This study explored Grade 3 teachers' use of an inquiry-based approach to mediate the development of basic science concepts among learners within the socio-cultural theory. This study adopted interpretive case study research of the qualitative type, using a sample of four (4) female teachers who use the home language of learners as the language of instruction. Data were collected using a semi-structured interview guide and observational schedule which was properly validated. Analysis of data was achieved through thematic data analysis. The result of the study revealed that the foundation phase teachers are aware of the importance of the use of the inquiry-based approach in mediating the development of basic science concepts by the learners, but only one out of the four participants implemented it. Thus, it was recommended that there should be a provision of further professional development spaces that promote a community of practice in using an Inquiry-Based Approach in the Foundation Phase.