In English-medium instruction (EMI), English-as-a-second-language students will learn all/some subjects through English. Although there are a considerable number of studies which explore classroom interaction in Hong Kong (HK) secondary EMI schools, few studies have investigated EMI lessons which involve South Asian ethnic minorised students. These students share different linguistic and cultural backgrounds and they may not share a common first language with the teacher and other classmates. This study conducts a multimodal conversation analysis of science and mathematics lessons at a HK EMI secondary school, triangulated with interview data, in order to explore how the EMI teacher mobilises various resources to make discipline-specific knowledge accessible and cater for the different needs of all students in the classroom. This study argues that the process of enacting inclusive practices is a process of translanguaging which requires the EMI teacher to mobilise various available multilingual and semiotic resources and draw on what students know collectively for transcending cultural boundaries from the students' everyday culture to cultures of school science and mathematics.