Pre-school pupils are still better readers aged 15
Children who have been in pre-school education are likely to be much better readers when they are aged 15, reveals a study of international test results.
The OECD has published an analysis of tests taken by pupils in developed countries - looking at the long-term impact of pre-school education.
This showed that 15-year-olds who had attended pre-school were on average a year ahead of those who had not.
This advantage was particularly strong for pupils in the UK.
The study from the Organisation for Economic Co-operation and Development, is based on international tests taken by pupils in industrialised countries, the Programme for International Student Assessment (Pisa).
The most recent results were published in December, based on tests taken in 2009 by 15-year-old pupils in 65 school systems.
This latest study looks at the links between achievement in these tests and pupils' first experiences of education.
It found that in almost all countries taking part in the tests, pupils who had attended pre-school, such as nursery or children's centres from the age of three, outperformed those who had not.
This gap remained after different social backgrounds had been taken into account.
But since pre-school education is more likely among better-off families, this can create an early social divide between pupils.
The research also suggests that disadvantaged and immigrant families can gain above-average benefits from early education.
There are considerable differences between countries in how much children are advantaged by pre-school education.
The UK is among the countries where there is the most marked advantage in having attended pre-school, along with countries such as Israel, France, Italy, Denmark and Switzerland.
At the other end of the scale, there are a group of countries in which there is relatively little connection between attending pre-school and later performance - including Estonia, Finland, Ireland and South Korea.
The study shows there are substantial differences in the numbers of pupils in pre-school education.
In France, Japan and Belgium it is described as near-universal, while in Canada, Ireland and Poland less than 50% of children attend pre-school.