Language of instruction matters for learning foundational skills


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A well-designed language policy can make a difference to learning in a multilinguistic environment. Photo: Shutterstock
A well-designed language policy can make a difference to learning in a multilinguistic environment. Photo: Shutterstock

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. And this piece contributes to understanding why not.

Since gaining independence, many former colonies have faced the dilemma of whether to continue using the colonial language in the education system or revert to their native language. Some countries maintained the colonial language as the language of instruction in schools while others replaced the colonial language with their local language. To some, teaching students in their native language seems like an obvious choice. But to others, teaching in a non-native colonial or mainstream or foreign language seems more useful. Unfortunately, this choice can be difficult to make in countries with dozens of different languages and dialects spoken, or in contexts where students speak one language at home and another language in the playground. 

Having a well-designed language policy can make a difference to student learning in a multilinguistic environment. But how to best impart various languages on children, without sacrificing their ability to develop core skills, is a major concern for many policymakers and families. Our paper delves into this question by focusing on a language policy change in Malaysia, where there were various quirks in the policy change in the way it was applied to different cohorts of students speaking different native languages. These elements provide us with a unique setting to differentiate between the effect of switching the language of instruction, and the effect of using a non-native, foreign 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 the synthetic control method to provide a reliable counterfactual.

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, a non-native language, throughout primary and secondary school years was even more negative. Boys fared worse than girls, across the board. The results suggest that children learning in their native languages develop their core skills better. Although the paper is unable to quantify the extent to which changing the language of instruction negatively affected a teacher’s ability to teach, findings from other studies indicate that the effect of changing the language of instruction on a teacher’s ability to teach is also likely to be adverse and exacerbated if the teacher has limited or substandard command of the new language of instruction.

Impact of the change in language policy on student’s mathematics (left) and science (right) test scores

Test scores
Note: The red vertical line indicates the eighth graders in 2007; the older cohort, affected by the change. The blue vertical line indicates the eighth graders in 2011; the younger cohort affected by the change. Average mathematics test scores displayed on the left-hand side panel and average science test scores displayed on the right-hand side panel.

The findings are consistent with the main messages from a recent World Bank report. Our paper, like the report, recognize that employing the native language as the language of instruction in a school has clear advantages but it is not without costs. Learning in the native language, especially during the first years of formal schooling, help children improve their cognitive skills in numeracy and problem-solving. Likewise, teachers may also teach more effectively in their native language. Worth noting that learning the colonial language (English in this case) may be economically valuable, as many jobs in the local economy and abroad require those language skills. However, mastering core skills such as numeracy and problem solving will not only likely yield a higher premium in the labor market but also help students have a more solid foundation for absorbing additional learning, including a second language.  

Our paper does not argue that children should not learn a second language. The paper 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, including that of learning a second language. Unfortunately, this evidence is sometimes overlooked, to the detriment of children’s learning.  In fact, it is estimated that 40 percent of the students worldwide are not taught core subjects in a language they speak and understand regularly.  As a result, many of these children, 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 important for teaching to be imparted in the most effective language, and consistently, to prevent harming learning outcomes and to ensure children have the best chance to learn foundational skills. In Malaysia, learning outcomes in critical subjects were harmed with the language switch. But given that 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. 



Ximena Del Carpio

Practice Manager, World Bank

Choon Wang

Lecturer, Monash University

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