When learners cannot access education in a language they already understand, whether their mother tongue or one from their community, it can make it harder for them to learn, hindering their access to and progression through education. When taught in their mother tongue, proficiency in their mother tongue improves, and so does the acquisition of foundational language skills that can be used across languages—the building blocks of reading—as well as foundational numeracy skills. This blog gives two examples from Viet Nam and Cameroon.