Basic rights and Equality

Language of instruction matters for learning foundational skills

4 min


Yew Chong Soh, Ximena V. Del Carpio and Liang Choon Wang

The advantages of multilingualism are undeniable. But should education systems use a language of instruction that is unfamiliar to children (and teachers) when teaching foundational skills? An increasing body of evidence says no. This column contributes to understanding why not.

Since gaining independence, many former colonies have faced the dilemma of whether to continue using the colonial language in their education system or to revert to their native language. Some countries have maintained the colonial language as the language of instruction in schools, while others have replaced the colonial language with their local language.

To some, teaching school students in their native language seems to be an obvious choice. Since children learn at school through spoken and written language, learning in the mother tongue, especially during the early years of formal education, may help them to improve their cognitive skills, and allow them to transfer their knowledge to learning in a second language later on.

Language of instruction may also have effects on teachers’ ability to teach. Poor outcomes for students may be exacerbated if their teachers have limited or sub-standard command of the language of instruction.

On the other hand, teaching in a non-native language may be more useful. Fluency in the dominant language used in the local economy, typically the colonial language, may bring better job market outcomes. This is especially true with the English language, where there may be employment advantages even in countries where English is not widely spoken.

Having a well-designed language policy can make a difference to learning in a multilinguistic environment. But how to best impart various languages to children, without sacrificing their ability to develop core skills, is a major concern for both families and policy-makers.

Unfortunately, this choice can be difficult to make in countries with dozens of different languages and dialects, or in contexts where students speak one language at home and another in the playground or classroom.

It is also a challenge for researchers to get clear estimates of the impact of language of instruction on children’s cognitive skills. For a start, countries that change their language of instruction in schools typically do so abruptly. They also tend to apply the change to all students at once, making it difficult to distinguish the effects of a switch in language of instruction from the effects of children learning in their first or second language.

In addition, data are not widely available since many of the language policy changes around the world occurred several decades ago. Standardized tests were not widely conducted at that time.

Finally, when the language of instruction is changed, both students and teachers are affected. Even if it were possible to study the impact of a policy change on test scores, it is difficult to differentiate the effects of the language change on children’s ability to learn and on the quality of teachers’ instruction.

In recent research, we focus on a language policy change in Malaysia. Variations in the way that the policy was applied to different cohorts of students speaking different native languages provide a unique setting in which to distinguish the effects of switching the language of instruction and the effects of using a non-native language (English) as the language of instruction.

We measure the impacts on the test performance of children who speak different native languages (Bahasa Malaysia, Chinese, or Tamil) with the help of several waves of data from the Trends in International Mathematics and Science Studies (TIMSS) and a research technique known as the synthetic control method to provide a reliable counterfactual – what would have happened in different circumstances.

Our results show that students performed worse in mathematics and science tests after the language of instruction in these subjects was switched from Bahasa Malaysia to English between their primary and secondary school years.

The impact of learning mathematics and science in English throughout primary and secondary education was even more negative. Boys fared worse than girls across the board.

The study suggests that children learning in their native languages develop their core skills better. But it is not able to quantify the extent to which changing the language of instruction negatively affected teachers’ ability to teach.

Our research and much of the evidence simply shows that when children are taught in their native language, they can more effectively acquire core skills that are important for the development of other skills.

Unfortunately, such evidence is often overlooked, to the detriment of children’s learning. It is estimated that 40% of school students worldwide are not taught core subjects in a language that they speak and understand regularly. As a result, many of them, especially among the most disadvantaged, are unable to learn critical skills that can help them in the longer term.

Given the importance of implementing the ‘right’ language policy, it is vital that teaching is done in the most effective language, and consistently, to prevent harming learning outcomes and to ensure that children have the best chance to learn foundational skills.

As change in educational systems is inevitable, we hope that studies like this one, and many others supporting the need to teach foundational skills in a native language, are not omitted from consideration by those designing and implementing language policy.


Yew Chong Soh
Consultant, World Bank Group
Ximena V. Del Carpio
Practice Manager, World Bank Group
Liang Choon Wang
Lecturer, Monash University