In Parliament last week, Education Minister (Schools) Ng Chee Meng made the point that it is the quality of teachers that is important, not just class size, when it comes to student achievement (Reducing class sizes can benefit students: Leon Perera; Nov 8).

Certainly, there is some merit to the argument.

There are numerous published journal articles in many countries that suggest this.

But if this really is the case, is the Ministry of Education's (MOE's) efforts to increase teacher quality headed in the right direction?

How does MOE assess "teacher quality"? There is no objective measurement as to how well teachers teach and how great an impact they have on their students.

The only obvious yardstick would be how well their students perform academically, and a system that uses that as the main criterion is flawed.

The best way for a teacher to ensure long-term improvement in a student's achievement is to instil the desire to learn and improve, such that students are driven to improve themselves, even without their teachers' guidance.

And yet, if the performance of our teachers is tied to the current academic performance of their students, it is unlikely that such an approach, which sacrifices some of the students' short-term growth to ensure greater long-term growth, would be adopted.

After all, a teacher's pay and career prospects are tied to performance, and valuing teachers based on their students' current performance motivates them to teach in a manner that emphasises rote memorisation - a method that can certainly bring great short-term results.

Thus, I believe that if we wish to improve student performance as a whole in Singapore, how MOE determines teacher quality becomes the most essential factor.

Ngiam Heng Kee