**Abstract**

There are several challenges in teaching of concepts of Natural Sciences as a subject to isiXhosa speakers in primary schools in South Africa. This chapter explores the challenges of teaching Sciences Natural in English to isiXhosa speakers in the selected primary schools. The Bronfenbrenner's ecological systems theory was utilised. A qualitative research methodology was employed supported by the case study design. A purposeful sampling technique was utilised to select five different primary schools. Qualitative data were collected through semi-structured interviews and analysed thematically. This study revealed that Natural Sciences teachers use code switching for students to understand the scientific concepts that seem difficult to comprehend in English as a foreign language. Natural Sciences teachers indicated that policy makers do not involve them when planning the curriculum. The study recommends: (i) the curriculum to make a provision for teachers to start their lessons with what students are familiar with, (ii) Natural Sciences teachers to be familiar with the theories of language development for them to link the language with learning and teaching of Natural Sciences concepts through professional development programmes and workshops, and (iii) the Department of Education to ensure that it adopts the mother tongue policy for teaching Natural Sciences.

**Keywords:** Natural Sciences, teaching, concepts, English, second language
