Pre-Service Early Childhood Teachers’ Perceptions of Critical Thinking and Sustainability: A Comparative Study Between Spain and Poland

Abstract

This study explores the perceptions of future educators, specifically Early Childhood Education students at the Universities of Cádiz and Gdansk, regarding the interconnections between critical thinking and sustainability. The work aims to provide valuable insights into general teacher training, examining how these students’ experiences are contextualized within their respective educational systems and cultural contexts. To achieve this, eleven group interviews (three in Cádiz, eight in Gdansk) were conducted using a structured and expert-validated script. The transcribed data were qualitatively analyzed using QDA MINER v.6 software. Key findings reveal divergent perceptions of critical thinking among pre-service teachers: while Spanish students leaned towards a subjective understanding, Polish students emphasized an objective, data-driven approach. This distinction has significant implications for the conceptualization and teaching of critical thinking in educator training. Despite these differences, both groups of participants highlighted the necessity of implementing active methodologies in higher education (such as cooperative learning, problem-solving, and debates) to foster critical thinking, both for their own development and for preparing for their future practice with young children. This study also identified an excessive emphasis on theoretical aspects of sustainability in these future teachers’ training and a limited understanding of their practical application in the classroom. Furthermore, explicit connections between critical thinking and sustainability were scarce in student responses, highlighting a gap in current educator training in these areas. Collectively, the results suggest significant weaknesses in current teacher training efforts regarding the development of critical thinking and its effective integration with sustainability competencies.

1. Introduction

Anthropogenic challenges remain a priority issue today. These challenges correspond to socio-environmental problems such as climate change, desertification, poverty, pandemics, and war—all characterized by a high degree of complexity and urgency [1]. In 2015, through the 2030 Agenda, UNESCO established 17 key challenges, known as the Sustainable Development Goals (SDGs), along with 169 specific targets addressing various current and future socio-environmental problems. The 2019 UN report on the progress of these goals highlighted significant advances in SDG 3—Good Health and Well-being, SDG 7—Affordable and Clean Energy, and SDG 8—Decent Work and Economic Growth. However, inequalities (SDG 10) continue to deepen, and hunger statistics (SDG 2) are becoming increasingly alarming. The most concerning outcome pertains to SDG 16—Peace, Justice, and Strong Institutions, where no significant progress has been recorded in recent years.

In this situation, there is an urgent need to educate a conscious and engaged society capable of making responsible decisions for a sustainable future, where the integration of ecological, economic, and social aspects plays a key role. This represents a significant challenge for critical pedagogy and other alternative movements opposing contemporary neoliberal capitalism.

In the 1970s, society was dominated by an industrial model in which everyone followed a predefined pattern. During this period, obedience and technical skills were of great importance. Many tasks were routine, with managerial staff overseeing workers engaged in mass production. At that time, the most crucial skills included mastering a profession, adhering to rules and hierarchy, and achieving professionalism, which was reflected in efficiency, consistency, and a sense of equality [2].

Today, we live in an information society where data flows rapidly and in large volumes. Human interactions are facilitated, and most routine tasks are performed by machines. While the ability to carry out routine skills remains important, it is no longer the foundation of excellence. In recent years, there has been an increasing need to develop cognitive competencies that were previously given less consideration. Nowadays, there is a demand for individuals known as transformative intellectuals [3], who possess the ability to critically assess social mechanisms, think independently, engage in self-education, and take corrective actions both in their own environment and within the broader community.

Implementing the principles of sustainable development in practice requires advanced cognitive competencies, particularly critical thinking skills. These skills enable individuals to analyze problems, assess available information, and make decisions based on rational premises. Developing critical thinking allows people to adapt to the changing world. A lack of critical thinking skills can lead to unreflective acceptance of information and irresponsible decisions, with far-reaching consequences for society and the environment. In contemporary society, individuals are constantly faced with a rapid and voluminous flow of information, necessitating the ability to engage in reasoning while simultaneously questioning the credibility of available data and fostering creativity. To navigate this complex landscape and generate solutions to new problems, individuals need to effectively identify and filter relevant data. Critical thinking enables problem-solving by utilizing available knowledge, data, facts, and logic, encompassing both inductive and deductive reasoning, as well as the formulation of appropriate analyses, conclusions, and evaluations [4].

Halpern defines critical thinking as the use of cognitive abilities or strategies that increase the likelihood of achieving a desired outcome, encompassing a full range of mental processes, strategies, and representations for solving problems, making decisions, and learning new concepts. These processes include curiosity, openness, flexibility in considering diverse opinions, and the proactive pursuit of critical thought [5]. Specifically, Halpern identifies four essential skills fundamental to critical thinking that are crucial for future Early Childhood Education teachers as they prepare to address socio-environmental challenges and foster sustainable development:

• Observation: This involves the meticulous process of gathering and analyzing arguments, evidence, and beliefs to discern differences and similarities between facts. For future educators, this means keenly observing socio-environmental issues and recognizing their underlying complexities.
• Identification: This skill focuses on generating conclusions from verified elements and establishing causal relationships between arguments. It requires creating logical connections between observations and prior knowledge, enabling teachers to identify the root causes of problems and their implications for sustainable practices.
• Relevance: The ability to assess the weight of arguments based on criteria such as truthfulness, usefulness, and potential positive or negative consequences is paramount. This allows for the objective analysis of parameters and their significance within a given context, helping future teachers evaluate the impact of their decisions on both children’s development and broader sustainability goals.
• Decision-making ability: This capacity involves determining the most appropriate response to a given problem. It is a synthesis that leads to the most logical conclusion, drawing upon observation, verification, and analysis [5]. For educators, this means making informed, rational decisions that promote both immediate learning outcomes and long-term sustainable behaviors.

By cultivating these critical thinking skills, future teachers will be better equipped to analyze complex socio-environmental problems, rigorously assess available information, and make responsible, rational decisions that contribute to a sustainable future, aligning their professional practice with global challenges and the well-being of future generations.

In the context of critical thinking skills, it is essential to emphasize the role of ethics and relative awareness, which seem to be fundamental to the concept of relevance. This is because pure logic can, in the long run, produce effects opposite to those intended. In human judgment, logic may contradict common sense, leading to decisions that are harmful to people and the environment. Some choices may be justified from the perspective of short-term benefits while simultaneously conflicting with human conscience, ethics, and common sense. Critical thinking, therefore, is not merely a cold, logical reasoning skill; it also incorporates social codes, informal parameters, and sensitivity to context and culture [2]. Developing this ability requires a lifelong learning approach, where education begins with family upbringing and continues through both formal and informal educational systems. Therefore, the global concept of sustainable development should be integrated into the formal education system. Despite worldwide efforts and numerous initiatives undertaken within higher education, incorporating sustainability education into curricula remains necessary [6]. However, this is not an easy task, as it requires profound changes across various educational programs at different levels.

Thomas [6] emphasizes the need for a shift toward transformative education, based on learning strategies that develop students’ ability to improvise and adapt, innovation and creativity, but most importantly, they focus on developing critical thinking. Heinrich et al. [7] argue that contemporary complex social problems require both critical thinking and engaged citizenship. Ilbay Guaña and Espinosa Cevallos [8] highlight the interconnections between critical thinking, creativity, and problem-solving skills, which prepare students to understand the world, make informed decisions, and act for society in the face of 21st-century challenges. However, these competencies should be cultivated not only among students but also among educators.

Educational programs are responsible for fostering the formation of a democratic public sphere where diverse and marginalized voices can be heard. They should not merely cater to academic disciplines that train specialists disconnected from the challenges of communal life [9]. Universities should not allow their mission and activities to be reduced to the interpretation of prescribed dogmas, nor should knowledge become merely a product that supplies qualifications for the “free” labor market Giroux and Witkowski (pp. 76–77) [10]. According to critical pedagogy, universities should serve as agencies of democratic discourse rather than passive mechanisms reproducing conditions that reinforce the class power of current financial and political elites [11]. For this reason, critical education extends beyond the vision of the university as a mere training ground for future workers (Giroux and Murchland pp. 82–83) [12]. Instead, it should empower individuals to transition from being objects of history to becoming its subjects—capable of shaping their surrounding reality independently.

Addressing significant social issues must occur not only at universities but also at all levels of formal education, starting from early childhood institutions. This ensures that individuals will not easily succumb to the indoctrination of dominant ideologies but rather engage in critical reflection on the kind of society we want to live in [13]. Will we continue to focus on bureaucratic capitalism, whose economic paradigm leads to growing social inequalities, the depletion of our planet’s natural resources, and increasing pollution [14].

Colás-Bravo et al. [15] emphasize that content related to Education for Sustainable Development (ESD) should be incorporated into both initial teacher training and continuing education. Raising awareness of sustainable development is crucial for cultivating so-called sustainability competencies.

In the European Sustainability Competence Framework [16]—identified as a policy action under the European Green Deal—12 sustainability competencies were outlined. These competencies are interconnected and aim to enable learners to take action or advocate for action in protecting ecosystems, promoting social justice, and envisioning a sustainable future. In this context, UNESCO defines five key competencies for sustainable development:

• Systems thinking competency.
• Anticipatory competency.
• Normative competency.
• Strategic competency.
• Interpersonal competency.

These competencies encompass cognitive, affective, volitional, and motivational elements, and their acquisition occurs through action, experience, and reflection [1].

In Spain, CRUE, as the main body representing universities before the central government, approved in 2005 (and reaffirmed in 2011) guidelines for integrating sustainability-related competencies into all study programs. Four key competencies for sustainable development were defined, which should be included in academic education:

• SOS1. The ability to critically contextualize knowledge by linking it to social, economic, and environmental issues—both locally and globally.
• SOS2. The ability to use resources sustainably and prevent negative impacts on the natural and social environment.
• SOS3. The ability to participate in social processes for sustainable development.
• SOS4. The ability to apply ethical principles and values in professional and social practice.

For example, the University of Cádiz (Spain) implements these competencies in its educational programs through its third Strategic Plan of the University of Cádiz [17].

In Poland, the priority is to educate future teachers with a focus on developing critical thinking and sustainability competencies—two key pillars for building a more just and equitable world [6,7,8,9,10,11,12,13,14,15,16,17,18,19]. Poland has a branch of PRME (Principles for Responsible Management Education), a global forum for responsible management education, initiated by leading business schools. The main goal of the Polish PRME branch is to promote the need for students and the academic community to think and act in terms of the common good, particularly concerning environmental protection and sustainability. Members of PRME encourage universities to support initiatives in corporate social responsibility and integrate sustainability topics into curricula and academic projects [20].

Many Polish universities undertake independent initiatives to promote the Agenda 2030 goals for sustainable development, developing their own strategies and organizing events to foster sustainability. The University of Gdansk is actively engaged in promoting and implementing sustainable development principles through various initiatives and activities.

The mission of the University of Gdansk includes shaping a knowledge-based economy and society. To further its sustainability efforts, the University of Gdansk established the Center for Sustainable Development, which serves as a university-wide unit responsible for promoting the university’s scientific potential and fostering pro-environmental attitudes within the academic community.

Additionally, the university has published a sustainability strategy encompassing actions at global, regional, and local levels. Through various initiatives, the University of Gdánsk aims to integrate sustainable development principles into education, scientific research, and daily university operations, contributing to raising ecological and social awareness among students and the local community. The university actively engages in the implementation of the Sustainable Development Goals (SDGs), promoting knowledge-sharing, practical education, and the development of skills that empower individuals to make informed decisions with future generations in mind [21].

2. Objectives

The primary objective of this study is to analyze and compare the perceptions of future Early Childhood Education teachers in Spain and Poland regarding the development of critical thinking competencies for sustainability (Objective 1). Furthermore, it aims to identify the challenges they face in their university training for the acquisition of these specific competencies (Objective 2) and to gather their suggestions for improving teacher education in critical thinking oriented towards sustainability (Objective 3). And finally, to explore how they perceive the relationship between critical thinking and sustainability competencies within the academic context (Objective 4).

Based on the objectives of this study, the following set of research questions was formulated to establish the theoretical framework of the project:

• How do future early childhood education teachers understand the concept of critical thinking?
• In what ways do future teachers encounter the topic of sustainable development during their academic coursework?
• Which forms of academic activities at the university support the development of critical reflection on the future consequences of human actions?
• What difficulties do students face in developing critical thinking in the context of sustainability-oriented actions in higher education?
• What actions could universities take to better support the development of critical thinking among future teachers?
• How do future teachers plan to integrate critical thinking into their future teaching practice?

3. Methods

This research is framed within the qualitative and interpretative paradigm, given its aim to explore and understand how participating students perceive the relationship between the development of critical thinking and competences for sustainability based on their experiences in a specific, namely academic, context [22]. According to Thanh and Thanh [23], the combination of the interpretative approach with qualitative methods provides a methodological framework and a means to collect data, respectively, with validity in the field of education.

3.1. Context and Participants

This research was conducted in the context of initial teacher training during the first semester of the 2024/25 academic year, specifically in the Bachelor’s Degree in Early Childhood Education at the University of Cádiz (Spain) and in the Integrated Master’s Degree in Early Childhood Education at the University of Gdansk (Poland).

A total of 55 students aged between 19 and 27 (38 women and 17 men) participated, all of whom were taking the subject of Didactics of the Natural Environment in the third year of the Bachelor’s Degree in Early Childhood Education at the University of Cádiz. And 41 women aged between 21 and 23 years who were taking the subject “Pedagogy of Early Childhood” in the third-year of the Integrated Master’s Degree Programme in Early Childhood Education at the University of Gdansk.

3.2. Data Collection

The information was collected using the focus group technique, on account of its potential to delve into the meanings, perceptions, ideas, and experiences of the participants during their university years [24]. The aim was to understand the phenomenon from the perspective of those involved [25]. Unlike a colloquial conversation, focus groups concentrate on planned themes, through a structured or semi-structured conversation, moderated by a researcher, with a small group of participants [26]. The focus group, as a validated technique, allows the perspective of the protagonists to be obtained, contrasting opinions spontaneously. It is framed within group interviews and seeks to understand the phenomenon from the perspective of those involved [27].

In this study, 11 focus groups meetings were conducted: 3 at the University of Cádiz (G1, G2, and G3) and 8 at the University of Gdansk (G4 to G11). Each group consisted of five to six students. Selection was purposive and voluntary in both universities, seeking the participation especially of men, given the female majority in the degree. Information about this study was provided to students by the course teachers orally during class sessions. Students who were interested in participating could express their willingness by contacting the researcher directly. The inclusion criteria were: enrolment in early childhood education studies and provision of informed and voluntary consent to participate in this study.

All participants involved in this study provided their informed consent prior to participation. They were fully informed about the objectives of the research, the voluntary nature of their participation, the confidentiality of their responses, and the intended use of the data.

Each group was accompanied by a researcher as moderator (second and third author in Gdansk and Cádiz, respectively) in a familiar environment (the university). The sessions were audio-recorded, with prior express consent, for subsequent transcription and thematic analysis.

The interview script was structured around six questions and validated by experts: two Spanish academics, both with doctorates in the area of didactics of experimental sciences, and four Polish academics, of whom two are professors and two have doctorates. One of them is a professor in the field of early childhood education didactics, two are doctors in the field of early childhood education, and one is a professor in the field of social pedagogy.

Each expert was provided with a table where each of the six questions appeared in the first column. The second column described the intention of the question. In the third column, they were asked to rate the “relevance” of the question from 1 to 3, where 1 = Inappropriate; 2 = Average adequacy; and 3 = Adequate. In the fourth column, they had to rate the “Clarity” from 1 to 3, where 1 = Confusing; 2 = Could be improved; and 3 = Clear. The last column provided the possibility of suggesting alternative wording for each question if necessary. At the end of the table, a complementary space was added for the experts to include other possible questions, indicating their wording and purpose.

To obtain a numerical value of the degree of agreement for each question, the variance of the judges’ ratings for each of these was used. A variance of 0 would indicate perfect agreement, and higher values would indicate less agreement among the judges for that question. Regarding the relevance of the questions, the judges showed perfect agreement in questions p1, p5, and p6. There was a high degree of agreement in questions p2 and p4, with only a slight discrepancy from one judge. Question p3 showed the greatest variability in the judges’ ratings, indicating a lower degree of agreement. As for clarity, the variances obtained from the judges’ ratings were relatively low, indicating a moderate to high level of agreement in the clarity of each question individually. Question p4 showed the highest variance, indicating the least agreement in its clarity. According to the results obtained and comments collected by the experts, some modifications were made to improve the wording of all the questions, resulting in the final script used for the focus group interviews.

The six questions were formulated to investigate the following key aspects: three were specifically designed to explore participants’ perceptions of critical thinking, sustainability, their interrelationship, and challenges and suggestions for how these things should be trained. Objective 1—to analyze and compare the perceptions of future Early Childhood Education teachers:

◦ Question 1: What is critical thinking for you? (Q1) was designed to capture participants’ initial definition and understanding of critical thinking.

◦ Question 2: Have you encountered the concept of sustainability in your classes? To what extent can you relate this concept to critical thinking? (Q2) directly sought their perceptions of sustainability and, crucially, their ability to establish a connection with critical thinking.

Objective 4: Explore how they perceive the relationship between critical thinking and sustainability competencies within the academic context.

◦ Question 2: Have you encountered the concept of sustainability in your classes? To what extent can you relate this concept to critical thinking? (Q2) is fundamental, as it directly addresses the perceived relationship between both concepts in their training.

◦ Question 3: Considering the class activities of the subjects you have taken so far, which ones have helped you to reflect critically on the future consequences of our actions? (Q3) was formulated to identify how academic experiences foster critical reflection with an orientation towards long-term implications, which inherently relates to sustainability.

◦ Question 4: What kind of difficulties do you think prevent you from developing critical thinking that would allow you to act in a more sustainable framework in Higher Education? (Q4) explicitly links difficulties in developing critical thinking with its application in a sustainability context within higher education. Objective 2—to identify the challenges students face during their university training.

◦ Question 4: What kind of difficulties do you think prevent you from developing critical thinking that would allow you to act in a more sustainable framework in Higher Education? (Q4) is directly aimed at identifying the obstacles perceived by students in their training process concerning these competencies.

Objective 3—to gather their suggestions regarding that training:

◦ Question 5: What do you think universities could do to better prepare students to think critically? (Q5) was designed to elicit direct recommendations from participants for improving university training in critical thinking.

◦ Question 6: As future teachers, can you think of any way to incorporate critical thinking into your teaching? (Q6) While focusing on their future practice, students’ responses indirectly reflect the needs and suggestions for their own training, indicating what they consider relevant to apply in the classroom, and thus, what they would have expected to learn or how their training could have better prepared them.

The validation by six experts from different fields ensured that each question was relevant and clear, guaranteeing that the script would be an effective tool for collecting the necessary perceptions to address the research objectives.

3.3. Data Analysis

Firstly, the recordings of each of the focus group sessions were transcribed. The transcriptions were analyzed using QDA Miner v.6 software. The data analysis was carried out through an emergent thematic coding process [28]. This approach allowed themes and patterns to emerge directly from the data, without imposing predefined categories. The rigorous process of emergent thematic coding involved the following specific steps to organize and interpret the rich qualitative data collected:

• Familiarization: An exhaustive reading and re-reading of all focus group interview transcripts was conducted in order to allow thorough immersion in the data. This initial phase aimed to grasp the nuances, tone, and context of participants’ responses, and to identify preliminary ideas relevant to this study’s objectives.
• Generation of Initial Codes: In this stage, relevant text segments were systematically labeled with descriptive codes. These codes were generated directly from the content of the transcripts, categorizing information provided by participants in relation to each question posed in the interview script (Q1 to Q6, as detailed in

  Table 1. Interview questions and emergent thematic coding process.

  Questions	Coding
  Q1. What is critical thinking for you?	Attitude Procedure Content
  Q2. Have you encountered the concept of sustainability in your classes? To what extent can you relate this concept to critical thinking?	Integrated child development Sustainable Development Goal Absence of relationship
  Q3. Considering the class activities of the subjects you have taken so far, which ones have helped you to reflect critically on the future consequences of our actions?	Child development Classroom methodology Design of activities
  Q4. What kind of difficulties do you think prevent you from developing critical thinking that would allow you to act in a more sustainable framework in Higher Education?	Traditional teaching method Curriculum sequence Adaptation to the learner
  Q5. What do you think universities could do to better prepare students to think critically?	University teacher training External agents Training in practice Listening to the student Teaching coordination Using active methodologies
  Q6. As future teachers, can you think of any way to incorporate critical thinking into your teaching?	Teaching based on real situations Creating situations for participation Generating an authentic relationship

  ). For instance, for Question 1, initial codes such as “Attitude”, “Procedure”, and “Content” were identified based on the participants’ expressions.
• Searching for Themes: Following the initial coding, similar or related codes were grouped into broader, more significant themes. This step involved identifying underlying patterns and connections that transcended individual codes, reflecting recurring perceptions or ideas expressed by the participants.
• Review and Refinement: The process of creating codes and themes was iterative. Themes and codes were continuously reviewed and refined as the data was explored in greater depth, ensuring their internal consistency and pertinence to the main objective of this study. This involved adjusting code definitions, merging codes that were too similar, or splitting them if they encompassed too many distinct ideas.
• Defining Themes: Finally, each emergent theme and its constituent codes were clearly and concisely defined. This phase ensured that each theme represented a distinct facet of the participants’ perceptions. The codes defined for each question of the interview script are further detailed in Table 1.

4. Results

4.1. Question 1. What Is Critical Thinking for You?

Regarding question 1, three codes were defined corresponding to three key terms: Attitude, Procedure, and Content. The “Attitude” code encompasses text fragments that reflect the interviewees’ stance towards new information they received.

G4: “…critical thinking consists of not automatically believing everything we hear”.

G7: “…The ability to see a situation or problem from different perspectives, to think objectively, to analyze the situation, and to think holistically”.

G11: “…Questioning what is received”.

It can be observed that the conveyed idea is that having a critical thinking approach implies adopting a position of constant questioning of received information. This attitude is similar to that found in scientific fields, where knowledge is not immutable and is subject to continuous questioning based on new data or facts that may emerge. However, this perspective was not the only one present in the interviews, and differentiates the data collected from the Polish discussion groups (attitude already noted) from the interviews with students from Spain. In the Spanish interviews, attitudes reflecting a significant subjective component were also identified. Indeed, this component appears to characterize critical thinking. Intersubjectivity, in this context, is the acknowledgment that individual critical thinking exists, but is not necessarily bound by objective facts or subjective reality. Instead, it is subject to the “individual truth” that prevails alongside “other individual truths,” and the stance towards this is one of respect for others, rather than questioning the facts upon which that knowledge may be based. These ideas are captured in the following excerpts:

G2: “And you always have to respect other people’s criticisms. Because I might not think the same as A or B, but I have my critical thinking”.

G3: “You also have to be open, to listen to other people’s opinions”.

Respect for others takes precedence over objectivity. Opinion is a defining element of critical thinking. This particular approach is noteworthy as it implies the virtual impossibility of constructing an objective reality, even one mutable over time with the contribution of new objective data. This should prompt reflection on the type of training offered to students and the risk involved in accepting individual viewpoints based on “respect” for others as a principle superior to objectivity.

The “Procedure” code includes statements referring to the concept of critical thinking in relation to the process followed by participants when presented with new information. The dominant opinion in the interviews refers to the “analysis” of information and to facts as necessary references to reinforce an objective perspective.

G7: “To analyze the situation, that is, critical thinking is that we analyze the situation”.

G10: “It is a process of analyzing the consequences and actions taken for the current situation. The analysis is based on facts, not on unverified information”.

G11: “Even in scientific research, it is worth checking if there is other contradictory, additional information or anything else”.

It can be observed that the statements from the Polish student discussion groups revolve around preserving objectivity through the search for diverse, reliable, fact-based sources, and that comparative analysis is used as an appropriate way to ensure a result as close as possible to reality. However, statements that emphasize subjectivity are also detected, as shown below.

G2: “how to construct your own thinking based on your opinion and also a bit on experience”.

G3: “…that we have to base ourselves first, inform ourselves, and then what you think is from your point of view and your criteria”.

This shift towards the individual as the ultimate reference of reality indicates the limited consistency and validity that some students attribute to reality constructed intersubjectively and from facts.

Regarding the “Content” code, ideas referring to the product generated when using critical thinking have been grouped together. In this way, three significant contributions were found. The first relates to knowledge as something that can be objectively demonstrated independently of the subject who thinks critically, and that it is a slow, gradual process.

G5: “critical thinking is mainly about the search for knowledge, which is also related to patience, because that knowledge does not come immediately”.

The second contribution sets ethical or moral questions aside from critical thinking. Thus, good or evil are outside the sphere of influence of critical thinking.

G5: “I would not consider critical thinking in terms of positive and negative things. The fact that there are different perspectives on a phenomenon does not mean that one of them is good or bad”.

The third contribution questions the possibility of constructing a truth, a reliable knowledge among people. Knowledge, although mutable as it is in science, is based on facts and data. This element is not considered important by some participants, since the “absolute truth” does not exist. Consequently, the possibility of objective knowledge, of knowledge shared intersubjectively using an accepted method, such as the scientific method in the field of science, is questioned.

G2: “I think it’s more subjective, right? Because the thing about critical thinking is that everyone has their own point of view, so to speak, because there is no absolute truth”.

Again, this association with the subjective is found in the interviews with the Spanish students.

4.2. Question 2. Have You Encountered the Concept of Sustainability in Your Classes? To What Extent Can You Relate This Concept to Critical Thinking?

Across all the interviews, three basic ideas emerged, captured in the following codes: (a) integral development of children, (b) the Sustainable Development Goals (SDGs), and (c) the absence of a relationship between critical thinking and sustainability. The first idea, predominantly expressed by the Polish participants, relates sustainability or sustainable development to the “integral development” of children. That is, the specificity of the early childhood education degree addresses the development of children from different perspectives (psychological, motor, social, and cognitive). Sustainability and sustainable development are identified with the future professional capacity to approach the education of children from a “holistic” perspective.

G7: “We came across this in Developmental Psychology, I think. … to see the development (of the child) as a whole, not to see it in a stereotypical way. In a holistic way”.

G4: “I think we have all heard about sustainable development, although perhaps it has not been addressed exactly with those words. However, we have dealt with related topics, such as the importance of the multidimensionality of development”.

G5: “Honestly, I have only heard about sustainable development in relation to children, that is, that children need sustainable development. And I associate it with that, not as something that affects us directly”.

G11: “Yes, but more in relation to children, not so much with us, adults; it was mainly about all aspects developing properly (physical, psychological, emotional development, etc.)”.

The second major idea, which emerged among the Spanish students, acknowledges that the SDGs have been addressed in class, but some interviewees associate this with the theory–practice dichotomy in their training process as future teachers. In other words, it has generated a feeling of frustration for them because they are unable to apply this knowledge to a real-world situation.

G2: “Yes, especially when we talked about SDGs”.

G1: “…in the end, you must have a foundation of sustainability to be able to develop other ideas from that. What happens is that in the faculty we have all been super theoretical, we have learned a lot about the issue of the SDGs, for example, but we have not yet been able to apply it to a practical setting. We are given the option to create activities, to create situations in classes, to do various things, but it’s nothing that I am currently capable of taking to the practical field in an early childhood class”.

However, the practical activities carried out in the university classroom are not always rejected by the Spanish interviewees as being limited in their contributions to professional training. Their contributions and influence on the change produced in students’ initial ideas when starting the degree are recognized.

G3: “I think that yes, that throughout the degree, as Ana said, we have done many practical exercises that have to do with sustainability and critical thinking. The thing is, in the end, we have some ideas at the beginning that thanks to the practice we are doing… (the silence suggests that learning takes place, moderator’s comment)”.

The third idea refers to the limited explicit reference that participants from both universities make to the concept of sustainability and its relationship with critical thinking.

G6: “We have not encountered that, or if it was mentioned, it was superficially, so we really don’t remember anything about that. That is, it wasn’t something typical like this is sustainable development”.

4.3. Question 3. Considering the Class Activities of the Subjects You Have Taken So Far, Which Ones Have Helped You to Reflect Critically on the Future Consequences of Our Actions?

In the participants’ responses to this question, three emergent thematic codes were identified. The first of these (Child development) refers to the identification made by some students regarding the future consequences of their actions on the development of the child. That is, they make a future projection as a teacher on the effect of future professional actions on the infants in their care, rather than reflecting on their own learning. In this regard, no differences were found between the participants from both countries.

G1: “I think that above all those that are more related to psychology, because by providing all the foundations about how the child’s development goes, it is possible to change some behaviors, some way of thinking regarding their treatment, to avoid future consequences in children”.

G5: “And we also had classes with Dr. M., it was in physical education, and now in support of the child’s development and autonomy”.

G6: “Each of these subjects taught us an open attitude towards mistakes, to tolerate mistakes, without rejecting the student for that, for example. That is, did they tolerate the students’ mistakes? Or their own? Actually, everyone’s”.

G11: “The classes with Dr. M., which dealt a lot with the consequences of how we relate to children (knowledge about physical education, support for the child’s development and autonomy)”.

The second code has been called “Classroom methodology”. This code has been defined as “Methodological strategies or activities that are used in the classrooms to favor critical thinking and help reflection,” grouping in it those verbalizations related to the dynamics identified in the university classroom which are useful for addressing this competence. Again, the contributions of the students from both countries coincide.

G2: “At the end of doing a job, for example, of presenting a topic, sharing a debate, that everyone gives their opinion, that everyone can debate and say what everyone thinks”.

G2: “The subject of Foundation also made me think a lot. When he showed us a video of a little girl. To me, the thought of how those children can become like that because of things they have experienced. I mean, those things make me think a lot”.

G4: “In classes like environmental education, we learned about innovative approaches to teaching, including practical activities such as experiments and field trips, in addition to reflecting on educational paradigms”.

G5: “Everything was introduced with examples, which made it easier to understand. And I think that, therefore, that knowledge from the conferences will stay with us when we finish our studies”.

G8: “Practical examples are also important, sharing knowledge from real experience or giving guidelines on how to work with children, which prove to be effective in practice”.

G9: “The stories and professional experiences of the teachers have also been very useful, the practical information ‘taken from real life’ that helps to become familiar with the reality of the future profession”.

G11: “We delved into the meanings of different words and, thanks to this, we were able to better understand what we were talking about. We were able to see what the consequences of specific options would be”.

Analysis of the extracted text fragments allows us to conclude that the variety of didactic strategies and activities used in the university classroom helps us to think critically about the future consequences of our actions. That is, beyond the master class describing theories, information, or data, the description of life experiences (first-person storytelling), the use of illustrative examples, case studies using audiovisual media, debate or discussion groups, or the establishment of differences and similarities between concepts, ideas, or theories, all stand out. In short, those strategies that help students to face the learning situation in an active way, which force them to take a position, to argue, or to elaborate their own discourse, are highlighted as valuable methodologies for the development of critical thinking and training in sustainability.

The third emergent code refers to the “Design of activities.” In this code, statements that appeared in one of the group interviews have been collected. It is interesting to highlight this contribution, despite it appearing in only one focus group of Spanish students. They express the importance of designing learning situations while thinking about the future of early childhood students, and that implies, for them, using critical thinking.

G3: “…the learning situations that we do here, for me, is something that is going to help me fundamentally in the future because they are activities that you are proposing, that you would develop when you are a teacher in the future”.

G3: “…to investigate, to elaborate, to put yourself in the place of a teacher”.

G3: “…what we are doing is designing activities, learning situations and training ourselves. Because we are training ourselves on a lot of different elements, all that has to be based on a source and then elaborate our critical thinking that we are going to take to the classroom”.

4.4. Question 4: What Types of Difficulties Do You Believe Hinder the Development of Critical Thinking Skills Necessary for Engaging with Sustainability Within Higher Education?

Question four aims to have students identify the obstacles preventing the development of critical thinking for action within a more sustainable framework. In this case, three codes have been identified, highlighting, as will be seen in the analysis of this question, the absence in their statements of a connection between critical thinking and sustainability. The interventions have primarily focused on the difficulties in developing critical thinking at the university level.

Regarding the first code (Traditional Teaching Methods), this was used to group statements related to the lecture format and assessment through exams to verify content mastery. This implies a unidirectional teaching methodology, without offering genuine opportunities for interaction with and among students. Interviewees made numerous verbalizations in this regard.

G1: “…that we focus so much on theory, theory, theory, and in the end, we are a bit like mechanics, high school. You teach it to me, I have to learn it by force because you are going to ask me, but then it’s true that I don’t really learn what you are teaching me. You are telling me you are giving me this because it will be on the exam, so I will study it out of obligation”.

G2: “They give you the topics, and you have to study and regurgitate (in the exam). And I’m not understanding anything”.

Even in practical activities, they consider overly strict guidelines to be a significant impediment to developing critical thinking within the framework of sustainability in HE.

G3: “From my point of view, I believe that some impediments we have are that everything is very mechanized in the sense that we have to elaborate practical assignments based on a structured index, based on structured instructions, and in the end, we are like computers doing the work and the practical assignments without having our opinion on what we think about it or, well, what thoughts we have about that concept”.

Or, that the teacher offers a rigid frame of reference that dictates the criteria for positive or negative evaluation.

G4: “We had a class where the professor asked us questions, and when we responded according to our convictions, those answers were somewhat criticized, and we had to adhere to a specific key that she expected. Generally, it was something negative, especially when someone had a different point of view from the professor; so, definitely that”.

They also express that this type of teaching, with an assessment focused on content, leads students to a certain conviction: that it is only necessary to know how to memorize to obtain a university teaching degree.

G5: “That is, it is not necessary to think critically, only to memorize well”.

G6: “That is, you can’t think too much or discuss it, you just focus on memorizing. If it has to be the only correct definition, sometimes even word for word”.

Regarding the second code (Curriculum Sequence), a series of verbalizations related to how the teaching is structured has been grouped together. This is important for the interviewees to the extent that they consider there to be a relationship between what can be learned in a “practical” context (for example, in an early childhood education classroom) and the acquisition of professional competencies. In this sense, changing the organization and sequencing of subjects could provide an added improvement in the capacity for critical thinking. This would allow for the construction of a more sustainable framework, alluding to the theories shared in the university classroom.

G1: “First, that the practicums are not in the third and fourth years (of the degree). That we have, for example, in the first year a few specific hours with the children we are going to have, a minimum of contact to be able to gradually see how they develop, how to interact with them. Over time, what we have learned from different theories, to be able to apply them to our teaching practice”.

Although they may recognize that having clear knowledge is important before approaching teaching practice.

G3: “And many times, perhaps they ask us to elaborate that activity of things for young children about things that perhaps we are not even really trained in yet. That is, for example, if they give me a practical assignment on sustainability, I will first have to acquire that true knowledge so that I can then express it”.

They also point out that one of the difficulties is oriented towards the limited opportunities to be creative, develop one’s own proposals, and be supported by the teaching staff in this development.

G4: “…I believe that we have great potential to create something interesting, a very good project, or simply do something that really contributes. But we don’t know how to do it. We also don’t have much direct support from the professors, who could help us, show initiative or interest in creating something like that”.

Another idea that emerges is the level of difficulty, which does not seem to increase progressively as the courses of the degree are completed. This causes demotivation and low engagement in classes.

G5: “In these classes, sometimes the tasks are so simple that I feel like a child in those classes. I understand that we are going to do similar things with children, and it is probably done from that perspective, but for us it is so trivial that we don’t feel like we are really developing. We create things that we could do in four minutes, and for the professor that’s fine, “Do this, it will be great!’, but for me that’s so easy that I feel like I’m not learning anything”.

Regarding the third code (Adaptation to Students), some verbalizations have been collected that reflect the teaching staff’s lack of awareness of the students’ current stage. In the previous text fragment (from G5), we see how students allude to the low complexity of the activities proposed in the classroom and how far removed they are from the students’ actual capabilities. This implies that the curriculum should be sequenced at the degree level, with an approach that allows for a gradual increase in the complexity of the demands made by the teaching staff. However, in the code that concerns us, the aim was also to capture a difficulty related to the absence of initial assessment mechanisms that would allow the teaching staff to adapt their teaching to the group/class.

G5: “They teach us not to infantilize children, not to make them dumber, to enter their zone of proximal development, not only their current one, and in the end, we ourselves do the same. Perhaps they don’t adjust the methods to our age or level of knowledge. Or maybe they should broaden the tasks, for example, telling us ‘try to do it this way,’ to raise the level and make us think more, so there is more complexity”.

G11: “…they tell us that we must do something in a certain way, but then we are treated differently.”

G5: “So, these classes are supposedly good because they are really enjoyable, but their elements don’t contribute anything to us. Sometimes there are classes where they tell us that children cannot sit in a certain way and have that teacher mentality, but we ourselves have to do it in the classes”.

4.5. Question 5. What Do You Think Universities Could Do to Better Prepare Students to Think Critically?

Question 5 gathers the solutions that students proposed in response to the difficulties they identified in the previous question. These have been grouped into six codes: initial teacher training, external agents, training in practice, listening to the student, teacher coordination, and active methodologies. Again, no significant differences are found between Spanish and Polish students, who raise similar points.

The first category that appears in the verbalizations refers to the need for teachers to be trained. In this case, they allude to the need for teachers to have direct professional experience in the task for which they are training future professionals.

G2: “Another thing, which I also think, is that a large proportion of teachers are specialized in the subject. Those teachers have never taught in an early childhood classroom in their lives. And it’s not that they are isolated cases. Isolated cases are the teachers who come to us and say, ‘but when I was teaching…’ But the rest have never taught. They are telling us how we have to do it and they haven’t done it”.

Furthermore, the teaching staff should use active methodologies in the classroom that encourage reflection and are dynamic.

G3: “…I think that at a higher level like university, we should learn more knowledge and that classes should be more about reflecting and saying, well, why is this? And that, thanks to the fact that we have professors who are trained for that, well, that they can transmit that knowledge to us and that the classes are more dynamic”.

In this sense, it is acknowledged that some of the teaching staff teach, as the content of their subjects, elements that are part of active and reflective teaching. However, they do not put these elements into practice in their own classes. That is, they use the lecture form to explain active and participatory methodologies.

G3: “…I think that many teachers tell us that you have to innovate, you have to do X, and they themselves are teaching us in the traditional way, that is, they read us PowerPoint and that’s it. So, if you really want to teach something, start with yourself and then others will teach it”.

G6: “Better selection of teaching staff. We are referring to classes in the form of a lecture, where only the teacher speaks, always with a boring tone. But there are also isolated cases”.

The code “External agents” refers to the incorporation of professionals external to the university and with direct professional experience who can come to university classrooms to offer their knowledge and perspectives. That is, to provide knowledge from practice. This solution directly points to the lack of professional training of university teaching staff mentioned above, and which respondents would like to make up for with the presence of non-university professionals.

G8: “…we propose that people who are professionally active teach classes of practical knowledge or that we have classes with people who have professional experience”.

They also indicate the desirability of recent graduates from the faculty being able to pass on their professional or job search experience.

G2: “One of the things I would do, to reinforce critical thinking a bit, would be to bring in former university students who are working, who have found a job or who haven’t. Those who have passed the competitive exams, those who found a job straight away, and those who have been taking the exams for five years, don’t get in anywhere, and those who have entered a private school, those who have entered a public school. To bring us people who have been here, who have studied the same as me, and who have already faced what is working life and life as a teacher. Because in the end we don’t have that source of information”.

G4: “Of course, there are many cases and problems in the educational field, but I think there are some that are recurrent. Those about which we really should reflect to find solutions and submit them to analysis with people, as you mentioned, K., competent people who tell us where to go and what would be the best option for each particular case”.

Related to the above, the code “Training in practice” refers to the need felt by students to have direct pre-professional experiences or, at least, to study practical cases.

G4: “In the sense that we have internships that provide experience and allow us to form our own opinion about what the practical world of teaching is like in different institutions, but there are very few. And, actually… besides, they come a little late”.

G1: “…we used to go to the youth center here in Puerto Real and we would make an appointment to reserve the place to do the workshops and the truth is that it was very cool because we worked with the children, they were of different ages”.

G7: “Yes, I think that practical examples, simply practical tasks and practical examples help us a lot in critical thinking, because it is in practice where we can best see those relationships”.

Under the code “Listening to the student”, text fragments have been grouped that allude to the need for students to express themselves, either to the teacher or in small groups of students that allow them to share ideas and experiences.

G4: “I think that a good space to develop this thinking would be more practical forms of work, in smaller groups, where we can express ourselves and where contact with the teacher is more accessible. Because in a lecture in a large auditorium, there are really fewer opportunities to express our opinion”.

G3: “I think they should be more flexible when it comes to handing in a paper, as A. said before, that it shouldn’t be all so structured and that we can have a little voice”.

G5: “We can’t discuss among ourselves and ask each other ‘And what do you think?”. or ‘What if we do this differently?’, and rather we listen to each other, but there is no exchange of ideas. And I think that what could help us the most in the development of critical thinking would be to be able to discuss more among ourselves. Because that way we would have the perspective of the other person and we would think: ‘Ah, maybe I could think about that, maybe I could take something different from this idea’, and really… It would be great if we had group work for that… But, of course, what we need is discussion, to talk”.

G8: “We want to express our opinion at the university and think reflectively”.

The following code (teacher coordination) reflects the concern of students regarding subjects that repeat content and that do not represent a significant advance in their training.

G3: “Sometimes they are teaching us the same things for four years”.

G5: “Perhaps all classes in general are very similar to each other. Group work, group tasks… We talk about the same topics. Yes, the topics are repeated a lot every year, the same topics for our discussions, which we no longer want to discuss for the third or fourth time, because we have already talked about that so many times that, well, we don’t really talk about the topic, but we talk about our personal things, and then we know what to say when we are in the forum, so there is also a lack of diversity and novelty”.

Finally, the code “Using active methodologies in class” collects the verbalizations that students have made about how active methodologies help to develop critical thinking. By way of illustration, the following have been selected:

G7: “It was difficult, but… We collected materials from each exercise we worked on, some worksheets on the pedagogical paradigms. And at the end of the semester we had to put all that together in a portfolio, put our notes, our reflections on all that, and some observations. The idea was to see how our way of thinking changed during the classes, during the whole semester, and to see that same topic, how we saw it at the beginning of the classes and how we see it now. And how do we see it now, when we write this portfolio? I personally changed a lot. So, we could simply illustrate how our way of thinking changed”.

G9: “The most motivating tool so far in the classes has been the Oxford debate, in which students were offered a space for a safe and stimulating discussion, without the risk of the conversation being suddenly interrupted”.

G7: “Writing all that was very stimulating for critical thinking, because we had to face the fact that maybe we weren’t thinking correctly at the beginning, that our opinion changed”.

4.6. Question 6. As Future Teachers, Can You Think of Any Way to Incorporate Critical Thinking into Your Teaching?

Until now, students have expressed their opinions about critical thinking and its development at the university where they study. This new question aims to explore whether they have considered developing critical thinking in their future teaching practice and how they would do it. The responses collected from both groups of participants (Polish and Spanish) are largely similar to what they have demanded for themselves from the university itself. Two thematic analysis codes have been identified: teaching based on real situations, and creating situations for participation. Regarding the code “Teaching based on real situations,” it is observed that the response focuses on generating situations of cognitive conflict or posing problems.

G4: “Well, I think that, for example, through problem-based tasks, something we learn in our classes”.

G1: “…to give the children a conflict that they themselves work on that conflict, that they discover (by themselves). Because in the end, that is always something that the professors here at the faculty tell us a lot. We give the child the problem, it is the child who intervenes and we are the ones who act as guides. We don’t give the children the answer, but it is the child who seeks that answer”.

Offering opportunities for experimentation and error as mechanisms to learn without the fear of being wrong.

G3: “…I think that experimentation is important. That the children see what we are doing, that they propose their hypothesis of what they think may happen or what it may be used for, or in whatever context, and that they see what happens. Without being afraid to speak in case it is not like that”.

Or recreating real situations in the school that serve as a resource for accompaniment in learning.

G2: “Or maybe doing, for example, activities that are to teach a concept. That everything is very practical, you know? I don’t know. For example, to learn about plants, that the children have a garden, you know?”.

In the code “Creating situations for participation,” those verbalizations that reflect the importance of children expressing themselves freely have been collected. The activities revolve around the need to listen to children and for them to listen to each other. The idea is that safe environments must be generated where one can express oneself without limitations.

G1: “…a small debate in an assembly all together, that you ask a question about a topic and each one says ‘well, I think it’s this or that’. And in the end, reach a conclusion”.

G2: “One of the resources that I would use would be the one we have done using science. Not giving the students the answer and having them debate among themselves. It seemed the most useful to me”.

G3: “It’s just that I think that listening to them… asking them what they think, and what they know. Taking their opinion into account”.

G5: “I also think that, in general, children have to be given the opportunity to speak, to express their opinions, to seek knowledge”.

Or offer a topic, an activity, or a situation freely, without the teacher providing the correct answer, giving the children an opportunity to acquire knowledge in a different way.

G4: “It consists of presenting a topic that must be resolved, but without providing specific methods to do so. Each student can devise their own approach”.

G11: “Give children space to discuss, to acquire knowledge in a different way”.

5. Discussion and Conclusions

This study explores the perceptions of students from two European universities regarding the relationship between critical thinking and its implications for sustainability, using focus group discussions. The analysis of student statements reveals both differences and similarities between the two groups. Polish students define critical thinking with an emphasis on objectivity and knowledge derived from analysis and objective data. They view critical thinking as a tool for understanding realities rationally and objectively.

By contrast, Spanish students link critical thinking to individual subjectivity, acknowledging variability among individuals and the validity of diverse perspectives, often referring to them as “my reality” or “my truth.”

These significant differences suggest a need to reconsider teacher training to include more scientific content and a deeper understanding of scientific methods for developing theories and explanations based on objective data. This aligns with Chrobak’s [29] emphasis on integrating critical thinking with meaningful learning through “learning to learn.”

The differing views on critical thinking between Polish and Spanish students have crucial implications for how knowledge is constructed and reality is understood. Polish students lean towards defining critical thinking in terms of objectivity, involving the analysis of information and situations based on verified facts and data, with critical thinking seen as a skeptical attitude towards received information. Conversely, Spanish students present a more subjective view, where each person has their own individual truth, and there’s a respect for differing opinions, even if they lack grounding in facts or data. This divergence has important implications for early childhood teacher training. Prioritizing individual perspectives over objectivity might hinder the development of knowledge grounded in shared evidence and data, which is vital for sustainability action.

Furthermore, this study found that the relationship between sustainability and critical thinking was not clearly articulated by the students, possibly indicating insufficient classroom discussion on the topic. Critical thinking was more often applied to the students’ field of study than to their roles as adult citizens and future educators, with responses often centered on children’s development.

The particular nature of early childhood education studies (e.g., psychology, didactics) appears to lack a comprehensive approach to the teacher’s role as a social agent in a changing world facing various challenges. There’s a need to move beyond solely focusing on how to best educate children to also address the teacher’s position within a globalized context. This limitation needs to be addressed to connect professional practice with its relevance in a globally interconnected world. The absence of this connection highlights a weakness in current teacher training.

Other researchers, such as Starkova and Cimermanova [30], support this, indicating that teachers often lack the knowledge to effectively develop students’ awareness of modern challenges, and emphasizing the need for incorporating Education for Sustainable Development (ESD) frameworks into teacher training. Similarly, Ekamilasari and Pursitasari [31] reveal moderate ecological awareness and low critical thinking among students, highlighting the importance of strengthening these competencies.

The OCDE [32] also emphasizes that teachers are often inadequately prepared to develop these skills, and education systems lack effective tools to assess them, particularly in the context of addressing contemporary challenges. Wiek et al. [1] stress that consolidating these standards across universities and academic communities is crucial for enhancing the role of sustainable development in higher education and its broader social impact.

Overall, students from both countries connect critical thinking with improved learning methods but less frequently with developing competencies for sustainability. A student-centered approach is favored, prioritizing classroom strategies and activities that encourage free and confident expression, fostering debates between students and teachers, and using inquiry-based learning to promote active engagement and intrinsic motivation. This contrasts with traditional teacher-centered methods like lectures and exams as the sole assessment tool. Anwer’s [33] study supports this, showing significantly higher learning outcomes for students using activity-based learning compared to those relying on lectures.

Both student groups expressed a rejection of traditional, teacher-centered methodologies. They perceive assessments associated with these methods as encouraging students to focus on passing evaluations rather than on genuine learning and development. Instead, they advocate for student-centered methodologies that consider the student’s starting point, initiative, learning capacity, and ability to debate and argue, emphasizing the importance of critical thinking for developing professional competence and sustainability competencies.

In conclusion, this study highlights significant weaknesses in initial teacher training regarding the development of critical thinking and its connection to sustainability. The conceptual differences between Spanish and Polish students indicate the influence of educational and cultural contexts on understanding critical thinking. The lack of a clear link to sustainability suggests that current teacher training efforts may not be effectively developing competencies to address socio-environmental challenges. However, the difficulties and suggestions identified by students from both countries offer valuable insights for improving teacher training programs and reorienting them towards active methodologies that integrate theory and practice, foster critical thinking, and apply it to the context of sustainability in early childhood education.

6. Limitations and Future Research

This study, while providing valuable insights into student perceptions regarding critical thinking and education for sustainable development, is subject to certain methodological limitations that warrant consideration when interpreting its findings. Firstly, the use of a non-random sampling approach, confined to specific universities in Spain and Poland, compromises the generalizability of the results. It is plausible that the unique characteristics of other higher education institutions within these countries could reveal different dynamics.

In addition, participation in this study was voluntary, which could have resulted in overrepresentation of people more interested in the subject of this study (self-selection effect).

The limited number of conducted focus group interviews, coupled with a predominance of participants from the University of Gdansk, introduces a sample imbalance that raises questions about the representativeness of the collected opinions. This geographical concentration may have biased the obtained information, limiting its applicability to broader university contexts. Furthermore, the influence of cultural context presents an inherent limitation in comparative studies. Concepts such as “critical thinking” or “sustainable development” are not universally interpreted, and cultural differences between Spain and Poland could have nuanced the participants’ responses, hindering a direct and homogeneous comparison of their perspectives.

The qualitative nature of the methodology, relying on focus group interviews and qualitative data analysis, while enabling an in-depth understanding of students’ experiences and attributed meanings, prevents the quantification of the frequency of certain phenomena and the establishment of causal relationships between the studied variables. Finally, the lack of data triangulation, with this study relying solely on student self-reports, may offer an incomplete view of educational practices. The incorporation of other data sources, such as classroom observations or curriculum document analysis, could have enriched the comprehension of the phenomenon under investigation.

To address the identified limitations and further deepen the understanding of the relationship between critical thinking and education for sustainable development in the university setting, the following avenues for future research are proposed: Firstly, it is suggested that the sample should be expanded geographically and quantitatively, including a larger number of participants and universities across various countries. This would enable more robust comparative analyses at a European and global level, identifying significant patterns and differences. Secondly, it is recommended that qualitative findings be complemented with quantitative research. The use of surveys or measurement scales could facilitate the quantification of students’ attitudes and competencies related to critical thinking and education for sustainable development, allowing for statistical analyses and the exploration of potential correlations. Finally, it is considered crucial to conduct a comprehensive curriculum analysis. Investigating the alignment between declared educational goals, implemented teaching methodologies, and actual learning outcomes achieved could offer a more holistic view of how critical thinking and sustainability are integrated and fostered within university curricula.