DHAKA – It is almost universally agreed that more education is good for society. But it turns out that some popular educational policies achieve very little, while others that are often overlooked can make a huge difference.

Reducing class sizes would seem to be an obvious improvement; but by itself, smaller class size has not been shown to boost educational performance. Likewise, extending the school day seems an easy way to ensure that pupils learn more; but research finds that time spent in school matters considerably less than what happens there.

And new research for the Copenhagen Consensus Center, the think tank I direct, highlights the counter-intuitive fact that equipping classrooms with additional textbooks or computers is no educational silver bullet, either. As part of a project seeking the smartest policy choices for Bangladesh, Atonu Rabbani of the University of Dhaka shows that technology-aided teaching has a mixed record. Providing pupils with computers made some impact in India, but little in Colombia. In the United States, introducing computers has even been detrimental when not backed by parental supervision and teacher guidance.

This finding is supported by a recent OECD study, which revealed that over the last decade there has been no "appreciable improvement” in student achievement in the rich countries that invest most in technology for education.

Surprisingly, the same is true when it comes to basic, conventional schooling improvements like providing extra textbooks and building libraries. In assessing research relevant for policymakers in Bangladesh, Rabbani found only one study showing that additional textbooks definitely improved test scores – and only the top students benefited.

Fashionable projects such as providing laptops to pupils attract a lot of financial support, but it is not always money well spent. Peru, which has received a third of all laptops provided through the organization One Laptop per Child, hosted the first randomized controlled trial to test whether children with a computer did better than those without. The verdict? "There were no impacts on academic achievement or cognitive skills.” In fact, teachers reported that children who received laptops were significantly less likely to make an effort at school.

So how can policymakers do the most good? A seminal study from Jamaica suggests that early childhood interventions can make a world of difference.

The Jamaican study focused on children suffering from stunting, or chronic malnutrition, which affected 171 million children globally in 2010. Stunting starts before birth and is caused by poor maternal nutrition and food quality, along with frequent infections. Lifelong effects can include delayed cognitive development, lower productivity, and increased vulnerability to certain diseases.

In the mid-1980s, Jamaican social workers visited stunted children in their homes for one hour each week for two years, teaching their mothers how to play with their children to promote development. At the outset, these children lagged behind their peers in all development tests. But over the two years of home visits, the children’s development improved. And when researchers went back 20 years later, the results were amazing. The stunted children earned just as much as their peers. Stunted children who had not been part of the program earned 25% less.

In Bangladesh, six million children are stunted – four in ten children below the age of five years old, compared to the global average of around 25%.

Setting up early-childhood education centers in Bangladesh could transform lives, at a cost of around $300 per student. Based on the Jamaican study, income improvements would be worth around $10,000 over each child’s lifetime. In a country where per capita income is just over $1,000, this is significant. Each dollar spent would help disadvantaged children become $35 more productive.

Another educational approach that shows promise is "streaming,” whereby students are assigned to groups according to their educational levels. This can be controversial because of its perceived marginalization of low-achieving students. But there is increasing recognition that teachers can focus their efforts better when classes have a smaller gap between the lowest- and highest-performing kids.

In India and Kenya, streaming has lifted test scores. For Bangladesh, it is estimated that spending $100 dividing students (and potentially employing some extra teachers) would increase scores by nearly two standard deviations. Based on other studies, this would raise future annual earnings by as much as 8%. That’s a great return on investment: Each dollar spent would yield social benefits worth $12.

Whether for Bangladesh or elsewhere, the real lessons to be taken away from this research is that we need to look past trendy policies like adding technology to classrooms. The key to educational progress is to focus on interventions backed by credible scientific evidence.

Bjørn Lomborg, a visiting professor at the Copenhagen Business School, is Director of the Copenhagen Consensus Center

Copyright: Project syndicate