In the most recent survey by the Organisation for Economic Cooperation and Development (OECD) of adult skills, the US and the UK were languishing at the bottom of the international league tables. One finding was of particular concern: that the skills of younger workers showed little or no improvement on those of their older counterparts. As the OECD argues: “Young people in these countries are entering a much more demanding labour market, yet they are not much better prepared than those who are retiring.”

These findings were greeted with much wailing and gnashing of teeth by politicians on both sides of the pond. Arne Duncan, the US secretary of state for education, said that the findings “show our education system hasn’t done enough to help Americans compete”. In the UK, skills minister Matthew Hancock was even more forthright. “This shocking report shows that England has some of the least literate and numerate young adults in the developed world,” he said.

But are the politicians right to blame the low skills base of young adults on their countries’ education systems? Rational analysis would suggest not. As the UK government’s recent report on social mobility and child poverty states, schools account for only about 20 per cent of the variation in attainment between children.

This is not to deny that they play an important role in raising educational standards or that they should be strong engines of social mobility. Schools can improve the academic attainment of disadvantaged students by positive policies and actions. Research by the OECD has shown that educational systems that do well by their poorest students place a strong emphasis on collaboration between schools, so that effective practice is shared and developed.

Teacher quality is another important factor. The poorest children need the most effective teachers working in a professional environment where teaching is a high-status profession with ambitious standards and high performance expectations. The OECD also poses a key challenge to much current school practice and political rhetoric when it concludes that segregation by ability disproportionately disadvantages the poorest children, reinforcing low expectations and denying those students access to a broad and balanced curriculum.

However, with 80 per cent of a child’s educational performance unaffected by the school they attend or the policies it adopts, it is time for politicians look further afield for the factors that inhibit social mobility.

Impoverished vision

In widening their gaze, politicians should be much more concerned about, and determined to end, child poverty. Figures for the US and the UK are shocking: nearly half (48 per cent) of American children live in poverty, while 2.6 million children in the UK live in absolute income poverty.

There can be no doubt that child poverty is the major influence on educational attainment. Developmental gaps between children born in better-off and worse-off families are established by the age of 3, driven in large part by their home circumstances. Inequality and disadvantage start at birth and quickly become entrenched. Poor children are half as likely to be breastfed. Their mothers are three times more likely to suffer from depression. US researchers have demonstrated that children from high-income families will hear 30 million more words within the first four years of life than poor ones.

Language is central to educational attainment: children need to use it effectively to express their thoughts, develop their ideas and understand their teachers. But poor children do not suffer only from language deprivation: all aspects of their life are affected. One American research study used survey data to show that, before the age of 6, children from affluent families spent 1,300 more hours than their low-income counterparts in places other than their homes, their day-care centres or schools. By the time high-income children start school, they have spent about 400 hours more than poor children on literacy activities.

Schools simply cannot compensate for the serious and lasting effects of child poverty. In England, the gap in attainment between children eligible for free school meals and the rest is 19 per cent at age 5, 17 per cent at 11 and 26 per cent at 16. In the US, researchers from the University of Michigan have found that the imbalance between rich and poor children in college completion - the single most important predictor of success in the workforce - has grown by about 50 per cent since the late 1980s. Inequality blights children’s lives and their futures.

If politicians are to do more than preach about social mobility or wring their hands about the educational attainment of poor children, they need to address the root cause of educational inequality: poverty. It should be no surprise to anyone that children find it more difficult to learn if they are living in poor housing and arrive at school hungry and inadequately clothed. It is no surprise to anyone that stressed parents, plagued by low incomes, job insecurity and all the instability that brings to their relationships, should have less time and fewer resources (both human and financial) to invest in their children.

School teachers and support staff work every day to alleviate the burden that poverty places on the life chances of poor children. They do not need lectures on social mobility from politicians whose policies increase child poverty and blight poor children’s futures.

Mary Bousted is general secretary of the UK’s Association of Teachers and Lecturers.