- Children’s early numeracy skills are essential for educational and professional success, but many children in low- or middle-income countries fail to develop them
- Policymakers have tried to address this learning crisis by either improving caregivers’ or teachers’ ability to teach numeracy, but there is little evidence as to whether these approaches substitute for each other or complement each other
- An IDB study shows that both approaches significantly improve math learning, but combining them leads to no significant gains and would waste resources, an important finding for resource-strapped school systems
When a child struggles with early math, where should scarce resources go—into helping parents support learning at home, or into training teachers to teach better in the classroom? A new study from Colombia offers a surprising answer: doing both at once may be a waste of money.
Early numeracy skills strongly predict later academic success and even adult earnings. Yet in many low- and middle-income countries, children fall dramatically behind. In Colombia, only about 17% of students reached minimum math proficiency by the end of primary school in 2019.
A randomized controlled trial in the city of Manizales followed children from kindergarten into second grade to find out whether supporting parents or supporting teachers resulted in improved math learning. Each child was randomly assigned to one of four groups: a parental engagement program, a teacher training program, both, or neither.
Two Roads to the Same Destination
The first intervention reached parents the summer before first grade. Families got a workbook of playful activities built around household items—sorting bottle caps to count, setting the table to learn one-to-one correspondence—plus three text messages a week: a fact about child development, a practical tip, and an encouraging note.
The second intervention trained teachers over the first two grades of elementary school, through six workshops, weekly in-class coaching, and online support. First-grade teachers were trained in the first year and second-grade teachers the next, so children in these schools benefited from better-trained teachers across two consecutive school years. The training shifted teachers away from emphasizing rote memorization toward stressing active, hands-on learning that connects children's intuitions about quantity to formal math.
Though they targeted completely different people, both programs shared one philosophy: children learn math best by actively exploring patterns and quantities.
Each Program Worked, But Together They Didn't Add Up
Both programs, on their own, produced gains in math test scores compared to the control group. The size of the gains was comparable to other successful educational interventions.
Here's the twist: combining both programs produced no extra benefit. Children who got both improved about the same as getting just one. The two programs acted as substitutes, not complements.
The gains were largest where they mattered most. On basic skills like writing numbers, children in the control group already replied correctly to 87% of the questions, leaving little room to grow. On harder tasks—sequences, equations, word problems—they answered only 26% correctly, and that's where both programs delivered their biggest improvements.
The Bottom Line for Budgets
For policymakers watching every dollar, the cost numbers are revealing. The parental program cost just $20 per child, compared with $78 per child for the teacher program—about four times as much. Yet the two programs produced almost the same size of improvement in math scores. Put another way, each dollar spent on the parental program delivered more than three times as much learning as a dollar spent on the teacher program.
But trained teachers keep teaching new students year after year. Spreading that cost across future cohorts, the teacher program became at least as cost-effective as the parental one. The combined program, however, lost on every measure: it cost more while delivering no additional learning.
A Lesson in Focus
The central message is practical and slightly counterintuitive: concentrating resources on a single binding constraint—home or school—maximizes learning per dollar. The likely reason the combination didn't help is that both programs relax the same constraint. Once a child has good, active math instruction from either source, more of the same yields diminishing returns.
This doesn't mean that there are no synergies between home and school investments; complementarities might emerge across broader skills or longer horizons. But for governments deciding how to spend today, the lesson is clear: whether you empower parents or transform teaching, either path works—and doing one thing well may be the smartest investment of all.
Keywords:
Research and Development