In the early years of schooling, the language of instruction has a significant impact on academic success or failure. In Côte d'Ivoire, the majority of children begin their education in French, which is neither the language spoken at home nor in their community. This reality, which is often underestimated, has a significant impact on the acquisition of basic reading and math skills. To objectify this debate, the organization Teaching at the Right Level (TaRL) initiated a baseline study, with the support of CRIHD as a technical partner responsible for implementation and analysis. The study sought to understand how the gradual integration of local languages could improve understanding of fundamental concepts and enhance the effectiveness of primary education. The lessons learned are clear: when local languages are used in a structured and pedagogical manner, they facilitate knowledge acquisition, increase student participation, and reduce learning gaps from the earliest grades. Conversely, teaching exclusively in French, without any adaptation measures, tends to reproduce educational inequalities. The results of this study directly informed public policy, contributing to the adoption of a policy of including local languages in primary education and the extension of the program nationwide. It illustrates how applied research,
