If you’re weighing up a bilingual school for your child, you’ve probably come across a mix of reassurances and concerns. Does learning in two languages slow things down academically? Will they fall behind in maths or science? And is it really worth it long-term?
These are fair questions, and the research has clear answers to all three. For over 30 years, Haut-Lac International Bilingual School has built and refined its bilingual education based on exactly that evidence. Here’s what we know.
Bilingual Education and Brain Development
One of the most well-documented findings in bilingualism research is its impact on executive function. In other words, the mental skills that help children focus, retain information and think flexibly.
Children who use two languages must constantly select the right one for the right moment. A direct reflection of this daily mental workout was seen by researchers from Bangor University, who studied Greek-English bilingual children in the north of England and found that bilingual pupils were notably faster on inhibition and working memory tasks than their monolingual classmates.¹ A broader 2023 analysis published in Developmental Review confirmed that same pattern.²
Research also links bilingualism to greater creativity, stronger metalinguistic awareness (an understanding of how language itself works), and improved working memory. These gains are not confined to language lessons, but transfer across subjects and stay with children throughout their education.
At Haut-Lac, our immersive model in Infant and Primary is designed to build this kind of cognitive flexibility from the very start. Students work two full days in English and two full days in French every week so both languages become tools for thinking and learning, not subjects studied in isolation.
Does Bilingual Education Affect Academic Results?
One of the most persistent myths about bilingual education is that it slows academic progress. Research consistently says otherwise.
A 2024 study by UCL’s Institute of Education analysed data from over 3,000 pupils in the UK National Pupil Database. It found that whilst multilingual learners can face some initial challenges at primary level, they catch up with their monolingual peers by secondary school and then go further.³
A large-scale RAND Corporation study following over 1,600 students in dual-language immersion programmes points to the same trajectory. Students outperformed their peers on reading tests by 13% at Grade 5 and by 22% at Grade 8, with no drop in maths or science.⁴
And in Canada, where French-English immersion has been practised for over 50 years, research consistently finds that students in bilingual programmes match or exceed their peers in core academic subjects, with advantages that grow stronger over time.⁵
All of these studies share one key finding: sustained exposure matters. The benefits compound the longer students remain in a bilingual programme. This is exactly what Haut-Lac’s model is designed to support from Infant and Primary all the way through to the Bilingual IB Diploma.
Many Haut-Lac Students Are Already Multilingual
In an international school like Haut-Lac, “bilingual” often undersells the picture. For many of our students, English or French is already a third language. Far from being a disadvantage, this is an asset.
Research shows that the language skills children develop in one language transfer to the next, so each additional language becomes easier to acquire⁶.
A strong home language helps too. Children who continue to develop their mother tongue tend to learn additional languages more effectively. Our approach does not aim to replace a child’s home language. It builds on it, expanding each student’s linguistic repertoire while strengthening their confidence in both French and English.
Why Starting Early Matters
The evidence is consistent: start young. Young children’s brains are particularly receptive to language acquisition, and early, consistent immersion produces more durable results than instruction that begins later. The UCL/Birkbeck study reinforces this directly with evidence suggesting children exposed to more than one language before the age of three show the greatest long-term academic advantages.³
Bilingual learning at Haut-Lac begins in Nursery and Kindergarten, so language becomes a normal part of how children engage with the world around them. Our teachers are predominantly native speakers of the language they teach in, which means students hear authentic, natural language use from day one.
Bilingual Education in Each School Section at Haut-Lac
| Stage | Approach |
| Infant & Primary | Full immersion across subjects with English and French on alternate days |
| Secondary (MYP 1-2) | All subjects taught in both languages, with the language of instruction alternating each semester |
| Secondary (MYP 3 onwards) | Students choose which subjects to study in each language |
| IB Diploma | Option to pursue the Bilingual or Advanced IB Diploma |
This flexibility reflects a key insight from the research: bilingual education works best when it adapts to the learner rather than applying one fixed model. What stays constant at Haut-Lac is the expectation that both languages remain active throughout a student’s education.
The Long-Term Picture: University and Careers
The advantages of bilingual education extend well beyond school as the demand for multilingual employees rises worldwide. An OECD report on language skills in the European labour market found that multilingual individuals are increasingly sought after across sectors including finance, international trade and professional services.⁷
The economic stakes are real at a national level too. Switzerland attributes an estimated 10% of its GDP to its multilingual heritage. Britain, by contrast, is estimated to lose the equivalent of 3.5% of its GDP every year due to relatively poor language skills across its workforce.⁸
Bilingual graduates are better placed to access international universities, navigate multicultural workplaces, and communicate across borders. These are skills that are increasingly difficult to replicate with technology alone.
At Haut-Lac, the Bilingual or Advanced Bilingual IB Diploma is the culmination of this journey. It is a rigorous, internationally recognised qualification that demonstrates academic fluency in two languages and is valued by universities worldwide. Our graduates go on to leading institutions across Europe, North America and further afield, and many credit their bilingual education as one of the most significant advantages they carried with them.
Read more about where Haut-Lac graduates go and explore our full bilingual programme.
Is Bilingual Education Right for Every Child?
Bilingual education is not one-size-fits-all, and Haut-Lac’s model is designed with that in mind. Students can join the bilingual programme without being bilingual on arrival. Our EAL and FLA specialists work alongside classroom teachers to develop individual language support plans, so no child falls behind whilst their skills develop.
For families uncertain about the bilingual route, we also offer an English-stream option with daily French lessons. Students can transition into the full bilingual programme once their confidence grows.
What the research makes clear is this: the earlier and more consistently children are immersed in two languages, the greater the long-term cognitive, academic and professional benefits. Three decades of student outcomes at Haut-Lac reflect that. So does the research.
Interested in how bilingualism works at Haut-Lac? Read our blog post entitled Bilingualism: what’s true and what’s not? or check out our bilingual education FAQ.
Renaud Milhoux
Head of Nursery, Infant & Primary
Haut-Lac International Bilingual School
About Haut-Lac:
Haut-Lac International Bilingual School is a leading IB World School on the shores of Lake Geneva, Switzerland. For over 30 years, it has offered a fully bilingual French-English education from Kindergarten through to the IB Diploma.
Footnotes:
- Paulay, A. et al. (2023). Bilingual children outperform monolingual children on executive function tasks far more often than chance: An updated quantitative analysis. Developmental Review. doi.org/10.1016/j.dr.2023.101090
- Papastergiou, A. et al. (2023). A study on the executive functioning skills of Greek–English bilingual children: a nearest neighbour approach. Bilingualism: Language and Cognition, 26(1), 78–94. Bangor University. doi.org/10.1017/S1366728922000402
- Moschovou, A. et al. (2024). The impact of multilingualism and socio-economic status on academic performance: evidence from the SCAMP and the national pupil databases. International Journal of Bilingual Education and Bilingualism. UCL Institute of Education / Birkbeck, University of London. ucl.ac.uk/ioe/news/2024/oct/multilingual-learners-reap-significant-academic-benefits
- Steele, J.L. et al. (2017). Effects of dual-language immersion programs on student achievement: Evidence from lottery data. American Educational Research Journal. RAND Research Brief: rand.org/pubs/research_briefs/RB9903.html
- Genesee, F. (2015). Bilingual education for young children: review of the effects and consequences. International Journal of Bilingual Education and Bilingualism. pmc.ncbi.nlm.nih.gov/articles/PMC6168086
- Thomas, W.P. & Collier, V.P. (2002). A National Study of School Effectiveness for Language Minority Students’ Long-Term Academic Achievement. CREDE/UC Santa Cruz.
- OECD (2023). The Demand for Language Skills in the European Labour Market. oecd.org
- Hogan-Brun, G., University of Bristol (cited in World Economic Forum, 2018). Why speaking more than one language can boost economic growth. weforum.org/stories/2018/02/speaking-more-languages-boost-economic-growth
