SOBRE ESTE EPISÓDIO
More households in low-income countries own a mobile phone than have electricity or clean water. So why is education one of the last places it has been put to work?
Jenny Aker (Cornell) and Noam Angrist (Oxford) are the academic leads on a J-PAL Policy Insight that reviews 30 studies of mobile phone programmes in education. They tell Tim Phillips that the cheapest option, blasting out SMS messages, is usually the one that fails. But put a real person on the other end of the line, and that's an effective and inexpensive way to improve education. The phone is a platform, Angrist points out, not a pedagogy.
The research behind this episode:
Abdul Latif Jameel Poverty Action Lab (J-PAL). 2026. "Leveraging Mobile Phones for Learning." J-PAL Policy Insight. Academic leads Jenny Aker and Noam Angrist; insight authors Jessica Williams and Demitria Wack.
To cite this episode:
Phillips, Tim, Jenny Aker, and Noam Angrist. 2026. "Using mobile phones to support teachers, parents, and students." VoxDev Talks (podcast).
About the guests
Jenny Aker is the Daniel G. Sisler Professor of Development Economics at Cornell University. She is also a non-resident fellow at the Center for Global Development and co-chair of the Digital Identification and Finance Initiative at J-PAL Africa. Her research spans mobile technology and agricultural markets, adult literacy and numeracy, financial inclusion, and the design of cash transfers and social protection in Africa.
Noam Angrist is Academic Director of the What Works Hub for Global Education and Senior Research Fellow at the University of Oxford, and co-founder of Youth Impact, one of the largest NGOs scaling health and education programmes backed by randomised trial evidence. His research spans distance education, the measurement of implementation, and how programmes that work in a trial can be made to work at national scale.
Research and concepts cited in this episode
One Laptop per Child. The plan to put a cheap laptop in the hands of every child in the developing world, launched in 2005 and abandoned as evidence of its effect on learning failed to appear. Angrist raises it as the cautionary tale for anyone introducing a device: the schools could not absorb it, the software was an afterthought, and nobody planned for charging or breakage. Phones avoid that problem because they are already there, so the marginal cost of adding good pedagogy is low. A long-term follow up from rural Peru found no positive effect on educational outcomes.
Mobile coverage. GSMA. 2025. "The State of Mobile Internet Connectivity 2025." Around 95% of the world's population now lives within range of a broadband network. In sub-Saharan Africa coverage is about 80% and adoption about 60%, and what people mostly hold is a simple handset rather than a smartphone.
Phone tutoring in emergencies. Angrist, Noam, Micheal Ainomugisha, Sai Pramod Bathena, Peter Bergman, Colin Crossley, Claire Cullen, Thato Letsomo, Moitshepi Matsheng, Rene Marlon Panti, Shwetlena Sabarwal, and Tim Sullivan. 2023. "Building Resilient Education Systems: Evidence from Large-Scale Randomized Trials in Five Countries." NBER Working Paper 31208, revised 2025. Weekly maths texts combined with live tutoring calls raised test scores by 0.30 to 0.35 standard deviations at an average cost of US$11 per child. SMS on its own moved the needle only where access to learning was already very low.
Scaling up without the drop. The first Botswana phone tutoring trial produced an effect of about 0.12 standard deviations; by the fifth replication, in Uganda, Angrist says the effect was over 0.8, and implementation fidelity data improved in step with the order of the studies. He sets this against the voltage drop described by John List in The Voltage Effect (2022), the tendency of programmes to lose their punch as they scale. Common, Angrist argues, but not inevitable.
A/B testing the tutoring call. Angrist, Noam, Claire Cullen, and Janica Magat. 2025. "Cheaper (and More Effective) by the Dozen: Evidence from 12 Randomised A/B Tests Optimising Tutoring for Scale." What Works Hub for Global Education Working Paper 2025/001. Roughly half the cost of a tutoring programme goes on scheduling rather than teaching. One call of 40 minutes every fortnight, instead of 20 minutes every week, delivered the same dosage for less. Handing the call to a parent partway through doubled to tripled the effect; motivational nudges to parents did nothing.
Monitoring teachers by phone. Aker, Jenny C., and Christopher Ksoll. 2019. "Call Me Educated: Evidence from a Mobile Phone Experiment in Niger." Economics of Education Review 72: 239 to 257. Weekly calls to the teacher, the village chief and two students raised maths and reading scores. The counter-example comes from Côte d'Ivoire, where nudging parents and teachers at the same time left the most motivated teachers turning up less; too much scrutiny, the authors suggest, corroded the motivation the programme depended on.
Platform and pedagogy. Angrist's phrase for the distinction the review keeps returning to. The phone carries an intervention; it is not the intervention. Targeted instruction and early childhood stimulation both travel down the line, but somebody still has to decide how often to call, who picks up, and what happens on the call. The same traffic makes the phone a good instrument for research, since the data is traceable and the units of randomisation are well powered.
Education Cannot Wait. The United Nations fund for education in emergencies and protracted crises. Its 2022 global estimate put 222 million crisis-affected children and adolescents in need of urgent education support, up from about 75 million in 2016. Angrist uses the same figure in the five-country paper, and cites it here to make the point that the humanitarian structures for education in emergencies exist while the evidence base underneath them barely does.
More VoxDev Talks episodes
How AI can put 20 years of development evidence to work. Iqbal Dhaliwal on why One Laptop per Child failed, and what that failure should teach anyone now betting on AI in development.
Why we need to invest in foundational learning. Benjamin Piper on the gap between getting children into school and getting them to read, which is the gap most of these phone programmes are trying to close.
Related reading on VoxDev.org
How simple technologies can improve learning: Evidence from Niger, in which Jenny Aker and Christopher Ksoll show that a weekly call to teachers and students almost doubled the effect of an adult education programme.
Educating children in emergencies: Global evidence from five randomised trials, the five-country evidence on cheap phone tutoring that runs through much of this conversation.
How AI tutors improved learning in Nigeria, on a six-week after-school programme in Edo State that produced large gains in English, and on the guardrails that made it work.
