摘要:AbstractTeachers are non-native speakers of English need to deliver appropriate content to their learners. The extent that they actually managed to deliver the content warranted phenomenon worthy of exploration. To what extent do non- native speakers of English had meaningfully delivered the Mathematics and Science lesson contents to their students who were themselves were non-native speakers of English? The purposes of this study were to identify and document teacher practices in Content-Based Instruction (CBI) in secondary schools, and to ascertain teachers’ reasons for adopting their CBI practices within their classrooms. The participants were mathematics and science teachers who were purposely selected. Nevertheless, their selection was based on the recommendation made by the State Education Department. Video recordings of lessons (mathematics and science) and stimulated recall technique were used, whereby teachers watched their teaching videos / episodes and justified their action within the classrooms. The teachers actual words uttered while teaching were different from what they had actually intended to communicate during the classroom discourse. Teachers’ actual explanation was unclear due to wrong selection of precise words during the explanation in the classroom discourse. The teachers felt that their classroom discourse were not successful to evoke students, meaningful learning of the lesson content. Teachers usually need to think about the content in Malay and they need to be sufficiently quick to translate from Malay to English, hence possess skill in code-switching. The teachers realized that their “quality of communicating the lesson content is questionable”. They agreed that the teachers are partly to be blamed for how the students had interpreted our explanations.