Language-in-education policies in Africa are believed to be a factor of poor quality education on the continent as languages learners are not conversant with continue to take the lead as languages of teaching and learning. This paper explores the experience of teachers and learners in Rwanda transitioning from Kinyarwanda to English as a medium of instruction in Grade Four and the implications thereof for teaching and learning. Data was collected from two public schools where two 'Social and Religious Studies' lessons were observed in each school: one in Grade Three and another in Grade Four. One Grade Four teacher from each school filled in a questionnaire and was interviewed. The analysis of the data followed thematic content analysis methods. The findings indicate that the transition is challenging for both teachers and learners due to their limited proficiency in English. Learners' engagement is very limited and teachers resort to unplanned code-switching, language pairing and content simplification. As a result, classroom interactions are dominated by drilled repetitions after the teacher, with extremely limited understanding a situation, which impedes learners' deep understanding and, de facto, access to quality education.