and evaluating by only their students academic ability do not solve unfairness.   Have you ever belonged some club in your high school or junior high school?  Teacher take responsibility to students' club activities.   Sometimes they take students some place for club activities.   When students cause troubles even outside school,  they go to police and apologize officer and those who injured or troubled by students. They also scold them to worn them not to happen again. 
 
  Secondly, even now equality of teacher's salary invite unfairness since these kind of works are not evaluated as the object to increase their salary and the amount of each teacher's work is different.   As for my mother, who is public junior high school teacher and has special work to scold students and going to apologize in many place, is very hard worker and everyday back home in late evening about at 10 p.m., although other teachers can usually finish their work at latest 7 p.m.  When big festival is hold near their school, they have to patrol to prevent their students from being involed in troubles.  Of course they cannot gain extra money by this patrol.  In private companies, such kind of works can be the object of paying extra money.   Donft you think that teachers sould gain extra money for their activity?   
 
  Now, hard working teachers like my mother have complaint but continue to doing this job in "volunteer".  All the teacher do not this activity.  Some teachers cannot even scold their students.  If teachers come to be decided their payment according to only their studnets academic ability, many teachers will try to rise their students' grade point average at any cost.  Therefore they might not do other activities than teaching students.  However those works never disappear after the new salary system is introduced.   Which teachers do this job?  Do you think it more unfair?

 

  I do not deny the importance of quality of lecture and this payment system's good effect of stimulating teachers' incentive.  In private school such kind of system is possible because private school can oust troublemakers and teachers can concentrate on teaching.  I don't know private schools situation because I went on public school from kindergarten to high school.  However in public school there are lots of teachers' works other than teaching students and evaluating teachers' works only their students academic ability invites serious unfairness.  Therefore I disagree with the statement.