Integrating Education for Sustainable Development (ESD) into Science, Technology, Engineering, and Mathematics (STEM) teacher education is vital for preparing future educators to tackle the sustainability challenges of the 21st century. ESD is a holistic and transformative approach that enhances the quality of education through the development of competencies that promote the sustainability of present and future generations. ESD empowers learners to make informed decisions and take responsible actions for environmental integrity, economic viability, and social justice while respecting cultural diversity. Consequently, embedding ESD in teacher education is essential for equipping educators with the necessary knowledge, skills, values, and attitudes for sustainable living. Inadequate integration of ESD in teacher education limits prospective teachers' ability to instill sustainability-oriented thinking, values, and action in learners.

This study investigated the integration of ESD principles into STEM teacher training curricula at a South African university. It used a qualitative case study design based on UNESCO’s ESD framework, which emphasizes the integration of key sustainable development principles into education. The framework encompasses three main components: cross-cutting key ESD competencies, Sustainable Development Goals (SDG)-specific learning objectives, and transformative pedagogies. SDG-specific learning objectives are framed within cognitive, socio-emotional, and behavioral learning domains.

The following questions were investigated:
1. Which ESD principles are incorporated into the university's STEM teacher training programs?
2. What gaps and opportunities exist for integrating ESD into these programs?

Data were collected through the analysis of five course outlines, ten assessment tasks, and semi-structured interviews with five STEM teacher education lecturers. The findings indicate that although lecturers believe they incorporate Education for Sustainable Development (ESD) in their teaching, the reviewed documents primarily focus on a few cross-cutting key competencies like systems thinking, critical reflection, problem-solving, and technology use. The documents also contain evidence of SDG-specific learning objectives related to climate change, biodiversity, agriculture, atmosphere, poverty, and human health, but objectives related to the socio-emotional and behavioral domains are largely missing.

The predominant pedagogies were learner-centered, including inquiry-based, problem-based, project-based, and collaborative learning, while those that are action-oriented and participatory are lacking. The study also identified barriers to ESD integration, such as inadequate lecturer training, limited institutional support, and a lack of clear curriculum policy. Opportunities for improvement were also noted, including professional teacher development to enhance ESD competencies, curriculum revisions for clearer ESD outcomes, and supportive policies for sustainability education in STEM.

Based on these findings, we recommend targeted training for STEM lecturers, particularly regarding socio-emotional and behavioral aspects of ESD, and advocate for curriculum and policy reforms to systematically embed ESD in teacher education. This research contributes to the discourse on sustainable education in higher education and highlights gaps in the implementation of ESD that could guide curriculum design.

Keywords: Integration, education, sustainable development, curricula, STEM, teacher training.