Randomized Trial of Two-Year Pre-primary Education Provides Reliable Evidence on Reform Effects
A large-scale randomized field experiment on two-year pre-primary education has produced reliable evidence on the effects of extending compulsory pre-primary education by one year.
The trial was carried out between 2021 and 2024 in 148 municipalities across Finland. A total of 37,357 children participated and were assigned to the trial and control groups by random draw.
Children in the trial group were invited to start compulsory and free pre-primary education at age five and attended it for two years. The control group continued in the current system. Because assignment was randomized, the groups were comparable in terms of background characteristics, which allows differences in outcomes to be interpreted as causal effects of the reform rather than as consequences of family choices or municipal practices.
The trial increased participation in early childhood education and care or pre-primary education among five-year-olds by 3.5 percentage points. The increase was explained by the free and compulsory nature of pre-primary education and by the transportation benefit granted to families. Parents, carers and teachers mainly experienced the trial positively. The amount and nature of play were similar in two-year pre-primary education and in regular early childhood education and care for five-year-olds.
On average, children’s socio-emotional skills and academic skills developed at the same rate in two-year pre-primary education as in the current combination of early childhood education and care at age five and one year of pre-primary education at age six. The trial did not reduce differences between children in skills assessed at the beginning of primary education, and the effects did not vary by family background.
Compared with home care, two-year pre-primary education improved children’s skills at the midpoint of the trial. However, these differences were no longer clearly visible at the beginning of primary education. Because the number of children transitioning from home care to pre-primary education was small, the results remain uncertain.
The total cost of implementing the trial was approximately EUR 22.2 million. If two-year pre-primary education were introduced nationwide and increased participation among five-year-olds by five percentage points, annual service provision costs are estimated to increase by approximately EUR 20–30 million, in addition to foregone municipal client fee revenues.
Implementing the reform as a large-scale randomized field experiment can be considered socially significant. It provides reliable empirical evidence on a major legislative reform before decisions are made about nationwide implementation. The trial strengthens the evidence base for education policy and reduces the risk of costly or ineffective reforms.
The evaluation of the two-year pre-primary education trial was conducted by a large multidisciplinary research team, which made it possible to examine the effects of the experiment from the perspectives of childhood development and learning as well as education policy. The project was led by Professor Matti Sarvimäki from the Aalto University Faculty of Economics. He is also a Chief Researcher at the VATT Institute for Economic Research. The research team also included Senior Researcher Ramin Izadi from VATT, as well as researchers in education, early childhood education, psychology, economics, and learning analytics from the University of Helsinki, Aalto University, the University of Jyväskylä, and the University of Turku.
The four-year research project was commissioned by Finland’s Ministry of Education and Culture. The randomized field experiment was made possible by a temporary Act on a Two-Year Pre-primary Education Trial adopted by the Finnish Parliament in December 2020. The research consortium published its final report in January 2026.
Final report:
Matti Sarvimäki, Anna Holvio, Julia Kuusiholma-Linnamäki, Mimmu Sulkanen, Maarit Alasuutari, Kaisa Harju, Oskari Harjunen, Ramin Izadi, Mirjam Kalland, Mikko-Jussi Laakso, Marja-Kristiina Lerkkanen, Heli Muhonen, Ville Ruutiainen, Pekka Räsänen, Anne-Elina Salo, Saara Salo, Lotta Saranko, Tuomas Suorsa, Katja Upadyaya ja Hilla Villanen (2026). Kaksivuotisen esiopetuksen kokeilu. Loppuraportti. Opetus- ja kulttuuriministeriön julkaisuja 2026:2.
Matti Sarvimäki
Ramin Izadi
Education
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