This paper reports on the classroom languaging practices of a group of science teachers in rural and township schools in South Africa where the majority of learners learn through the medium of English, despite the fact that it is the home language of only a small minority; and learners' poor English proficiency frequently restricts their access to the curriculum. The purpose of the study was to explore how these science teachers utilised the linguistic resources of the classroom--the learners' home language and English--and if their practices might improve learners' opportunity to learn science. A series of lessons for each teacher was videotaped and the teachers were interviewed on their language attitudes and practices. The focus is on one teacher, who demonstrated a skilled "bridging discourse" across modes, discourses and languages to provide learners with what appeared to be improved opportunities to learn science. What distinguished this teacher's practice from that of the other teachers was his systematic and purposeful use of the learners' home language in what has been termed "pedagogical translanguaging" as opposed to the relatively brief and reactive code-switching or complete avoidance of the learners' home language evident in the other classrooms.