A weekly 20-minute phone tutorial raised math scores in all five countries tested
Five randomized trials run during pandemic school closures found that a weekly 20-minute phone tutorial produced basic math gains in every country tested, while text messages alone gave mixed results across the same settings.
The Scientist · Science desk
What happened
- A Nature paper reports five randomized trials of remote tutoring during school closures, run in India, Kenya, Nepal, the Philippines and Uganda.
- More than 16,000 households with primary school students took part between December 2020 and July 2022.
- Students were randomly assigned to no remote tutoring, to weekly text messages with math problems and practice reminders, or to those texts plus a weekly 20-minute one-to-one phone tutorial.
- In the phone group the number of students correctly solving division problems rose 92%, and performance on fractions improved by 6.4 percentage points.
- phys.org places the combined program, at $11 per child, among the top 10 most cost-effective education interventions of 150 evaluated worldwide.
Why it matters
- What's now possible capability The effect held whether government teachers or NGO instructors made the calls, so a ministry can mount this on staff it already employs and a list of phone numbers, with no platform to procure or connect.
- What it limits constraint An internet-delivered closure plan can reach under 15% of households in low-income countries, against more than 70% reachable by phone. That gap caps how much of a population any app-based continuity plan can serve.
- What doesn't add up contradiction The two write-ups price the same program differently, at 3.6 years of schooling per $100 and at approximately 4, so a budget built on the higher number claims about a tenth more value than the detailed account supports.
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Each call opened with a short assessment. The instructor used it to work out what the child could already do, then built that week's lesson on it instead of following the grade-level curriculum [3]. Twenty minutes a week for eight to twelve weeks comes to between 2 hours 40 minutes and 4 hours of one-to-one instruction per child over the whole program [18]. Divide the per-child cost by that time and the combined package ran at roughly $2.75 to $4.15 per hour of live tutoring, text messages included [19].
Cost-effectiveness here is a conversion. The metric turns test-score gains into an equivalent quantity of schooling, and on the lower of the two published accountings, $11 per child works out to about 0.4 years, close to five months [20]. No child in these trials sat through five months of instruction.
phys.org writes that students learned roughly three times more when they received phone calls tailored to their learning level [11], and further down gives the comparison: the average gain of 0.321 standard deviations was three times larger than the median education intervention evaluated globally [4] [5]. The reference point for that number, then, is the global median. On the text messages, the authors wrote in Nature: "Whereas text messages have mixed results, tutorials conducted via phone call show effectiveness across diverse settings" [7]. Neither source reports how much the calls added on top of the texts, and the SMS-only arm was not run in India at all [22].
The effect size also does not tell you how these children compared with children sitting in classrooms. Schooling was disrupted by COVID-19 in all five settings, and several of the study countries had some of the longest school closures in the world [12]. The gain is measured against children who received nothing remote while school was unavailable. That is the comparison an emergency plan actually faces, and the only one these trials could run.
Outcomes were basic math, tested at endline with the Annual Status of Education Report tool [16]. Neither source reports a reading result, and neither reports a follow-up test after the tutoring stopped. Education Cannot Wait, the UN fund for education in emergencies, estimates that 222 million children experience regular schooling disruptions [10]. Uganda and the Philippines saw the biggest improvements [17].
What to watch
- A follow-up test months after the calls stop, which would show whether the basic math gains hold.
- A costed national rollout by one of the study governments, with teachers carrying full class loads, to test the $11 per child outside a trial.
- A reading outcome from the same design; these five trials report basic math only.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence78
- Adoption40
- Hype gap+10
- Incentives55
- Confidence72
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
A Nature paper presents results from five randomized trials in India, Kenya, Nepal, the Philippines and Uganda evaluating the provision of education in emergency settings.
- [2]
Between December 2020 and July 2022, more than 16,000 households with primary school students from the five countries participated in the remote-learning experiment.
- [3]
Each week, instructors used a short assessment during the call to determine what the child could do, then designed the math lesson around those specific needs instead of simply following the grade-level curriculum.
- [4]
On average, students in the phone tutoring program gained 0.321 standard deviations in learning.
- [5]
The average gain meant that students' gains were three times larger than those of the median education intervention evaluated globally.
- [6]
The combined phone-call and SMS program is among the top 10 most cost-effective education interventions ever evaluated, out of 150 studies worldwide.
- [7]
"Whereas text messages have mixed results, tutorials conducted via phone call show effectiveness across diverse settings."
- [8]
Results show large effects when delivered by government teachers or NGO instructors.
- [9]
Fewer than 15% of households have access to the internet in low-income countries, while more than 70% have access to mobile phones.
- [10]
Education Cannot Wait, the United Nations' Global Fund for education in emergencies, estimates that 222 million children experience regular schooling disruptions and are in active need of education in emergencies programmes.
- [11]
Students learned roughly three times more when they received phone calls tailored to their learning level.
- [12]
In all settings, schooling was disrupted owing to the COVID-19 pandemic, and several of the countries in the study experienced some of the longest school closures in the world.
- [13]
Adding a weekly, one-on-one, 20-minute phone-call tutorial to text messages led to significant gains in basic math skills across all five countries.
- [14]
The combined phone-call and SMS program led to a 92% jump in the number of students who could correctly solve division problems, and performance on fractions increased by 6.4 percentage points.
- [15]
The combined phone-call and SMS tutorial program cost $11 per child.
- [16]
At the end of the trial, researchers tested progress using the standard Annual Status of Education Report tool.
- [17]
Uganda and the Philippines saw the biggest improvements.
- [18]
Eight to twelve weekly sessions of 20 minutes gives 160 to 240 minutes of one-to-one instruction per child, or 2 hours 40 minutes to 4 hours in total.
- [19]
At $11 per child for the combined program, the cost per hour of live tutoring is about $2.75 to $4.15.
- [20]
At 3.6 years of high-quality schooling per $100, the $11 spent per child equates to about 0.40 years, or roughly 4.8 months.
- [21]
Students in the control group received no remote tutoring during the trial period; the SMS-only group received weekly text messages containing basic math problems and practice reminders; the phone call and SMS group received the weekly text messages plus a 20-minute one-on-one phone tutoring session each week.
- [22]
The SMS-only group was not tested in India.
- [23]
The phone call and SMS group received a 20-minute, one-on-one phone tutoring session each week for 8 to 12 weeks.
- [24]
phys.org reports that for every $100 spent, the program generated 3.6 years of high-quality schooling.
- [25]
The Nature abstract states that the effects deliver approximately 4 years of high-quality instruction per US$100 spent.
- [26]
The Nature abstract's approximately 4 years per US$100 is about 11% higher than the 3.6 years per $100 reported by phys.org.
Sources
2 independent publishers whose own reporting we read for this story.
- nature.comMobile education builds resilience during shocks in five countries
1 article · September 8, 2026
- phys.orgLow-cost phone lessons keep children learning during emergency school closures across five countries
1 article · September 11, 2026
Topics and entities
Topics
- Mobile phone learning
- Education in emergencies
- Cost-effectiveness of social programs
- Randomized controlled trials