This blog about the world’s first wartime randomized controlled trial, conducted by Teach For Ukraine in partnership with the World Bank, was written by Lelys Dinarte-Diaz, a research economist in the Human Development Team of the World Bank’s Development Research Group, in co-authorship with Renata Lemos, James Gresham, Rony Rodríguez-Ramírez, and Harry A. Patrinos.
Lelys’s main research interests are development economics and the economics of education, with a focus on violence and crime. She uses experimental methods to study the impacts of psychology-based interventions on mental health outcomes. She has research projects in El Salvador, Guatemala, Honduras, Mexico, Jamaica, Peru, and Ecuador. She earned her Ph.D. and master’s degrees in economics from Pontificia Universidad Católica de Chile and her B.A. in Economics from ESEN in El Salvador, the country where she was born and raised.

Wars devastate infrastructure and institutions, but their most profound costs are often borne by human capital. Education systems are among the first casualties of conflict: schools are destroyed, and families are displaced, cutting off access to schooling and remaining services. At the same time, governments divert education funding to military or emergency needs, causing investment in education to decline precisely when children need it most.
During Russia’s invasion of Ukraine, government spending on education fell from 17 percent of total expenditure in 2021 to just 7 percent in 2023, while between 2,900 and 3,500 schools were damaged or destroyed. By late 2022, only 30 percent of secondary schools were able to operate fully in person, while 34 percent moved entirely online and 36 percent adopted blended approaches. Despite these adaptations, Ukrainian students faced large learning losses. In 2022, Ukrainian students scored 428 in reading and 441 in mathematics on the PISA assessment, well below the OECD averages.
Underinvestment in education and other social services during conflict is often treated as unavoidable.
The risk of infrastructure destruction, service disruption, and population displacement makes the delivery of public social services incredibly challenging and the returns on these investments uncertain. As a result, there is limited experimental evidence on interventions implemented during conflicts that can mitigate the adverse effects of war on human capital.
In our recent working paper, we study an online tutoring program as an example of an educational investment that can be implemented during conflict. While tutoring programs have proven effective in non-war settings (Nickow et al., 2023; Gortazar et al., 2024; Carlana and LaFerrara, 2025), it is unclear whether the key components determining their impact hold up in wartime conditions.
First, logistical challenges such as power outages and frequent displacement may hinder participation. Yet, students’ intrinsic motivation to recover lost learning may lead to high engagement despite adverse conditions. Second, the mechanisms through which tutoring operates may function differently during wartime. For example, structured peer interactions may both provide emotional support and facilitate learning, but they may also transmit stress or introduce distractions. Third, the broader context can moderate program impacts: the psychological toll of conflict may impair students’ ability to focus and reduce parents’ capacity to support their education.
Teach for Ukraine ran the online tutoring program as three consecutive experiments between early 2023 and mid-2024, each lasting six weeks.
The program offered small-group tutoring in math and Ukrainian language for three hours a week and was adapted to the evolving context each time: the first, launched amid winter power outages, focused on core academic catch-up; the second introduced diagnostic tools to group students by ability and better support tutors; and the third incorporated psychosocial support through trauma-informed care exercises in response to students’ growing mental health needs.

















