A Critical Consideration of Environmental Literacy : Concepts , Contexts , and Competencies

This study is based on a Delphi study on environmental literacy which is an important part of science education. The main goal is to clarify the framework, including concepts, contexts, and competencies of environmental literacy, and to reach consensus on this framework in accordance with expert opinions. This study used a mixed method research design, which included both qualitative and quantitative methods, to reveal expert opinions. The exploratory sequential design, one type of mixed method research, was used in this Delphi study and performed in three consecutive steps. The sample consisted of 45 experts who initially agreed to participate in this study, with 20 of the 45 participating in the first step Delphi. The numbers of participants in the second and third Delphi steps are 44 and 31, respectively. This study concluded there was a consensus about the definition, sub-dimensions, and competencies of environmental literacy and the institutions, social groups, and people responsible for the development of qualified environmentally-literate individuals. Additionally, there was agreement concerning what to do to support the development of environmental literacy, topics that should be included in the curriculum and textbooks, and teaching methods and extra-curriculum activities for the development of environmental literacy.


Introduction
In an ever-changing world, environmental concepts need to be updated to protect nature and natural life.In light of such updates, educational reforms are needed.The aim of this study is to update the concept of environmental literacy using a broad perspective of expert opinions from different countries.

Historical Development of Environmental Literacy
Environmental literacy in science and other disciplines is important because it enhances the protection of nature.However, environmental literacy is a concept that has evolved over time.In 1969, the concept of environmental literacy was first described [1].In 1972, environmental education gained international acknowledgement with the Stockholm Declaration [2,3].In 1976, environmental education continued through organized meetings [2].According to the Belgrade Charter [2], the environmentally literate person is defined as someone "who is environmentally competent in the affective domain, and in addition, is characterized by a values system, in which one acts consistently in a manner compatible with the balance between quality of life and quality of environment [4] (p. 252)".In 1977, UNESCO convened the first Intergovernmental Conference on Environmental Education in Tbilisi, resulting in the Tbilisi Declaration, which acknowledged the importance of environmental education in environmental conservation [5].In 1987, in light of the UNESCO-UNEP International Congress on Environmental Education and Training, an international strategy for environmental education and training for youth and adults was developed [6].In the same year, the World Commission on Environment and Development published "Our Common Future" about sustainable development [7].In the 1990s, environmental education became more rigorous for the development of environmentally literate individuals [8].Moreover, environmental education programs were designed to raise and nurture the development of environmental literacy throughout one's lifetime [9].In 1992, more than 178 governments accepted the Agenda 21 program of action for sustainable development worldwide in Rio [10].In 1993, the National Project for Excellence in Environmental Education was an effort, in part, to grapple with describing environmental literacy, as well as the need to address the education reform agenda in the United States [11].In 1997, International Environmental Education Conference members suggested that environmental education be referred to as education for the environment and sustainability in Thessaloniki [12].In 2000, the Guidelines for Excellence in Environmental Education Project provided students, parents, educators, home schoolers, administrators, policy makers, and the public a set of common, voluntary guidelines for environmental education (2000-2010) [13].In 2002, European members of the "World Summit on Sustainable Development" in Johannesburg assessed the progress of Rio de Janeiro between 1992 to 2002 and discussed a new global agreement on sustainable development [14].In 2005, UNESCO launched its Decade of Education for Sustainable Development (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014).In 2007, European and international representatives attended the conference "UN Decade of Education for Sustainable Development-the Contribution of Europe" in Berlin.During the same year, the fourth International Conference on Environmental Education in Ahmedabad reviewed the progress of the United Nations Decade of Education for Sustainable Development and reformulated Environmental Education [15].In 2014, the "World Conference on Education for Sustainable Development: Learning Today for a Sustainable Future" in Aichi-Nagoya, Japan, marked the end of the UN Decade.It celebrated its achievements and launched the Global Action Program on Education for Sustainable Development (2015)(2016)(2017)(2018)(2019).
Between 2017 and 2018, extensive research on environmental literacy was carried out with the support of the Ministry of National Education in Turkey and Bremen University in Germany.Large-scale assessments (such as PISA (Program for International Student Assessment), TIMSS (Trends in International Mathematics and Science Study), and PIRLS (Progress in International Reading Literacy Study)) should involve and evaluate elements of environmental literacy [16].As a first step, the framework of environmental literacy is revised in this study, which is a part of the environmental literacy project.

Purpose of the Research
Human needs increase daily.This situation has positive and negative effects on the environment, both directly and indirectly.However, it is necessary for individuals to be more sensitive to the environment to reduce the negative effects.This necessity also obliges the change in, and development of, the concept of environmental literacy.For this reason, studies continue to revise the components of environmental literacy and to promote environmental literacy [17].The purpose of this research is to redefine and revise the concept of environmental literacy based on experts´opinions.Thus, changes for the definition of this concept will be put forward and proposals to achieve increased environmental literacy will be presented.Experts´opinions were taken from different professions (scientists, educators, and experts on environmental education), responsible for environmental education, to conduct a comprehensive assessment of environmental literacy.

Importance of Institutions, Social Groups, and Individuals
Individuals interact with the natural environment.Nevertheless, humans have more effect on the environment if their activities are based on collective entities, such as government and non-government organizations [18].There is a need for environmentally literate individuals, which not only act individually, but also make well-informed public policy decisions collectively [13].In our world, where individuals increasingly influence the natural systems that affect their quality of life, we need to educate individuals who can influence individual and societal decisions about environmental issues [19].Therefore, we need more qualified environmentally-literate people to protect and improve the environment and natural resources as a fundamental part of humans' well-being.It is necessary to carefully determine the responsible institutions and people to protect the natural environment.Moreover, these institutions and people may increase their awareness of the importance and the development of environmental literacy.In this way, it may be possible to increase the number of qualified environmentally literate individuals rapidly.

The Importance of Science Curricula and Textbooks for Understanding Systems Related to the Environment
To achieve a more sustainable future, current and potential future environmental problems, as well as their possible solutions, are included in science curricula and textbooks to raise awareness.The environmental problems are explained to allow learners to understand the importance of issues of the natural environment.For this reason, environmental field experts and environment education provide an opportunity for authors to determine what environmental issues should be addressed and how those issues should be explained in science curriculum and textbooks.The Sustainable Development Strategy Study by the European Union is a good example.In 2006, the European Council determined seven key priority challenges for sustainable development [20]: climate change and clean energy; sustainable transport; sustainable consumption and production; conservation and management of natural resources; public health; social inclusion, demography, and migration; and global poverty and sustainable development challenges.
Sustainable development and its influences are key issues in the environmental field.Therefore, when preparing curricula or textbooks, the concept of environment should be presented with a broad perspective.Science curricula contain many interrelated systems related to the environment.For instance, human systems (such as political, economic, and cultural systems and their relationships) and interactions with physical and living systems are included in the scope of environmental literacy [21].On the other hand, socio-ecological systems related to the environment include the understanding of many aspects of science, especially chemical and physical change, carbon cycling, water cycling, biodiversity, and evolution by natural selection [22].In addition, socio-scientific issues, related to both social and environmental aspects, continue to be one of the basic concepts of science curricula.Current examples of socio-scientific issues are stem cell research, genetic engineering, cloning, and environmental problems [23].Nowadays, the relationship between engineering and environmental systems is increasing in importance, which is recognized in science education and curriculum development in the field of Science, Technology, Engineering, and Mathematics (STEM) education.There is a need for further research about how individuals are influencing environmental systems [24] and how to integrate engineering and environmental systems effectively.Simmons suggests the components of environmental literacy in the environmental education framework are: affect (e.g., environmental sensitivity, attitude, and moral reasoning); ecological knowledge; socio-political knowledge (e.g., the relationship of cultural, political, economic, and other social factors to ecology and environment); knowledge of environmental issues, skills regarding environmental problems or issues, and action strategies, systemic thinking, and foresight; determinants of environmentally responsible behavior; and behavior (solving problems and resolving issues) [25].Moreover, according to Hines, Hungerford, and Tomera's results of the meta-analysis, it is concluded that the variables of "knowledge of issues", "knowledge of action strategies", "the locus of control", "attitudes", "verbal commitment", and "an individual's sense of responsibility" are associated with responsible environmental behavior [26].
Science curricula and textbooks that address environmental literacy may also provide opportunities to protect the natural environment and promote its effective use.Furthermore, science curricula and textbooks may be educational tools that help individuals learn concepts related to the natural environment and to put them into practice.Therefore, efficient science curricula and textbooks are some of the factors that contribute to the development of environmental literacy.

The Impact of Teaching Methods and Extra-Curricular Activities on Achievement
The educational environment and activities provided to students are major factors affecting student achievement [27].For this reason, teachers should use different teaching methods in the classroom and in their lectures.
Through these methods, the cognitive, emotional, and psycho-motoric skills of the students at diverse levels are developed more effectively to increase academic achievement and to promote the education of qualified environmentally literate individuals.
Different teaching methods, such as cooperative learning [28][29][30], varied discussion methods, inquiry-based learning [31][32][33], and project-based learning [34,35], have a positive impact on student achievement and learning.Moreover, individuals trained in new pedagogical education should have the skills, talents, and motivations to plan and manage change towards sustainability within a social environment [36].
On the other hand, improving the skills, talents, and motivations of students takes place inside as well as outside the schools.Extra-curricular activities (ECA) are any activities that occur outside of the school curriculum [37].ECA provides opportunities for students to develop their motivations (such as moral and cognitive attitudes) and skills, as well as to collaborate and communicate with their peers [38,39].Students who participate in ECA have a chance to gain self-confidence and independence [40].Moreover, ECA have a positive effect on environmental literacy [41].Therefore, these activities have become paramount elements of students' education and many schools allocate important resources to these activities [42].Non-mandatory ECA for students include activities such as discussions and workshops to achieve specific goals [43].The experiences gained from ECA contribute to the social progress and individual development of the students [44].Even though all activities that take place in out-of-classroom settings are not beneficial for student success [45], ECA have an overall positive effect on academic success at different academic levels (both school and university level) [40,[46][47][48].

Research Questions
The goal of this study was to clarify the framework (concepts, contexts, and competencies) of environmental literacy and to reach consensus on this framework based on experts´opinions.Within the scope of this aim, answers to the following questions were sought: Q1: How do experts define environmental literacy?Q2: Which concepts and contexts are included in the framework of environmental literacy?Q3: What are the competencies of the environmentally-literate individual?Q4: What should be done to promote the development of environmentally literate individuals?

Materials and Methods
In this study, a mixed method research design was used to reveal expert opinions about the concept of environmental literacy.This type of research design combines qualitative and quantitative data [49] (p.14), which provides a more comprehensive coverage of the research topic [50].The exploratory sequential design, a type of mixed method research, was used.Through the exploratory sequential design, the results of qualitative research are the basis for subsequent quantitative research, as can be seen in Figure 1 [51].Based on experts´ opinions, the Delphi technique was utilized to determine the concept of environmental literacy and to develop the competencies of the environment literate individual.The Delphi technique is used for the collection of views on a specific topic [53].It is a research technique used to obtain a common result using expert opinions to solve a complex problem [54].This technique usually involves consecutive questionnaires directed to experts [55] and allows them to explain their opinions freely without being influenced by the views of others [56].In the Delphi technique, qualitative, quantitative, or mixed method research can be utilized [57].Therefore, the combined use of both the mixed method and the Delphi study techniques helps to uncover, define, and reach consensus on the best practices and specific situations for the research topic [50].
In this study, as shown Figure 1, the Delphi study was performed in three consecutive steps.First, the qualitative data was collected.After the analyses of the data, the quantitative form was developed for the second step of the Delphi study.After the analyses of the data collected in the second step, the final quantitative form (for the third step) was prepared.

Sample
In a Delphi study, the selection of the sample is crucial [58].The target sample population is experts in the area the researcher is assessing [59] to ensure the highest quality data [60].The selection of experts in the field increases the reliability of Delphi studies.At this point, the characteristics of the universe are determined, and individuals with these characteristics can be selected for sampling [61].There must be at least seven experts in the sample, but the ideal group size is 10 to 20 experts.[62].On the other hand, if the group is chosen homogeneously, a small sample (10 to 15 participants) may yield enough outcomes [57].Therefore, experts with a Ph.D. specializing in environmental education were included for the creation of a homogeneous sample.These experts within the homogeneously selected sample worked at different universities in different countries to ensure maximum variation in the sample.Initially, 45 experts who work as scientists, educators, and teachers in countries of the European Union and candidates' countries of the European Union (40), the United States, and Africa (5) agreed to participate.However, the numbers of the participants in the first, second, and third Delphi study steps were 20, 44, and 31, respectively.

Process of the Delphi Study
The Delphi technique prevents participants' direct discussion with each other, and through interviews or questionnaires, participants can question the situation repeatedly [63].It is used as a means of providing consensus among experts in situations where there are differences of opinion [64].In this study, the Delphi study was carried out in three steps, as seen in Figure 2.Each round contained the data collection tool, the collection of data, and the analysis of these collected data.Based on experts´opinions, the Delphi technique was utilized to determine the concept of environmental literacy and to develop the competencies of the environment literate individual.The Delphi technique is used for the collection of views on a specific topic [53].It is a research technique used to obtain a common result using expert opinions to solve a complex problem [54].This technique usually involves consecutive questionnaires directed to experts [55] and allows them to explain their opinions freely without being influenced by the views of others [56].In the Delphi technique, qualitative, quantitative, or mixed method research can be utilized [57].Therefore, the combined use of both the mixed method and the Delphi study techniques helps to uncover, define, and reach consensus on the best practices and specific situations for the research topic [50].
In this study, as shown Figure 1, the Delphi study was performed in three consecutive steps.First, the qualitative data was collected.After the analyses of the data, the quantitative form was developed for the second step of the Delphi study.After the analyses of the data collected in the second step, the final quantitative form (for the third step) was prepared.

Sample
In a Delphi study, the selection of the sample is crucial [58].The target sample population is experts in the area the researcher is assessing [59] to ensure the highest quality data [60].The selection of experts in the field increases the reliability of Delphi studies.At this point, the characteristics of the universe are determined, and individuals with these characteristics can be selected for sampling [61].
There must be at least seven experts in the sample, but the ideal group size is 10 to 20 experts [62].On the other hand, if the group is chosen homogeneously, a small sample (10 to 15 participants) may yield enough outcomes [57].Therefore, experts with a Ph.D. specializing in environmental education were included for the creation of a homogeneous sample.These experts within the homogeneously selected sample worked at different universities in different countries to ensure maximum variation in the sample.Initially, 45 experts who work as scientists, educators, and teachers in countries of the European Union and candidates' countries of the European Union (40), the United States, and Africa (5) agreed to participate.However, the numbers of the participants in the first, second, and third Delphi study steps were 20, 44, and 31, respectively.

Process of the Delphi Study
The Delphi technique prevents participants' direct discussion with each other, and through interviews or questionnaires, participants can question the situation repeatedly [63].It is used as a means of providing consensus among experts in situations where there are differences of opinion [64].In this study, the Delphi study was carried out in three steps, as seen in Figure 2.Each round contained the data collection tool, the collection of data, and the analysis of these collected data.The development of questionnaire forms and data analysis methods are structured according to the three steps [66].However, in the Delphi method, qualitative data from the first round is obtained, and then this data provides the basis for the quantitative data in both the second and third rounds [67].

First Round
For the first round of the Delphi study, a questionnaire including structured open-ended questions and demographics was used to receive participants' opinions, both using paper and pencil forms and interviews.In light of the literature, 13 questions were asked in the draft questionnaire.After the feedback and review of two scientists (communicative validation), the final version of the questionnaire contained nine questions that were hierarchically ranked (Appendix A).The structured open-ended questionnaires were sent to all participants and interviews were also conducted with three randomly selected experts.In the first step Delphi, 20 of the 45 experts participated.The data obtained in the first round were analyzed using the content analysis method, which allows researchers to identify collected data and reveal hidden information in the data [68].Content analysis helps to identify the concepts and categories that explain the collected data [69].

Second Round
The responses from the first round were converted into Likert-scale items.In the survey, a 7item Likert-scale was used between "Strongly agree" (7) and "Strongly disagree" (1).Moreover, the experts could share their opinions for each item in the questionnaire.By this means, participation levels for each item were determined.For the validity and reliability of the prepared questionnaire, opinions were taken from two scientists related to environmental education and one linguist.A pilot study involving 36 experts was conducted.The obtained reliability results are given in Table 1.The development of questionnaire forms and data analysis methods are structured according to the three steps [66].However, in the Delphi method, qualitative data from the first round is obtained, and then this data provides the basis for the quantitative data in both the second and third rounds [67].

First Round
For the first round of the Delphi study, a questionnaire including structured open-ended questions and demographics was used to receive participants' opinions, both using paper and pencil forms and interviews.In light of the literature, 13 questions were asked in the draft questionnaire.After the feedback and review of two scientists (communicative validation), the final version of the questionnaire contained nine questions that were hierarchically ranked (Appendix A).The structured open-ended questionnaires were sent to all participants and interviews were also conducted with three randomly selected experts.In the first step Delphi, 20 of the 45 experts participated.The data obtained in the first round were analyzed using the content analysis method, which allows researchers to identify collected data and reveal hidden information in the data [68].Content analysis helps to identify the concepts and categories that explain the collected data [69].

Second Round
The responses from the first round were converted into Likert-scale items.In the survey, a 7-item Likert-scale was used between "Strongly agree" (7) and "Strongly disagree" (1).Moreover, the experts could share their opinions for each item in the questionnaire.By this means, participation levels for each item were determined.For the validity and reliability of the prepared questionnaire, opinions were taken from two scientists related to environmental education and one linguist.A pilot study involving 36 experts was conducted.The obtained reliability results are given in Table 1.Each construction contained 5 to 13 questions.The Cronbach's alpha coefficients of these constructions ranged from 0.92 to 0.70.Moreover, the Spearman-Brown split-half reliability coefficient was used (0.92).

Third Round
The items in the third questionnaire were the same as in the second round questionnaire.By considering the results of the second round, a question was added to the definition and sub-dimensions of environmental literacy, and other experts' opinions were sought in this regard.The difference between the third and second questionnaires was that the statistical data (arithmetic mean, standard deviation, and quartile difference) obtained from the second questionnaire were shared with participants in the third questionnaire.In this respect, the participants had the opportunity to evaluate each item while considering the statistical data from the second round.

Methods of Data Analysis
To understand whether consensus was reached statistically, the mean (x), standard deviation (sd), median (med), difference between quarters (DBQ), percent of responses, consensus (cons), and consensus difference between the second and third round analyses (cons.dif.) are given in the tables.Table 2 describes how consensus was determined.If the median was greater than or equal to 5, the DBQ was less than or equal to 1.5, and the frequencies of "agree" (Likert-scale of 5-7) were greater than or equal to 70%, consensus was reached.In this study, consensus is reached for each item if the median is greater than 5 (I), the DBQ is less than or equal to 1.5 (II), and the frequencies of "consensus" are greater than 70% (III).On the other hand, if each of the three criteria is not met, consensus is not reached.

Results
The results obtained at the end of the first round were used in both the second and third rounds.Each question represents each theme and each item represents each code.Therefore, the results obtained from the first round are not included in this section.The frequency and percentage values were calculated and depicted in the second and third rounds.The responses given by the experts on the 7-point likert scale were grouped in 3 categories (1-3: no consensus; 4: Neutral; 5-7: consensus).In addition, the numbers of the experts in the second and third Delphi round were 44 and 31, respectively.
As seen in Table 3, at the end of Delphi study, consensus was reached for all items except interrelationship of knowledge, understanding, attitude, morals and ethics, and intention and behavior towards the environment.In addition, there was consensus on the concept added to the definition of environmental literacy based on expert opinions at the end of the second round (improved skills to evaluate data, draw conclusions, and form opinions), which is related to the cognitive dimension.As seen in Table 4, at the end of Delphi study, consensus was reached on all sub-dimensions of environmental literacy.However, no consensus was reached on the item legislation about the environment, which was added to the third round.When the second and third Delphi results are compared, the percentage of environmental attitudes and motivation, morals, and ethics related to the environment, sustainability is increased.
As seen in Table 5, at the end of Delphi study (third Step), consensus was reached on all items regarding what is necessary to achieve environmental literacy.However, there was no agreement about concrete sustainable activities towards the environment in the step 2 Delphi.When second and the third Delphi results are compared, the percentage of responsibility towards the environment, social engagement related to the environment, positive behavior towards the environment, sustainable knowledge about the environment, and concrete sustainable activities towards the environment are increased.As seen in Table 6, at the end of Delphi study, there was a consensus on all items regarding the institutions that are responsible for the development of environmentally literate individuals.When the second and third Delphi results are compared, the percentage of state, ministry of education, industries, citizen associations, and public media are increased.As seen in Table 7, at the end of Delphi study, there was a consensus on seven items (family, individual (themselves), educators, academics, scientists, teachers, and policy makers) who have responsibility for the development of qualified environmentally literate individuals.However, there was no consensus on the remaining six items (friends, employees who work at schools, country administrators, entrepreneurs, business people, and artists).The institutions and social groups and people that have a responsibility for the development of qualified environmentally literate individuals are varied.Experts believe that states and public media are responsible for the development of environmentally literate individuals; however, country administrators who manage the states and artists are not responsible.In addition, people (business people and entrepreneurs) who work in industry are not responsible for the development of environmentally-literate individuals, however, industries are responsible.
Business people 2.R. 5.58 1.80 6.00 2.00 As seen in Table 8, at the end of Delphi study, there was a consensus on 11 items about what should be done to enhance the development of environmentally literate individuals.When the second and third Delphi results are compared, the percentage of "the family should inform their children about environmental issues", "the family and teachers support their children to gain positive attitudes towards the environment", "teachers should support their students to gain intentions to act with and show environmentally-friendly behavior", "in science curricula, more environmental topics and their practices should be included", and "non-government organizations and public media should support individuals to take part in social and to learn about environmental issues" are increased.
As seen in Table 9, at the end of Delphi study, there was consensus on seven items regarding topics that should be included in the curricula and textbooks for the development of environmental literacy.When the second and third Delphi results are compared, the percentage of environmental perceptions, examples of environmentally-friendly behavior, and social perspectives are increased.As seen in Table 10, at the end of Delphi study, there was a consensus on all items except for knowledge transmission (direct instruction, expository instruction) and documentaries and videos.At the end of the second round, there was a consensus on knowledge transmission, which disappeared at the end of the third round.Teachers should use varied teaching methods in science classes for development of environmental literacy, such as out-of-school activities, collaborative learning, inquiry-based learning, project-based learning, experiments, context-based learning, problem-based learning, varied discussion methods, and hands-on experiences.As seen in Table 11, although there was no consensus on the items of "watch TV programs about the environment", "read a book or newspaper about the environment", and "visit museums of science and the arts" in the second round, there was consensus on "visit museums of science and the arts" in the third round.There was consensus on "visiting botanical gardens" in the second round, but there was no consensus at the end of the third round.
These research findings emphasize that teachers should be supported both for individual and professional development to educate qualified, environmentally-literate individuals.In addition, teachers should be aware of the importance of teaching methods (project-based learning, problem-based learning, etc.) and ECA (participate in environmental club and activities, field trips, and excursions, etc.) for the development of environmental literacy.

Discussion and Conclusions
According to the results of the second step Delphi, there was no consensus on 17 of 81 items.Therefore, the third step of the Delphi study was necessary.The third step Delphi study improved to a lack of consensus on 12 of 81 items.In the light of expert opinions, the concepts that need to be included in the definition of environmental literacy are "knowledge and understanding of environmental issues", "attitudes and concern towards the environment", "morals and ethics towards the environment", and "intent to act with environmentally responsible behavior", as well as, "promotion of skills to evaluate data, draw conclusions, and form opinions".
The current definition of environmental literacy includes common concepts, such as the ability to perceive, interpret, and make informed decisions about environmental issues, understand ecosystems, and be aware of the importance of natural phenomena [1,70,71].This study expands on this definition and shows that it is necessary to include concepts of morals and ethics towards the environment; knowledge, understanding, attitude, morals and ethics, and intention and behavior towards the environment; and development of skills to evaluate data, draw conclusions, and form personal opinions in the definition of environmental literacy.Additionally, the sub-dimensions of environmental literacy are knowledge and understanding about environmental issues, environmental attitudes, environmental motivation, morals and ethics related to the environment, intention to act in an environmentally-friendly manner, environmentally-friendly behaviors, and sustainability.
Common sub-dimensions related to environmental literacy are knowledge, attitudes, values, skills, responsibility, and active involvement [1,5,72].Future environmental literacy research should include morals and ethics, motivation, and sustainability.Besides attitude and behavioral control, personal moral norm is a variable of pro-environmental behavioral intention [73].In light of expert opinions, environmental literacy competencies that come to the forefront are knowledge and understanding about environment issues, responsibility towards the environment, awareness of environmental issues, motivation towards the environment, morals and ethics regarding environmental issues, social engagement related to the environment, intention to act to protect the environment, positive behavior towards the environment, sustainable knowledge about the environment, and concrete sustainable activities towards the environment.
Teaching skills and a teacher's disposition are important for the development of qualified, environmentally-literate individuals [41].Therefore, it is necessary to focus on teacher training and professional development, especially on the use of effective teaching methods for teaching and integrating environmental issues into the curricula [74].The following topics should be included in the curriculum and textbooks for the development of environmental literacy:

•
Environmental perceptions (attitude, responsibility, morals, etc.);In general, concrete examples and predicted future environmental problems should be emphasized more than the theoretical concepts related to biology in the curricula and textbooks.However, in general, environmental knowledge are highly emphasized in the school curriculum [75].In addition, for the development of environmental literacy, it is crucial to be aware of the importance of ECA, such as visiting web sites of environmental organizations, participating in environmental clubs, visiting science and art museums, and taking field trips.ECA not only have a positive effect on achievement at different academic levels [40,[46][47][48], but also promote student passions, skills, cooperation, and communication with their peers [38,39].The educational interventions can effectively enhance environmental behavior [76].Moreover, ECA have a positive effect on environmental literacy [41].The study shows that the active involvement and social engagement related to the environment and the importance of ECAs in promoting cooperation and communication with peer, and suggestions are shared about ECA examples for the development of environmental literacy based on expert opinions.
Authors should discuss the results and how they can be interpreted with respect to previous studies and of the working hypotheses.The findings and their implications should be discussed in the broadest context possible.Future research directions may also be highlighted.

Recommendations
Based on the research results, the scope and definition of environmental literacy were revised in line with the opinions of experts.Moreover, the competencies of environmental literacy were enumerated.Therefore, our results should not only guide curriculum developers, researchers, and stakeholders, but also suggest what teachers should do to educate qualified, environmentally-literate individuals.
The new definition of environmental literacy based on our results is "knowing and understanding environmental issues; having attitudes, concerns, morals, and ethics towards the environment; having the ability and intention to act with environmentally responsible behavior; having the active involvement and social engagement related to the environment, as well as having skills to evaluate data and draw conclusions to form one's own opinion and collaboratively working with stakeholders to solve environmental issues." Researchers and curriculum developers should consider this definition of environmental literacy and the seven sub-dimensions and ten competencies when evaluating environmental literacy.Teachers have a significant role in educating environmentally literate individuals.In the teaching process, teachers should use the project-based learning approach, varied discussion methods, out-of-school activities, and collaborative learning instead of direct instruction and expository instructional teaching.Moreover, our results show teachers' professional development is a key factor that affects the development of environmentally-literate individuals.Thus, qualified, environmentally-literate individuals require qualified, environmentally-literate teachers.
Additional environmental education should become part of the academic teacher training programs in universities.In particular, the concept of "environment" should be integrated into the framework of PCK for teachers' professional development.Teachers, as well as families and governments, have an important responsibility for directing and encouraging students to attend ECA, such as participating in environmental clubs and activities, visiting science museums, and utilizing out-of-school environments.In addition, curriculum developers, program developers, and authors should include the concepts of environmental perceptions, examples of environmentally-friendly behavior, environmental problems and their solutions, sustainability, and social perspectives to enhance environmental science curricula and books.Moreover, teacher training and practices should be developed to teach these concepts and context in teacher education.
Finally, the development of quality environmental literacy education will depend on the quality of education and teacher training, quality of science curricula and textbooks in school systems, family engagement, as well as initiatives from environmentally sensitive governments and non-government organizations.Teachers and their students should be supported by corporations of both governments and non-governments.Governments, families, teachers, non-governments organizations, and public media should support the development of qualified environmental literacy.The families and teachers should inform children about environmental issues, promote the acquisition of morals and ethics towards the environment, and guide the development of positive attitudes towards the environment.Moreover, teachers should support student development of intentions to act and show environmentally-friendly behavior.Governments should mandate the inclusion of more environmental topics and their practice in science curricula and support the environmental qualifications of their teachers.Non-government organizations should support participation in social, civil, and societal initiatives.Public media (newspapers, TV, etc.) should support learning about environmental issues.

Table 3 .
Components of the definition of environmental literacy.

Table 4 .
Sub-dimensions of environmental literacy.

Table 5 .
Competencies of environmental literacy.

Table 6 .
Institutions and social groups responsible for the development of qualified environmentally-literate individuals.

Table 7 .
People responsible for the development of qualified environmentally-literate individuals.

Table 8 .
What to do to support the development of environmental literacy.

Table 9 .
Topics that should be included in the curriculum and textbooks for the development of environmental literacy.

Table 10 .
Teaching methods for the development of environmental literacy.

Table 11 .
Views regarding extra-curriculum activities for the development of environmental literacy.