**1. Introduction**

Sustainable development is described by the United Nations Economic Commission for Europe (UNECE)'s Strategy for Education for Sustainable Development (ESD) as being underpinned by an ethic of solidarity, equality, and mutual respect among people, countries, cultures and generations. ESD is development in harmony with nature and meeting the needs of the present generation without compromising the ability of future generations to meet their own needs [1]. It empowers people to change their way of thinking and to work towards a sustainable future. Knowledge, skills, and attitudes to managing sustainable development are under the spotlight in all types of education because they are needed for future agents in the field of sustainable development [2,3]. ESD aims to develop competences that enable and empower individuals to reflect on their own actions by taking into account their current and future social, cultural, economic and environmental issues. ESD is designed for local and global perspectives, acts in complex situations in a sustainable manner—which may require the individual to strike out in new directions—and participates in socio-political processes moving societies towards sustainable development.

The global challenges facing contemporary society call for viable strategies and prompt action to address individual and collective issues and challenges, as well as their approaches to tackling them. To do so requires observing and understanding the viewpoint and complexity of the educational systems; as represented in the United Nations 2016 Sustainable Development Goals (SDGs) to be achieved in 2030. However, less than one decade remains in which to establish and facilitate education frameworks for citizenship awareness and participation, and develop new ways of knowledge production and decision-making with respect to sustainability. Efforts should be channelled towards (i) validating different didactic strategies and approaches to address sustainability from a constructivist and pedagogical community [4], (ii) diagnosing the status of sustainability training needs for formal and/or non-formal education, (iii) identifying the sustainability competence levels of children and young people currently in educational centres across the board and (iv) developing and testing appropriate and effective educational activities and practices [5]. While a few studies have investigated the pedagogical approaches and their effects on sustainable competences [6–8], the research, however, still remains limited.

The process of education is characterised by cognitive contemplation, learning to manage processes through skills and active experimenting [4,6]. It is an individual process where students expand their knowledge and understanding, their skills and experiences, values and attitudes and develop these into social values [9–12]. This is an interactive process in which the students, as learners, examine their experiences, reflect on them through spontaneous or routine activities, discover and subconsciously construe new meanings and insights, and foresee new perspectives [11]; it is the process of integrating the previously available knowledge with the new, by putting their theoretical knowledge into practice [9,12]. Independent of what formal knowledge is provided in the education process, each student will model original understanding of the phenomenon or activities and will create and build their own theories to final understanding. Reflective learning, then, allows for students' personal growth to be observed and helps to foresee ways of developing teaching processes to encourage learning in, for instance, higher education institutions, among others [13,14].

Professional development is a person's capacity to continuously learn through their ability to reflect, to analyse their experiences in depth, to develop and substantiate knowledge, and to refresh and revaluate it. All this is in order to better know and manage themselves by diagnosing personal mistakes, and acquiring and developing efficient analytical skills for learning and about learning, through learning [13]. Reflection is directly linked with a practitioner's motivation for conscious activities, their modelling and adjustment; it indirectly determines the practitioner's empowerment for constant learning/development by assuming responsibility for their own actions and solutions [15–17]. The process of reflective learning is characterised by a transformative empowering of students for personal, unrestricted, independent activity by (i) analysing their own experiences and learning skills, (ii) relating theoretical knowledge to practical knowledge and developing skills to identify and solve problems and (iii) changing their attitudes and becoming more tolerant [18,19].

When reflection (as a component of reflective learning), deliberates on acquired experience, diagnosing one's own mistakes and learning from detailed analysis, only then does an open possibility for reform emerge from the professional experience which employs reflective thinking and refers to one's personal system of viewpoints, attitudes and values [20,21]. Reflection—as the premise of the educational transformation of experience for learning at primary, secondary and tertiary institutions—depends on the conditions provided for it. Conditions for reflective teaching and learning are created by developing the learner's competence to reflect, where individual experiences, thoughts, emotions and actions become the essential elements embedded in the ability to recognise the social and political contexts in which the individual lives and the values they want to keep to be inclusive, democratic, sustainable and social [22,23].
