This article explores teachers' knowledge and views on the role of learners' socio-cultural background when teaching Natural Sciences to Grade 9 learners at three South African township schools. Within a socio-cultural framework, the research investigated how teachers accommodate learners' cultural norms and values, religion and beliefs, socio-economic and political issues in their science lessons. In a qualitative case study, three teachers were interviewed five times using a semi-structured interview schedule. Through a constant comparative data analysis method, three themes emerged. Firstly, teachers were aware of the learners' poor socio-economic background, and they made accommodation in their practice so that these learners would not be disadvantaged. Secondly, it emerged that teachers use their knowledge about learners' socio-cultural practices and beliefs, to create learning opportunities to harmonise the conflict between learners' worldviews and science. Lastly, the findings showed that teachers' incorporation of learners' socio-cultural background in lessons provides authentic learning situations that promoted the development of critical and analytical thinking skills in learners. This study affirms the call for teacher education institutions to review their science teacher education programmes with a view to incorporating and emphasising knowledge of learners' socio-cultural background as an important teacher knowledge domain in teacher preparation.