A recent study challenges the common belief that smaller class sizes improve student outcomes. Analyzing data from over 2,700 students in China and Japan, researchers found that reducing classroom sizes does not lead to better grades or higher resilience — at least among low-income secondary-level students. Surprisingly, smaller classes might even hinder students’ chances of achieving better results in some cases.

Instead, what the researchers found improved student outcomes was the quality of the teachers. That is teachers with high discipline standards, expertise, and effective learning strategies.

The study makes a strong case that policymakers ought to think twice before considering decreasing class sizes. The authors argue that resources are better spent on nurturing higher-quality teachers rather than spreading mediocre educators thin across small classrooms.

“This study supports the view that the quality of teachers, rather than the quantity, is the primary guarantee of students’ resilience,” says lead author Professor Tao Jiang, of Taizhou University.

“Quality teachers who effectively used teaching methods and managed classroom discipline increased the odds that individuals became resilient students.”

“On the other hand, emphasizing the reduction of class sizes in schools may not benefit resilience. Smaller classes either had no relevance to resilience or were disadvantageous for resilience.”

Good teachers over classroom size

The study looked into various factors affecting the resilience of 1,594 disadvantaged science students in Japan and 1,114 in the Macau region of China. In this context, academic resilience refers to the capacity of students to confront adversity (meeting homework deadlines, proper scheduling of study time, and so on) and thrive academically by earning good grades despite these obstacles. Learning scholars claim that academic resilience is not fixed but is rather a trainable quality that improves with practice and repeated success, with small wins stacking to improve the student’s overall resilience in the classroom.

All the participants were part of the Programme of International Student Assessment (PISA), an international questionnaire-based survey. PISA measures a pupil’s ability to use their reading, mathematics, and science knowledge. It offers a benchmark to evaluate learning quality across different countries.

The findings revealed that about a third of the students demonstrated high resilience, a quarter showed low resilience, and the remainder fell into the medium category. Those with high resilience had a more positive attitude towards school, science, and their future career prospects. They spent more time studying science but also reported feeling anxious about exams.

Contrary to expectations, smaller class sizes did not consistently contribute to better resilience. In some cases, they even had a negative effect. For instance, in Japan, reducing class size was detrimental, whereas a slight increase in class size significantly improved disadvantaged students’ chances of achieving better grades. The researchers didn’t suggest why this was the case — it is just an observation for the time being.

Beyond classroom numbers

Interestingly, the study found that in Japan, the most effective approach for boosting resilience was inquiry-based learning, whereas in Macau, direct instruction from teachers was more impactful. Inquiry-based learning encourages students to explore and discover answers through questions and experimentation, while direct instruction involves a structured approach where teachers explicitly teach specific skills or knowledge.

The influence of class size varied, with smaller classes not affecting resilience in Macau and negatively affecting it in Japan. However, a slight increase in class size in Japan was associated with a 1.2-fold increase in the likelihood of disadvantaged students achieving higher grades.

Additionally, the study found that classroom and school misbehavior negatively affects student resilience. Classrooms where teachers enforced rules, maintained discipline, and tailored lessons to meet student’s needs tended to fare the best.

The study sends a clear message: quality teaching matters more than class size in enhancing the resilience and academic performance of disadvantaged students. However, this isn’t the last word on the matter.

Still more to learn

The study focused on students in Japan and China and mainly on science classes with pupils from low-income backgrounds. Previous studies have found smaller classes lead to greater classroom engagement and higher attendance. In some research, the impact of small classes is more modest.

“Most studies find at least some evidence of positive effects of smaller classes, but the size of these benefits is inconsistent,” wrote Urban Institute researcher Matt Chingos.

The new finding shifts the narrative from quantitative adjustments in class size to qualitative improvements in teaching. It calls for strategic investments in teacher development and training as the most effective way to support student success, particularly among those from low-income backgrounds. But a combination of the two — training better teachers and lowering classroom sizes — shouldn’t be discounted either, although this is surely challenging to apply considering the insufficient resources dedicated to primary education across the world.

The findings appeared in the International Journal of Science Education.