*3.4. Teaching of SUD in Practice*

The above perspectives on competencies, teaching, and learning aim to equip students with the knowledge and skills to go beyond traditional empirical understanding ("what" and "why" questions) to knowledge synthesis, normative questions, and ethical analysis ("how and "should" questions).

Urban areas are at the center of many of the key sustainability challenges and are where the complexity of these challenges becomes manifest. As such, cities are prime examples of the multifaceted nature of sustainability challenges, which do not neatly follow the disciplinary boundaries of traditional HEI departments (see [49]). Instead, they call for various forms of collaboration that extend beyond existing institutional structures. Therefore, urban issues are often the focus in ESD curricula [45–47]. Urban areas offer abundant real-world learning settings where students can obtain first-hand observations and experiences of sustainability challenges, combine scientific knowledge with local knowledge, and engage in collaboration and co-creation of solutions with stakeholders and experts from various fields. These settings encourage active, student-centered learning, critical, inter- and transdisciplinary thinking and flexible application of different problemsolving frameworks, which are integral to acquiring key sustainability competencies and contributing to sustainability-oriented societal transformations [35,46].

As global interest in sustainable development has increased, so have the number of higher education institutions offering degree programs on SUD [28,50–53]. However, often, the teaching of sustainability is integrated into existing curricula without a suitable

pedagogical framework based on ESD [19,54], and many existing programs—for example in urban studies and urban planning—are facing the challenge of embedding sustainability in their teaching [55]. While there is general agreement of the value of inter- and transdisciplinarity in addressing sustainability problems, integrating sustainability into new or existing courses and programs can be challenging and there can be multiple barriers [56]. For example, challenges remain as to how collaboration between disciplines can and should be fostered in practice. Coordinating teaching between different schools and disciplines while fostering interaction with the wider society entails balancing commitments to research, service, and teaching in various study programs, overcoming administrative and institutional challenges, and negotiating working definitions of "sustainability" and ways of assessing of student work [48,57].

Developing transdisciplinary curricula in practice is not without its significant challenges [58]. Teachers in HEIs have typically not been educated in an inter- or transdisciplinary manner themselves and lack the training to use such approaches in their teaching [59,60]. It requires close collaboration between academics from different disciplines, designing course learning objectives, curricula, lectures, and workshops. It also requires that academics have the time to learn about sustainability issues within their own fields, as well as an appreciation for the perspectives and knowledge of their academic collaborators. However, without embedded inter- or transdisciplinary approaches, sustainability is taught within disciplinary silos without broader perspectives.

In response to this, many institutions are opting to develop new interdisciplinary programs in SUD (e.g., [28,51–53]), while there are fewer but increasing numbers of transdisciplinary courses (e.g., [61]). This trend is also apparent in the field of urban studies, which has witnessed the emergence of new master's and bachelor's degree programs. So far, research on inter- and transdisciplinary learning and teaching in the urban context has mostly focused on individual university courses (e.g., [45,46,48,62]) or their institutional settings [19] instead of entirely new study programs in SUD. The majority of existing interand transdisciplinary SUD degree programs are at postgraduate level, and there are a limited number of undergraduate degree programs on sustainable urban development that can provide students with different perspectives on sustainable development prior to establishing their disciplinary expertise.
