No relationship between class size and learning outcomes: OECD

No relationship between class size and learning outcomes said oecd singapore

The of seeking is coded into our people’s DNA. This phenomenon has little to do with the efficacy of school teachers. It has got more to do with the mentality of wanting to be ahead, to have an edge over others. This, in itself, is not a bad thing because that is how Singapore has survived and prospered – by being at least one step ahead of others. The pertinent question is whether chasing academic grades gives you an edge over others. Ultimately, what will get you ahead is a thirst for learning, critical thinking and problem-solving skill, the ability to work as a team and good communication skill.  

Workers’ Party Jamus Lim’s claim that tutors are responsible for the impressive test scores of local students rankles for the simple fact that it’s an insultingly superficial sweep of our education system.

As they say, the devil is in the details. While Jamus has made the comparison on class size and teacher-student ratios, he has omitted to compare Singapore’s performance with the performance of the same countries he brought up in his speech.

For that, let’s delve into the PISA results conducted by OECD as mentioned by both WP Jamus Lim and PSP Hazel. We shall investigate the 3 nations named specifically by Jamus Lim in comparison to Singapore’s results.

In the latest study:



Teacher-Student Ratio













The teacher-student ratio for Singapore is comparable to OECD countries like Austria and better than Denmark.

When we compare the results across the respective disciplines, the difference in performance becomes startling:


























OECD PISA 2018 Results

If smaller class size means better outcomes, then one would expect students from Denmark, Austria and Luxembourg to outperform Singapore students. But this is not the case. As you can see from the tables, despite having the lowest teacher-student ratio, Luxembourg lags far behind Singapore in performance, falling below even the OECD average in all categories. Singapore, on the other hand, blazes ahead of all the countries mentioned by Jamus, performing far above the average.

Small classes do not necessarily create high-performing education systems

Reducing class size is very appealing. The natural thinking is that with a smaller class, the teacher is able to give more time to each child/student. This is true to some extent, especially with very young children. Overall the evidence of the effects of differences in class size on student performance is weak according to an OECD publication on ‘Education at a glance’.

The Pisa international tables suggest that small class sizes do not necessarily create high-performing education systems. In fact, Andreas Schleicher who is Director for Education and Skills, and Special Advisor on Education Policy to the Secretary-General at the OECD in Paris which runs the Pisa Research, says:

“Everywhere, teachers, parents and policy-makers favour small classes as the key to better and more personalised education… And yet, Pisa results show no relationship between class size and learning outcomes, neither within nor across countries.”

Efficacy of teachers matters more than class size

The quality of teachers matters because the education system cannot be better than the quality of teachers.

The countries at the top of the Pisa tables spend their money in their professionals, says Schleicher. They prioritise spending money on better quality teachers – for example by offering competitive salaries, investing in professional development and managing teacher workload – rather than on making classrooms smaller. Which is what Singapore is doing.

As Education Minister Lawrence Wong said, “Compared to other OECD countries, Singapore devotes a larger share of our teachers’ time to activities that are crucial for students’ holistic development, such as CCAs, lesson preparation, and professional development.” And this approach has been well for Singaporean students.

Small is not always better. Big is not always bad.

When class size is too small, group dynamics become difficult. Individual students are more able to easily dominate the group and disrupt learning.

The optimum class size is not a fixed number. It varies according to the makeup of the class. It varies according to the learning needs of students. Larger classes have their advantages. They offer students a less isolated learning experience. They provide students with the opportunity to learn from each other. For older students, a larger class creates opportunities to sharpen their critical thinking skills, develop awareness, leadership skills, and social interaction with classmates from different backgrounds.

The focus on class size should therefore not be a fixed magic number.  It should be on the opportunities that it can create for students of various abilities to learn, to develop their skills, to collaborate, to interact, and grow their confidence, and to empower them to take charge of their learning beyond school education.

The mark of integrity is honesty in the usage of data, exercising strong moral principles in driving essential points. It is disingenuous of Jamus to refer to class size and teacher-student ratios without comparing the performances of the countries he compared.

To discredit the teachers despite having “tremendous respect for our teachers and efforts that they put in” is as good as apologising after delivering a slap to the victim’s face.

Uplift our teachers by providing feasible credible supplements to their work. Acknowledge that for education to succeed, all stakeholders (families, schools, teachers, students and society) have to work in tandem. Together, we can help make our education system better and better.

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