When it comes to education interventions in developing countries, we have an enormous wealth of research studying the effects of these interventions. The only problem is there hasn’t been a proper comparison of these programs that might show which interventions work best.

In a new report from the World Bank Group, researchers attempted to solve this problem by comparing more than 150 interventions in developing countries. From this, one clear trend emerged: Investing in teachers is strikingly cost-effective. 

Efforts to improve education in developing countries often focus on building schools, buying school uniforms or textbooks, or paying scholarships. But what the researchers found was that these popular interventions do not compare favorably to the ones that focus on teaching, which tells us that if we want to improve schools, the most cost-effective approach is to help teachers get professional training.

Why is investing in teachers so effective? The simplified answer is that if teachers don’t know how to teach, then students won’t learn. More specifically, the World Bank report cites a paper about one curriculum development intervention in Kenya called the Tusome national literacy program, which introduced national expectations for student performance, official classroom visits, and feedback to teachers. While that may sound basic, the fact of the matter is that this program set new expectations that didn’t exist before as there was no one checking whether teachers showed up or did their jobs.

The Tusome national literacy program was able to improve education simply by making teachers aware that they are in a professional role where they are expected to get results. When compared to more expensive interventions such as buying new textbooks, the Tusome literacy program and other teacher-focused interventions are far more effective.

Comparing education interventions is a complicated matter, especially because there is little to no uniformity when it comes to quantifying performance results in different countries. Despite this, the researchers say that there is little doubt that investing in teachers can help kids in developing countries get the best results.