Should teacher be paid according to how much their students lear1

Should teacher be paid according to how much their students
learn?
I think it unreasonable that teachers are paid according to how much
their students learn. In fact, teachers should be paid according to
how much effort they pay. How much students learn cannot exactly
judge how much effort teachers pay. So teachers should not be paid
according to how much students learn.
Teaching and studying complement each other. If a teacher does
not teach his students anything, the students will learn nothing.
While if one student does not study carefully, no matter how much
his teacher teaches him, he will learn few. If the teacher is paid
according to how much that student learn, the teacher will be paid
few. It is unfair!
Therefore teachers should not be paid according to how much
students learn.
We suppose that teachers had been paid according to how much
students learn, how can we exactly judge how much students learn?
According to their grades, some students` grades may be A+`s, while
some others` grades are perhaps D`s. We will be according to which
grade to judge how much their teacher will be paid? Moreover, some
examinations are easy and some are difficult. The degree of difficulty
may affect students` grades directly. Thus it is not comprehensive to
judge how much students learn through examinations or any other
way. So it is unreasonable to pay teachers according to how much
students learn. Finally, if teachers are paid according to how much
stuents learn, teachers will try to teach students excessive knowledge
in order that they can be paid more money, thus the schoolwork would
be too heavy to be control by students. Owing to pressure, students
maybe lose their interest in study. In order to avoid that, teachers
should not be paid according to how much their students learn. All in
all, the means to pay teachers according to how much their students

learn is in order to make teachers more responsible to their students. I
admit that it is the positive effect. However, the three negative aspects
I have mentioned cannot be ignored. In a word, the disadvantages
outweigh the advantages. So teachers should not be paid according to
how much their students learn.