Despite less than 10% of South Africans claiming English as their home language, it has become the de facto language of instruction. Yet we cannot assume that teachers have sufficient command of this language when using it for instructional purposes. As a sub-study, in this article we report on the oral proficiency of isiZulu-speaking pre-service teachers who use English when expounding content in rural schools. The conceptual framework draws primarily on research relating to instructional communication and Classroom English. For this mixed methods case study, using questionnaire data from 52 pre-service teachers and 18 tutors, we sought to establish the perceptions that respondents had of students' oral proficiency while teaching in situ. Responses were statistically analysed using computing software. Unedited audio recordings of lessons presented in rural KwaZulu-Natal schools during pre-service teachers' work-integrated learning stint provided oral data from which to gauge proficiency using a self-designed rubric. Findings correspond with those of previous studies, pointing to preservice teachers' oral proficiency being less than ideal for effectively facilitating learning. However, what is considered adequate proficiency and what is ideal is yet to be agreed upon. We recommend that interventions which address the development of oral proficiency required for classroom use be considered. Our pilot rubric may serve as a useful data-gathering tool in future research.