But rising income inequality explains, at best, half of the increase in the rich-poor academic achievement gap. It’s not just that the rich have more money than they used to, it’s that they are using it differently. This is where things get really interesting. High-income families are increasingly focusing their resources — their money, time and knowledge of what it takes to be successful in school — on their children’s cognitive development and educational success. They are doing this because educational success is much more important than it used to be, even for the rich.

Here’s a fact that may not surprise you: the children of the rich perform better in school, on average, than children from middle-class or poor families. Students growing up in richer families have better grades and higher scores, on average, than poorer students; they also have higher rates of participation in extracurricular activities and school leadership positions, higher graduation rates and higher rates of college enrollment and completion. Whether you think it deeply unjust, lamentable but inevitable, or obvious and unproblematic, this is hardly news. It is true in most societies and has been true in the United States for at least as long as we have thought to ask the question and had sufficient data to verify the answer.

What is news is that in the United States over the last few decades these differences in educational success between high- and lower-income students have grown substantially. We are still talking about this despite decades of clucking about the crisis in American education and wave after wave of school reform. Whatever we’ve been doing in our schools, it hasn’t reduced educational inequality between children from upper- and lower-income families. Part of knowing what we should do about this is understanding how and why these educational disparities are growing.

If not the usual suspects, what’s going on? It boils down to this: The academic gap is widening because rich students are increasingly entering kindergarten much better prepared to succeed in school than middle-class students. This difference in preparation persists through elementary and high school. As you may have heard, the incomes of the rich have grown faster over the last 30 years than the incomes of the middle class and the poor. Money helps families provide cognitively stimulating experiences for their young children because it provides more stable home environments, more time for parents to read to their children, access to higher-quality child care and preschool and — in places like New York City, where 4-year-old children take tests to determine entry into gifted and talented programs — access to preschool test preparation tutors or the time to serve as tutors themselves.

As inequality has increased,” she writes, “debate about the extent of mobility in American society has heightened. As income gaps have widened, the opportunity that children have to do better than their parents is increasingly important. . . . Whether they do so at a faster or slower rate than they did in the past is not a settled question. But since the rungs of the ladder are further apart than they used to be, the effects of family background on one’s ultimate economic success are larger and may persist for a longer period of time.”2

We need to start talking about this. Strangely, the rapid growth in the rich-poor educational gap provides a ray of hope: if the relationship between family income and educational success can change this rapidly, then it is not an immutable, inevitable pattern. What changed once can change again. Policy choices matter more than we have recently been taught to think. So how can we move toward a society in which educational success is not so strongly linked to family background? Maybe we should take a lesson from the rich and invest much more heavily as a society in our children’s educational opportunities from the day they are born. Investments in early-childhood education pay very high societal s. That means investing in developing high-quality child care and preschool that is available to poor and middle-class children. It also means recruiting and training a cadre of skilled preschool teachers and child care providers. These are not new ideas, but we have to stop talking about how expensive and difficult they are to implement and just get on with it.

we have evidence that collectively society doesn’t advance with organized education, rather the reverse: the level of (formal) education in a country is the result of wealth.

The achievement gap between children from high income and low income families is roughly 30-40% larger among children born in 2001 than among those born 25 years ago. The class gap among students entering kindergarten was two to three times higher than the racial gap.

Education is not a way to escape poverty, it is a way of fighting it. Economic inequality is growing and the kind of education system a country has will have a major impact on the capacity to respond to this.

Before we can figure out what’s happening here, let’s dispel a few myths. The income gap in is not growing because the test scores of poor students are dropping or because our schools are in decline. [...] The widening income disparity in academic achievement is not a result of widening racial gaps in achievement, either. The achievement gaps between blacks and whites, and Hispanic and non-Hispanic whites have been narrowing slowly over the last two decades, trends that actually keep the yawning gap between higher- and lower-income students from getting even wider. If we look at the test scores of white students only, we find the same growing gap between high- and low-income children as we see in the population as a whole.

those at the very top of the class — are going to face a burden that they would not face in a less competitive atmosphere. Citizens of happy countries have higher suicide rates than citizens of unhappy countries, because they look at the smiling faces around them and the contrast is too great. Students at “great” schools look at the brilliant students around them, and how do you think they feel? The phenomenon of relative deprivation applied to education is called — appropriately enough — the “Big Fish–Little Pond Effect.” The more elite an educational institution is, the worse students feel about their own academic abilities. Students who would be at the top of their class at a good school can easily fall to the bottom of a really good school. Students who would feel that they have mastered a subject at a good school can have the feeling that they are falling farther and farther behind in a really good school. And that feeling — as subjective and ridiculous and irrational

So let me repeat: The combined trends of increased inequality and decreasing mobility pose a fundamental threat to the American Dream, our way of life, and what we stand for around the globe. And it is not simply a moral claim that I’m making here. There are practical consequences to rising inequality and reduced mobility. For one thing, these trends are bad for our economy. One study finds that growth is more fragile and recessions are more frequent in countries with greater inequality. And that makes sense. When families have less to spend, that means businesses have fewer customers, and households rack up greater mortgage and credit card debt; meanwhile, concentrated wealth at the top is less likely to result in the kind of broadly based consumer spending that drives our economy, and together with lax regulation, may contribute to risky speculative bubbles.

A world in which one percent of humanity controls as much wealth as the other 99 percent will never be stable. I understand that the gaps between rich and poor are not new, but just as the child in a slum today can see the skyscraper nearby, technology now allows any person with a smartphone to see how the most privileged among us live and the contrast between their own lives and others. Expectations rise, then, faster than governments can deliver, and a pervasive sense of injustice undermine people’s faith in the system. [...] economies are more successful when we close the gap between rich and poor, and growth is broadly based. And that means respecting the rights of workers so they can organize into independent unions and earn a living wage. It means investing in our people -- their skills, their education, their capacity to take an idea and turn it into a business. It means strengthening the safety net that protects our people from hardship and allows them to take more risks -- to look for a new job, or start a new venture.

Inequality in education starts early, and it starts at home. A study by the University of Kansas found that by the time she is three years old, a child who grows up in a home on welfare will hear thirty million fewer words than a child who grows up in the home of a professional family.* Words like “portfolio” and “equestrian.” We know that kids who have had a quality early childhood education are less likely to be placed in special education, less likely to be left back a grade,