The purpose of this study was to explore teachers’ perceptions of integrative STEM (science, technology, engineering, and mathematics) education within life sciences classrooms. To achieve this, a case study design was employed, involving three teachers from a single district in South Africa. The data collection methods included face-to-face interviews, analysis of lesson plans, and document examination. The collected data was then analyzed using thematic analysis. The study’s findings shed light on the existing challenges concerning the understanding and implementation of STEM education in life sciences classrooms. The teachers demonstrated limited understanding of STEM integration, mainly through the utilization of models. However, the predominant approach observed was traditional teacher-centered methods, which hindered the promotion of critical thinking among students. As a result, this study emphasizes the need for practical implications in terms of teacher professional development. It highlights the importance of higher education training institutions providing ample opportunities for teachers to enhance their ability to effectively implement integrated STEM education in their classrooms. By addressing these issues, educators can create more engaging and stimulating learning experiences that encourage critical thinking and foster a deeper understanding of STEM concepts among students.