Integration of the Concept and Dimensions of Sustainability into the Curricular Bases of Third Year (11th Grade) and Fourth Year (12th Grade) of Secondary Education in Chile

Abstract

Sustainability is a foundational principle in Chilean education, reflected in curricular objectives related to environmental care, economic development, and social well-being. This study analyzes the integration of sustainability concepts and dimensions into the curricular bases of the third year (11th grade) and fourth year (12th grade) in Chilean secondary education. Using a sequential explanatory mixed-methods design and content analysis, the quantitative phase identified six key sustainability-related terms and their presence across curricular components and subject areas. The qualitative phase examined the inclusion of the environmental, social, and economic dimensions within those areas. The results show that sustainability concepts appear in seven subject areas, with greater emphasis on learning objectives and educational purposes. However, the environmental dimension dominates, while the social and economic aspects are underrepresented. These findings reveal conceptual ambiguities and uneven integration, highlighting challenges for implementing a multidimensional sustainability approach in Chilean classrooms.

1. Introduction

The national curriculum defined by the Ministry of Education in Chile (MINEDUC) has incorporated the concept of sustainability across various curricular areas and educational levels [1]. In line with the policies of the United Nations (UN), the Chilean educational system has implemented this development model, defined as one that seeks to meet the needs of the present without compromising the ability of future generations to meet their own needs [1,2]. This concept has gained increasing importance in recent decades, standing out as a cross-cutting axis in global educational policies [3,4,5].

The General Education Law (LGE) establishes sustainability as one of the fundamental principles of education in Chile, inspired by respect for the environment and the rational use of natural resources [6]. However, there are multiple interpretations and a lack of semantic consistency regarding the concept of sustainability, which hinders its effective implementation [7]. This polysemy arises from the fact that the term sustainable development has been translated into Spanish as either desarrollo sostenible or desarrollo sustentable [8]. Depending on the predominant translation in each Spanish-speaking country, one term or the other is adopted, generating tensions in the educational field [9,10,11].

In Chile, the country where this research is conducted, the terms sustentabilidad and sostenibilidad are used interchangeably in some official documents [12,13]. However, the term sustentabilidad is the one mentioned as a fundamental principle of education in the LGE, and desarrollo sustentable is the term adopted by the Ministry of the Environment in its National Policy on Education for Sustainable Development. Based on this background, the present study adopts the concept of sustentabilidad, referring to the harmony among the economic, social, and environmental subsystems. This relates to the finite and limited nature of the planet and its resources, with an exponentially growing population that needs to produce and meet its needs in a clean manner without depleting resources. In contrast, sostenibilidad is more related to what can be sustained over time, and tends to consider the social, environmental, and economic subsystems separately [9].

Another relevant background for analyzing the incorporation of sustainability into the national curriculum relates to the integration of its essential dimensions. In this regard, various authors [1,3,4,9,14,15] argue that the goal of sustainable development is to balance and integrate three fundamental dimensions or pillars: environment, society, and economy.

According to [3]:

• The environmental dimension addresses issues such as the preservation of natural resources and ensuring the natural functioning of local ecosystems and nature in general.
• The social dimension focuses on solidarity, cooperation, and respect among different communities.
• The economic dimension seeks to ensure quality of life through economic self-determination and self-development of both individuals and societies.

To clarify these dimensions, Dutch economist Peter Nijkamp proposes a graphic representation known as Nijkamp’s Triangle, which synthesizes sustainability as the relationship between economic growth, social equity, and environmental sustainability, giving rise to sustainable development at the center of the triangle, as shown in Figure 1. With the evolution of the concept of sustainable development, other dimensions or pillars have gained relevance. In this regard [16] argues that the UN’s 2030 Agenda for Sustainable Development introduces new economic, institutional, and legal dimensions in areas such as health, education, and circular economy, among others. However, this study focuses on the three essential dimensions: environment, economy, and society.

Within the global context of sustainable development, the 2030 Agenda has gained significant relevance. This global agenda establishes seventeen Sustainable Development Goals (SDGs) that integrate and balance the social, economic, and environmental dimensions. These goals were adopted by world leaders to eradicate poverty, protect the planet, and ensure prosperity for all [3]. In the Chilean context, since the 1990s, various institutional programs have been implemented under the guidelines of the UN and UNESCO. For example, the National Energy Efficiency Program aims to promote sustainable energy development in Chile by educating and raising awareness about efficient energy use. Additionally, a National Environmental Certification System for Educational Institutions (SNCAE) has been launched, addressing environmental education for sustainability in schools across the country [1]. Furthermore, in 2009, the National Policy on Education for Sustainable Development was established, aiming to integrate sustainability principles at all educational levels through a holistic and cross-cutting approach, with methodological guidelines for implementing sustainability in Chilean classrooms [13].

Despite these efforts, initiatives and studies on the integration of the concept and dimensions of sustainability in the Chilean curriculum remain scarce. Even with the growing importance of the global agenda for sustainable development, there is still no consensus on the conceptual framework associated with this development model in Spanish-speaking countries. For instance, in the context of international educational policies, the terms sustainable, sustainable development, and sustainability appear more frequently, as seen in the UN’s SDGs and UNESCO’s Education for Sustainable Development program [5]. In contrast, the Chilean literature more commonly uses the terms sustentable, desarrollo sustentable, and sustentabilidad [8,13]. These same terms appear in Chile’s Environmental Framework Law No. 19.300 [17] and the General Education Law No. 20.370 [6]. These conceptual ambiguities surrounding sustainability ultimately hinder the development of a comprehensive and coherent educational approach in Chile, as well as in other Spanish-speaking countries.

Regarding the integration of the three essential dimensions, recent research on the role of sustainability across various levels of the Chilean curriculum suggests that in early childhood education, there is a marked emphasis on the environmental dimension over the social and economic ones [15]. In primary education, sustainability is not strongly present, with opportunities emerging mainly in natural and social sciences when linked to environmental topics [18]. Another study analyzing the curriculum from the Seventh Year (7th grade) through to the Second Year of secondary education (10th grade) in Chile identifies sustainability in four subject areas: Natural Sciences and Arts primarily focus on the environmental dimension, while Technology and History, Geography, and Social Sciences address the three essential dimensions in a more holistic and integrated manner [1]. However, no such analyses exist for the most recent 2019 curricular bases for the third year (11th grade) and fourth year (12th grade).

The curricular bases have been established by MINEDUC [12] from early childhood to secondary education, aiming to ensure educational quality nationwide and provide a shared cultural foundation for the country. These are the main documents of the national curriculum to fulfil the mission of offering a common cultural base through:

• Learning objectives: defined for each grade or level, referring to the skills, attitudes, and knowledge intended to support students’ holistic development.
• Educational purposes: define the educational goals to be achieved through the learning objectives.
• Subject approach: explains the main concepts, theories, and disciplinary principles upon which the subject’s learning is based.

Thus, the curricular bases have undergone significant updates since 2011, beginning with the First through Sixth Year of Primary Education (first to sixth grade). In 2015, the revisions were extended to encompass the Seventh Year (7th grade) through the Second Year of secondary education (10th grade). Finally, in 2019, the curricular bases for the 11th and 12th grades were updated [19], for which no studies are known to analyze the integration of the concept and dimensions of sustainability in these documents.

The curriculum for the 11th and 12th grades in Chile aims for students to “expand and deepen their general education and develop the knowledge, skills, and attitudes that enable them to exercise active citizenship and integrate into society,” and “guide students to continue their formal educational process through higher education or enter the workforce” [12]. According to MINEDUC, with these curricular bases, “the goal is to educate citizens with critical thinking, effective and efficient communication skills, adaptability, flexibility, creativity, participation in democratic institutions, respect for diversity and multiculturalism, self-empowerment, and healthy self-esteem. In this way, they will be able to make informed, reasoned, and independent decisions, develop their potential, and live fulfilling lives, actively participating in a free, democratic, and pluralistic society, and contributing responsibly to the sustainable and equitable development of the country” [12].

As presented in the previous paragraphs, some programs and curricular reforms in Chile have incorporated elements related to sustainability. However, questions remain regarding the depth, coherence, and effective implementation of this development model in Chilean classrooms. Likewise, it is still unclear how the social, environmental, and economic dimensions are integrated, particularly in the final two years of secondary education. Therefore, the main objective of this study is to analyze the integration of the concept and dimensions of sustainability into the curricular bases of the third year (11th grade) and fourth year (12th grade) of secondary education in Chile.

The specific objectives of this study are as follows:

• To identify the frequency with which the key concepts sustainable, sustainability, and sustainable development, and their Spanish equivalents sustentable, sustentabilidad, and desarrollo sustentable appear in the curricular bases of the third year (11th grade) and fourth year (12th grade) of secondary education in Chile.
• To distinguish the curricular areas that incorporate these key concepts in the curricular bases of the third year (11th grade) and fourth year (12th grade) of secondary education in Chile.
• To determine the curricular component into which the concept is integrated, whether in learning objectives, subject approach, or educational purposes, within the third year (11th grade) and fourth year (12th grade) of secondary education in Chile.
• To determine the presence and/or absence of the three essential dimensions of sustainability environment, economy, and society within the curricular areas of the third year (11th grade) and fourth year (12th grade) of secondary education in Chile.

2. Methodology

Based on the above, this mixed-methods research followed a sequential explanatory design (DEXPLIS) [20].

In the first stage, the quantitative method was used to collect information on the frequency of key concepts: (a) sustainability (from Spanish: sustentabilidad), (b) sustainable development (from Spanish: desarrollo sostenible), (c) sustainability (from Spanish: sostenibilidad), (d) sustainable (from Spanish: sustentable), (e) sustainable (from Spanish: sostenible), and (f) sustainable development (from Spanish: desarrollo sustentable) in the curricular bases of the third year (11th grade) and fourth year (12th grade) of secondary education in Chile. This stage also identified the curricular areas in which these concepts appear, considering both the General Education Common Plan and the Elective Plan [12]. Finally, the key concepts were categorized according to their presence in learning objectives, subject approach, or educational purposes.

• In the Chilean context as well as in broader Spanish-speaking regions, particularly in Latin America, the terms sostenibilidad and sustentabilidad are often used as distinct expressions. However, both refer to the same overarching concept: the balanced integration of environmental protection, economic development, and social equity. For the purposes of this study, both terms are treated as equivalent and are translated into English as sustainability.
• In the second stage, the qualitative method was used to determine the presence or absence of the three essential dimensions of sustainability environment, economy, and society. This stage focused on the textual paragraphs where the key concepts were found, based on the data collected and evaluated in the first stage [20].

The document analysis technique allows for the development of an instrument based on the research objectives, incorporating both quantitative and qualitative data sequentially [21]. The data collection instrument consisted of a matrix for recording the keywords related to sustainability, the page number of the curricular bases for the third and fourth years of secondary education, and their classification according to the curricular area, the curricular component (learning objective, educational purpose, or subject approach), and the specific paragraph in which the keyword appears. To clarify the matrix records,

Table 1. Concept associated with sustainability, curricular area, and curricular component in the curricular bases of the third year (11th grade) and fourth year (12th grade) of secondary education in Chile [12].

N°	Concept	Curricular Area	Curricular Component	Text	Page
1	Desarrollo sostenible (in English: Sustainable Development)	Ciencias para la Ciudadanía (in English: Science for Citizenship).	Subject Approaches	Generar conocimiento científico y desarrollo tecnológico en el marco del desarrollo sostenible es fundamental para el bienestar futuro de la sociedad, pues las innovaciones en este ámbito permitirán avanzar en medidas apropiadas de conservación y protección del ambiente.	45
2	Sostenibilidad (in English: Sustainability)	Ciencias para la Ciudadanía (in English: Science for Citizenship).	Subject Approaches	La asignatura Ciencias para la Ciudadanía se imparte por medio de cuatro módulos temáticos: 1. Bienestar y salud 2. Seguridad, prevención y autocuidado 3. Ambiente y sostenibilidad 4. Tecnología y sociedad	47
3	Sostenibilidad (in English: Sustainability)	Ciencias para la Ciudadanía (in English: Science for Citizenship).	Learning objectives	Ambiente y sostenibilidad	52
4	Sostenible (in English: Sustainable)	Ciencias para la Ciudadanía (in English: Science for Citizenship).	Learning objectives	Investigar el ciclo de vida de productos de uso cotidiano y proponer, basados en evidencia, estrategias de consumo sostenible para prevenir y mitigar impactos ambientales.	52
5	Sostenible (in English: Sustainable)	Ciencias para la Ciudadanía (in English; Science for Citizenship).	Learning objectives	Diseñar proyectos locales, basados en evidencia científica, para la protección y utilización sostenible de recursos naturales de Chile, considerando eficiencia energética, reducción de emisiones, tratamiento de recursos hídricos, conservación de ecosistemas o gestión de residuos, entre otros	52
6	Desarrollo sustentable (in English: Sustainable Development)	Educación Ciudadana (in English: Citizenship Education).	Formative purpose	La asignatura Educación Ciudadana tiene por objetivo desarrollar un conjunto de conocimientos, habilidades y actitudes para que los estudiantes conozcan el sistema democrático y se desenvuelvan en él, participando en forma activa y corresponsable en la construcción de una sociedad orientada hacia el fortalecimiento del bien común, la justicia social y el desarrollo sustentable.	54

Note: prepared by the authors.

is provided below. The content analysis technique was used to carry out this work [1]. This type of analysis is justified because the aim is not to analyze the style of the curricular text, but rather the ideas expressed in it [22]. The focus is on quantifying the meaning of words, themes, or phrases.

The analysis stages correspond to the following six steps.

2.1. Document Selection

No human participants were involved in this study. The documents selected for analysis were the curricular bases of the third year (11th grade) and fourth year (12th grade) of secondary education in Chile. This document was chosen as it represents the main national curriculum framework, grounded in the Chilean Constitution and educational proposal [12]. The curricular areas included in the curricular bases for these levels are structured within the General Education Plan. Within the General Education Common Plan, the curricular areas include Sciences for Citizenship, Civic Education, Philosophy, English, Language and Literature, and Mathematics. Within the Elective General Education Common Plan, the areas include Arts, Physical Education and Health, and History, Geography and Social Sciences [12].

As an exclusion criterion in the first phase, key concepts appearing in the following sections were not considered: introduction, bibliography, annexes, and glossaries. The focus was placed on the curricular areas of the General Education Plan and the Elective General Education Common Plan for the third and fourth years. In the second stage, a second exclusion criterion was applied to disregard texts corresponding to titles or those that do not provide relevant content for determining the presence or absence of the sustainability dimensions under study.

2.2. Preliminary Reading

An overview of the document was conducted to assess its relevance to the research objectives. Initially, the curricular bases for the third and fourth years were read to become familiar with the content and structure, highlighting sections relevant to the study. This process helped define the pre-established categories and units of analysis.

2.3. Coding

In the quantitative stage, the pre-established categories were defined as all Spanish-language terms related to sustainability:

• Sustentabilidad (in English: Sustainability).
• Sostenibilidad (in English: Sustainability).
• Sustentable (in English: Sustainable).
• Sostenible (in English: Sustainable).
• Desarrollo sostenible (in English: Sustainable development).
• Desarrollo sustentable (in English: Sustainable development).

Additionally, the units of analysis were defined as the curricular components of each subject or curricular area:

• Learning objectives.
• Educational purposes.
• Subject approach.

In the qualitative stage, the pre-established categories corresponded to the three essential dimensions of sustainability:

• Environment.
• Economy.
• Society.

2.4. Analysis and Interpretation

In the first stage of the study, quantitative analysis was conducted using descriptive statistics to examine the presence and distribution of key sustainability-related concepts within the curriculum documents. This process involved counting the absolute frequency of each term, that is, the number of times each concept appeared in the texts and calculating the corresponding percentages based on the total number of recorded occurrences. These percentages allowed for relative comparisons across concepts and curricular areas, providing insight into the prominence and placement of sustainability-related terminology throughout the curriculum.

The statistical methods used in the quantitative stage included the following:

a. Absolute frequency: Counting the number of times key concepts appeared in the document, with and without applying the exclusion criteria.

b. Relative frequency: The percentage of each term’s appearance in relation to the total number of terms analyzed after applying the exclusion criteria.

c. Percentage: The proportion of key concepts appearing in relation to curricular components or pre-established categories (learning objectives, educational purposes, and subject approach).

In the second stage, a qualitative analysis was conducted, as the data were filtered based on the researcher’s judgment [22]. Textual paragraphs containing the keywords were analyzed to determine the presence or absence of the fundamental dimensions in each text. This information was then expressed as a percentage for better interpretation. The percentage represents the proportion of each dimension present in relation to the total number of textual paragraphs analyzed. Additionally, the frequency of the three essential dimensions was established for each curricular area that incorporated sustainability.

2.5. Triangulation

Once the data were analyzed and interpreted, they were grouped, compared, and contrasted to identify possible patterns or alignments across the studied curricular areas, as well as within the pre-established categories and units of analysis.

2.6. Writing of Results

Finally, the quantitative results were presented first, followed by the qualitative results, both structured according to the previously described methodology.

3. Results

The concepts of sustainability (in Spanish: sustentabilidad), sustainable development (in Spanish: desarrollo sostenible), sustainability (in Spanish: sostenibilidad), sustainable (in Spanish: sustentable), sustainable (in Spanish: sostenible) and sustainable development (in Spanish: desarrollo sustentable) were identified a total of 45 times throughout the document corresponding to the curricular bases of the third year (11th grade) and fourth year (12th grade) of secondary education in Chile. After applying the exclusion criteria, a total of 27 occurrences of the key concepts were recorded. Each of the sustainability-related concepts and their frequency are presented in

Table 2. Frequency of Key Concepts in the Curricular Bases of the Third Year (11th grade) and Fourth Year (12th grade) of secondary education.

Key Concepts	Frequency (f)	Proportion (p)	Percentage (%)
Sustentabilidad (in English: Sustainability)	14	0.519	51.9
Desarrollo sostenible (in English: Sustainable Development)	6	0.222	22.2
Sostenibilidad (in English: Sustainability)	3	0.111	11.1
Sustentable (in English: Sustainable)	3	0.111	11.1
Sostenible (in English: Sustainable)	1	0.037	3.7
Desarrollo sustentable (in English: Sustainable Development)	0	0	0
Result	n = 27	n = 1	n = 100

Note: prepared by the authors.

.

Regarding the frequency of key concepts according to the curricular areas of the third year (11th grade) and fourth year (12th grade) that incorporate sustainability-related terms, Figure 2 shows that the curricular areas of Civic Education; History, Geography and Social Sciences; Arts; and Physical Education and Health use the terms sustainability (in Spanish: sustentabilidad) or sustainable (in Spanish: sustentable). On the other hand, the curricular areas of Science and Sciences for Citizenship use the terms sustainable development (in Spanish: desarrollo sostenible), sustainable (in Spanish: sostenible), or sustainability (in Spanish: sostenibilidad).

Regarding the curricular components in which the concept of sustainability and its related terms are detected, these correspond to learning objectives (44.4%), followed by educational objectives (40.7%), and finally subject focus (14.8%) (see Figure 3).

The following results correspond to the presence of sustainability dimensions across all curriculum areas studied in the curriculum bases for the third year (11th grade) and fourth year (12th grade) of secondary education in Chile (see Figure 4). After applying the second exclusion criterion, a frequency of 24 occurrences of sustainability-related concepts was identified in those textual paragraphs that provide sufficient information to determine the presence or absence of the three essential dimensions. Additionally, the frequency of the environmental (see

Table 3. Frequency of Occurrence of the Environmental Dimension in the Curriculum Areas of Third Year (11th grade) and Fourth Year (12th grade) [12].

Curriculum Area	Analyzed Texts	Frequency (f) Environmental Dimension
Ciencias para la Ciudadanía (in English: Science for citizenship).	3	3
Educación Ciudadana (in English: Civic Education)	5	2
Historia, geografía y ciencias sociales (in English: History, Geography, and Social Sciences).	2	1
Artes (in English: Arts).	4	4
Ciencias (in English: Science).	5	5
Educación Física y Salud (in English: Physical Education and Health).	1	1
Historia, geografía y ciencias sociales con plan diferenciado (in English: History, Geography, and Social Sciences (Elective Track).	4	3
Result	24	19

Note: prepared by the authors.

), economic (see

Table 4. Frequency of Occurrence of the Economic Dimension in the Curriculum Areas of Third Year (11th grade) and Fourth Year (12th grade) [12].

Curriculum Area	Analyzed Texts	Frequency (f) Economic Dimension
Ciencias para la Ciudadanía (in English: Science for Citizenship).	3	2
Educación Ciudadana (in English: Civic Education).	5	2
Historia, geografía y ciencias sociales (in English: History, Geography, and Social Sciences).	2	0
Artes (in English: Arts).	4	0
Ciencias (in English: Science).	5	0
Educación Física y Salud (in English: Physical Education and Health).	1	0
Historia, geografía y ciencias sociales con plan diferenciado (in English: History, Geography, and Social Sciences (Elective Track).	4	1
Result	24	5

Note: prepared by the authors.

), and social dimensions (see

Table 5. Frequency of Occurrence of the Social Dimension in the Curriculum Areas of Third Year (11th grade) and Fourth Year (12th grade) (MINEDUC, 2019 [12]).

Curriculum Area	Analyzed Texts	Frequency (f) Social Dimension
Ciencias para la Ciudadanía (in English: Science for citizenship).	3	0
Educación Ciudadana (in English: Civic Education).	5	3
Historia, geografía y ciencias sociales (in English: History, Geography, and Social Sciences).	2	1
Artes (in English: Arts).	4	0
Ciencias (in English: Science).	5	1
Educación Física y Salud (in English: Physical Education and Health).	1	1
Historia, geografía y ciencias sociales con plan diferenciado (in English: History, Geography, and Social Sciences (Elective Track).	4	3
Result	24	9

Note: prepared by the authors.

) is highlighted for each curriculum area within the General Education Plan and the Common Elective General Education Plan for Third and Fourth Year,).

A summary of the main results by each dimension is presented below:

• Environmental Dimension: Represents a proportion of 58%. It was observed that terms related to environmental sustainability, such as “environment,” “climate change,” and “natural resources” are the most frequent. The curriculum areas that place the greatest emphasis on this dimension are Science and Arts.
• Economic Dimension: Represents a proportion of 15%. The term most frequently associated with economic sustainability was “equity,” and the curriculum areas that emphasize this dimension the most are Science for Citizenship and Civic Education.
• Social Dimension: Represents a proportion of 27%. The most frequent term related to social sustainability was “well-being,” and the curriculum areas that emphasize this dimension the most are History, Geography, and Social Sciences and Civic Education.

4. Discussion

The results regarding the appearance of the concepts: sustainability (in Spanish: sustentabilidad), sustainable development (in Spanish: desarrollo sostenible), sustainability (in Spanish: sostenibilidad), sustainable (in Spanish: sustentable), sustainable (in Spanish: sostenible), and sustainable development (in Spanish: desarrollo sustentable) in the curriculum bases for the third year (11th grade) and Fourth Year (12th grade) in Chile show that the most frequently used concepts are sustainability (in Spanish: sustentabilidad) along with its conjugation sustainable (in Spanish: sustentable), followed by the concepts of sustainable development (in Spanish: desarrollo sostenible) and sustainability (in Spanish: sostenibilidad), which are the most commonly adopted by international policies [4,5,23].

The greater prevalence of the concept of sustainability (in Spanish: sustentabilidad) aligns with evidence in Chile from various studies and official documents, where this concept is predominant [8,13,15].

Regarding the curriculum areas that use the term sustentabilidad (in Spanish: sustentabilidad), these correspond to History, Geography, and Social Sciences; Arts; Physical Education and Health; and Civic Education. In contrast, in the curriculum areas of Science and Science for Citizenship, the concepts of sustainable (in Spanish: sostenible) and sustainability (in Spanish: sostenibilidad) are used, suggesting that these subjects may be more aligned with international policies from the UN and UNESCO.

The analysis of the results regarding the different curricular contexts (learning objectives, educational purposes, and subject approach) in which the key concepts are used shows that the majority correspond to learning objectives (44.4%), followed by educational purposes (40.7%). According to MINEDUC, 2019 [12], learning objectives “define the expected terminal learning outcomes for a given subject in each school year,” so the appearance of sustainability in these objectives indicates that the curriculum for 11th and 12th grade aims to provide learning that contributes to the formation of citizens that are aware of environmental, social, and economic issues [1,15].

As for the educational purposes, these explain the reason for learning and are therefore also important for the curriculum to form citizens with critical thinking, active participation in democratic institutions, respect for diversity and multiculturalism, and who contribute responsibly to the sustainable and equitable development of the country [12].

The results regarding the dimensions of sustainability reveal a predominant emphasis on the environmental dimension. Such an unequal representation hinders the understanding of sustainability as a cross-cutting and integrative model of development, in which economic growth should ensure adequate goods and services for the population, promote social equity and civic participation, and prevent poverty and economic inequality [9]. Consequently, the limited presence of the social and economic dimensions reflects a partial view of sustainability in the national curriculum for the final years of secondary education.

Comparisons with other studies in early childhood [15] and primary education [1] reveal a similar trend, with the environmental dimension prevailing over the others. This points to the need to review and balance the representation of the social, economic, and environmental dimensions across all educational levels to ensure a comprehensive understanding of the concept and to foster a holistic, multidimensional approach [3]. However, the objective is not to prioritize one specific dimension, but rather to interconnect them in an approach that challenges the current subject-based structure of the curriculum [1].

Although various educational initiatives related to sustainability have been developed in Chile, their effective implementation largely depends on the commitment of teachers and school leadership [8]. Despite the global commitment to education for sustainable development, evidence regarding its implementation in classrooms and its impact on student outcomes remains limited [24]. Therefore, it is crucial to continue researching and developing strategies that strengthen the integration of sustainability into the curriculum in a coherent and effective manner.

5. Pedagogical Implications and Active Strategies

To overcome a restricted, theory-based approach to teaching sustainability, it is possible to adopt a variety of active teaching strategies that enable the design and implementation of instructional processes incorporating environmental, economic, and social dimensions, thereby fostering a tangible impact on the community. We have compiled several strategies that have generated good practices in these areas:

• Project-Based Learning (PBL): PBL emerges as a highly effective teaching strategy [25]. Its main potential lies in enabling students to address real-world problem-solving, fostering deep learning and the development of sustainability competencies [26,27], with key skills including problem-solving, environmental awareness, and critical thinking [28,29]. A quasi-experimental study demonstrated that PBL significantly improved students’ knowledge, attitudes, and behaviors related to sustainability and energy conservation [30].
• Interdisciplinary Approaches: By nature, sustainability must be addressed with multiple dimensions. Interdisciplinary approaches are therefore essential, as they allow students to explore sustainability issues in a holistic rather than isolated manner [31,32]. For instance, in Croatian secondary schools, interdisciplinary lesson planning was successfully implemented, with teachers from different subjects collaborating to design relevant teaching processes on sustainable development [33].
• Critical and Systems Thinking: Developing critical and systems thinking is fundamental for students to analyze complex systems and develop innovative solutions [34]. Pedagogical strategies such as backcasting (desired future) and design thinking can effectively promote these competencies. A recent study concluded that these methods enhanced students’ capacity to envision themselves as active future citizens, capable of rigorously assessing social, environmental, and economic challenges, and thinking critically about the medium- and long-term effects and impacts of their actions, which is an essential skill for sustainable development [34].
• Other Active Methodologies: Cooperative learning and service-learning are methodologies that complement both PBL and interdisciplinary approaches. Cooperative learning fosters both individual and group responsibility, service-learning integrates community service with academic learning, promoting students’ ability to act autonomously, make informed decisions, and actively engage in their own learning processes and community participation [35]. The e-World project is a concrete example of how active methodologies can be applied to teaching sustainability topics, thereby increasing students’ awareness of critical global challenges. Such school-based implementations promote active citizenship and responsible environmental behavior [36].

Despite the potential of these strategies, their implementation faces challenges such as the time required, the difficulty of carrying out meaningful activities, and the experience level of teachers [15]. The integration of sustainability into curricula requires a holistic approach that addresses cognitive, affective, and procedural dimensions [32].

To make holistic sustainability education a reality in the Chilean school system, it is essential to do the following:

• Overcome curricular fragmentation: Progress must be made toward integrative curriculum approaches that promote connections between disciplines and contexts, facilitating a holistic understanding that is more suited to the multiple facets of sustainability [37,38].
• Strengthen initial teacher training and professional development: Professional development programs are essential to equip educators with the necessary knowledge and skills [39]. One of the major challenges is the lack of adequate teacher training, which limits their ability to integrate sustainability, particularly in certain educational levels such as Vocational Education, known in Chile as Enseñanza Media Técnico Profesional [40].
• Promote research and evaluation: It is crucial to investigate and develop strategies that strengthen the integration of sustainability into the curriculum in a coherent and effective manner, especially since evidence on its implementation and impact on students remains limited. For example, in Australia, sustainability is integrated as a cross-curricular priority, fostering a multidimensional approach that includes social, economic, and environmental dimensions [41].
• In line with this need, studies conducted in Mexico (Flores, 2015) [42] have shown that incorporating the social and economic dimensions into the treatment of sustainability is key to fostering a critical attitude and a deeper understanding of global challenges. In this regard, it is recommended to review the Chilean curricular approach in order to move toward a more integrative perspective—one that addresses sustainability as a multidimensional development model, consistent with the principles of sustainable development and the formative demands of contemporary citizenship.

6. Conclusions

Sustainability is incorporated into the Chilean curriculum and aims to raise awareness of major global challenges. However, greater epistemological depth and semantic clarity are needed to ensure the effective application of this development model in Chilean classrooms. It is also necessary to balance the representation of the environmental, social, and economic dimensions to promote a holistic, collaborative, and critical approach to the principles of sustainability, particularly in the final years of secondary education.

While this study has provided relevant information on the presence of sustainability in the national curriculum, several areas are identified that require further research to complement the findings:

• Classroom-level studies: Evaluate the application of various teaching strategies by educators, such as PBL, interdisciplinary approaches, critical and systems thinking, or other active methodologies in classroom settings.
• Teacher training: Expand research to other educational levels, such as higher education, to understand how sustainability is addressed in the training of future teachers.
• Comparative studies: Compare how sustainability is addressed in the curricula of different countries to identify successful practices that can be adapted to local contexts.
• Impact of sustainability: Investigate how the community perceive and value topics related to sustainable development.
• Analysis of other curricular documents: Include other curriculum documents, such as study plans and programs.
• Experts’ perspectives and analysis: Consider the views of specialists from the Ministry of Education, Ministry of the Environment, or Ministry of Justice regarding the definition and development of sustainability concepts.
• Implementation: Study the impact of sustainability policy in educational institutions and in relation to certification processes.