Research published by the Sutton Trust shows that for schools in the UK, the achievement gap in maths, science and reading between the top-performing pupils from low and high socio-economic backgrounds is around two years and eight months.
Global Gaps by Dr John Jerrim of the UCL Institute of Education analyses the 2015 test scores from the Organisation for Economic Co-operation and Development (OECD) PISA tests to assess how well the top 10% of pupils in the UK’s schools are doing. In England, the highest-achieving pupils score above the median score for OECD countries in maths, science and reading. However, in Scotland, Northern Ireland and Wales, high-achieving pupils perform, on average, below the OECD median scores.
For girls in England, the achievement gap in science and reading is even greater. High-achieving girls from low socio-economic backgrounds are around three years behind their more advantaged, high-achieving peers. This is around eight months greater than the equivalent gap for boys for science, and nine months greater for reading. There is no significant gender difference in maths, with an achievement gap of around two years and nine months for both girls and boys.
Source: Global Gaps: Comparing socio-economic gaps in the performance of highly able UK pupils internationally (February 2017), The Sutton Trust