Environmental Content as a Part of Science-Oriented Sustainable Development Goals in Grades 6 and 7 of Slovenian Primary School: An Analysis of Science Textbooks

• Slovenian science education in Grades 6 and 7 (11-and 12-year-old students) of primary school focuses on the integration of various science subjects. According to the current Slovenian science curriculum, environmental concepts, as a part of science-oriented sustainable development goals, are an integral part of the subject of science. In 2026, a new science curriculum will be introduced in the education system to provide students and teachers with competences for sustainable development. Consequently, the aim of this study is 1) to analyse old (valid prior to the 2010/2011 school year) and current 6th and 7th-grade Slovenian science curriculum for primary school from an environmental and sustainability perspective, and 2) to investigate textual and pictorial material of four 6th grade and four 7th grade textbooks available for students in the current school year (2023/24) of primary school, that relate to environmental content, as well as their overall structure. The analysis of the textbooks showed that all textbooks explain some environmental topics recommended by the national curriculum. The text is supported by pictorial elements that present phenomena with realistic pictures on the macrolevel. The present study suggests that some environmental content is present in 6th-and 7th-grade science textbooks that are consistent with the learning goals of the curriculum but that a significant amount of sustainability content is missing. For this reason, the curriculum reform currently underway in Slovenia should more clearly include the implementation and thoroughly consider the integration of science-oriented sustainable development goals into the science curriculum in Grades 6 and 7.


Introduction
Environmental issues have recently become one of the most emphasised topics as a result of globalisation, the media, and the impact of its consequences on people's daily lives (Laçin Şimşek, 2011).The realisation that environmental problems are related to human beings brings with it the need to raise individuals' awareness of the environment and the negative impact humans have on it.The agenda of the European Union and the United Nations now and in the near future is to create an adequate environment for future generations, focusing on sustainable development and a green transition.Following various guidelines (Bianchi et al., 2022;Mulvik et al., 2021;Rieckmann et al., 2017) to achieve the established goals, the school system worldwide is attempting to adapt to meet these criteria (Freire et al., 2016).
As Jimenez et al. (2017) report, environmental content is one of the most important dimensions of education for sustainable development.Nearly all levels of education, especially science education, promote either sustainable development or education for responsible citizens (Eilks, 2015), so when teaching the concept of sustainability in science education, a link should be made between science and sustainability concepts (Quinn et al., 2015).With the environmental competences acquired through environmental education, students take their place in society as citizens of the future to build a better future in a sustainable way (Erjavšek et al., 2021;Rauch & Steiner, 2013).Roczen (2011) defined environmental competencies as a model that describes the interconnectedness of environmental knowledge in relation to nature and a person's ecological attitudes and behaviour.Environmental competencies and sustainable development competencies are closely intertwined, often complementing each other within the broader framework of sustainable development (Agbedahin, 2019;Kopnina, 2020).
One of the basic educational materials that students need for learning school subjects is textbooks.They are usually the primary source of information and the most important educational resource of information for students' learning (King, 2010;Martin et al., 2011;Stará et al., 2017).Students use textbooks at school, for learning at home, and sometimes cite them as a reference for further work and projects that go beyond the national curriculum of a particular school subject (Gkitzia et al., 2011).In this context, science textbooks with environmental education concepts have great potential for learning about science-based sustainable development goals.
There are many definitions of a textbook, but the legal definition is contained in the Slovenian Regulation of Textbook Approval (Pravilnik o potrjevanju učbenikov) from 2015 and states: The textbook is a basic learning material for achievement of educational aims and standards of knowledge, defined in the curriculum or in the catalogue of knowledge.It supports teaching and learning with didactic-methodical organization of content and adapted illustrations and graphical layout.The content and the structure of the textbook allow for independent learning of the participants of education and the acquisition of different levels and categories of knowledge.The textbook should not require any direct insertion of answers or solutions either written or drawn, save in the case of the textbook, designed for the use in electronic form (further e-textbook), that can allow for the direct insertion.The textbook is tied to the school subject or a topical-didactical set, grade and the level of education.A reader as a compendium of texts chosen in accordance with the aims of curriculum is also a textbook" (Regulation of textbook approval, 2015, Art.2.1).
In order to be approved, the textbook must meet the conditions set out in the regulations cited above and is reviewed by experts from the individual subject areas.
The catalogue of approved textbooks is published by the Ministry of Education of the Republic of Slovenia and is available on the Ministry of Education's website.Many criteria have been published for the creation of textbooks in Slovenia (Devetak & Vogrinc, 2013), stating that a textbook should be comprehensible and transparent, that the pictorial elements should be of high quality, that the content should be in line with the objectives of the educational programme and be well-rounded, that the content should also be in line with the educational goals in the national curriculum of the subjects, that the textual and pictorial material should be scientifically accurate and promote the development of general and specific competences in the respective scientific field.
Ultimately, a textbook should promote active learning, include activities at various levels of knowledge and incorporate aspects of interdisciplinarity (Devetak & Vogrinc, 2013).In Slovenia, it is common for textbooks to be approved for the next school year every year.If there is more than one approved textbook for a subject, teachers are often faced with the dilemma of which textbook to use.They should choose the textbook that will help them the most in the classroom and with which they can achieve the learning objectives.Kalin (2004) presents six basic factors that should influence the choice of teaching materials or textbooks: 1) purpose and objectives of teaching, 2) learning content, 3) teaching methods and approaches, 4) characteristics of the social environment, 5) characteristics of the students and the teacher, and 6) characteristics of the educational material itself.Finally, the textbook is an important element for all participants in the conventional classroom-centred learning environment (King, 2010).In such a conventional classroom-centred learning environment, textbooks enable teachers to achieve the objectives set out in the curriculum and guide them in their teaching (Martínez-Gracia et al., 2006).
With the rapid development in information and communication technology and with the transition to online teaching triggered by the Covid-19 pandemic, learning and teaching have inevitably evolved from a traditional, classroombased, textbook-centred process to a more flexible, e-learning-resource-oriented learning one (Dunn et al., 2022;Lau et al., 2018).
Research has often provided inconclusive results regarding students' preferences for digital textbooks compared to print textbooks and their achievement (Johnston & Salaz, 2019).by Roberts (2021) showed that students were equally successful when using e-textbooks or paper textbooks.Paivio (1991) presented a dual coding theory that explains two ways of taking in information while learning certain content: verbal associations and visual imagery.The visual system deals with the processing of graphic information, while the verbal system deals with the processing of linguistic information.Paivio's theory states that both verbal and visual information are used to represent information (Paivio, 1991;Sternberg, 2003).Based on these assumptions, Paivio suggested that learners have twice the chance of acquiring the information if it is encoded both visually and verbally, as the information is physically presented as a whole.According to this theory, textbooks that promote learning should convey the information to be processed in both textual and pictorial ways.
It is important that the texts in the textbook are written clearly and comprehensibly and that the professional terminology is explained.Reading, writing, and oral communication skills are necessary for students to understand the professional texts in the textbooks (Lemke, 1998;Martínez-Gracia et al., 2006).If they lack these skills, they will have problems understanding the professional texts.Peacock and Gates (2000) have shown that the structure of the text is not so important and does not contribute significantly to the quality of learning.Guidelines for the evaluation of textbook texts should therefore be: 1) the text must be stylistically appropriate (the writing style should be clear and close to everyday life); 2) the material should be didactically adapted to the needs of the target group of students (e.g., adapted to the average cognitive development of students at the respective educational level); 3) the material should contain elements that arouse the students' interest in learning a particular scientific content (e.g., life stories, case studies, problem-solving, adequate pictorial material etc.); 4) the material should promote active learning; and (5) the material should include activities at various cognitive levels of knowledge (stepwise from knowledge to synthesis and evaluation) (Peacock & Gates, 2000;Devetak & Vogrinc, 2013).
An important part of the textbook is also the tasks in or at the end of each chapter, which allow students to consolidate and test their knowledge (Holcar, 2009) and give students personal insight into the knowledge acquired in the chapter.
A textbook without pictorial material is no longer conceivable today.Not only does the pictorial material make textbooks more attractive and dynamic, but it also breaks up the monotony of the text and contributes to the successful transfer of knowledge and, as Dimopoulos et al. (2003) report, to better understanding.The criteria for evaluating the pictorial material in the textbook include some important aspects such as: 1) it should be of high quality; 2) it should contain elements that stimulate students' interest; 3) it should promote the recall of what is already known and stored in students' long-term memory; 4) it should be specifically linked to the text; 5) it should be of different types; 6) the multidisciplinary aspect of the pictorial material should be emphasised; and 7) the pictorial material should complement the activities presented in the textbooks (Stylianidou et al., 2002;Cook, 2008;Devetak & Vogrinc, 2013).
In contrast, Stylianidou et al. (2002) reported that images can often cause additional problems for students in understanding the specific text in a textbook if they are not logically integrated into the text and their sole purpose is to fill the empty space and not to provide additional illustration to the text.However, a cognitive theory of multimedia learning (Mayer, 1997) suggests that the learner goes through three important cognitive processes: 1) selecting: verbal information yields a textbase and visual information yields a picture base; 2) organising, applied to the word base to create a verbally based model of the system being explained and is applied to the picture base to create a visually based model of the system being explained; and 3) integrating: occurs when the learner makes connections between corresponding events (or states or parts) in the verbally based model and the visually based model.These processes should be utilised by the learner when using the textbook.This theory states that it is better to present an explanation in words and pictures together than in words alone, and it extends Paivio's dual coding theory of learning mentioned earlier.Reid et al. (1983) suggest that visual-verbal learning allows students to reconcile the two modes and carefully compare the information available in the picture with the explanation in the text.In a study of six science textbooks, Mayer (1993) concluded that illustrations accounted for 55% of the printed space.Cook (2008) suggested that because a large proportion of science textbooks consist of diverse visual material, more attention needs to be paid to understanding the impact of pictorial material on students learning.
For science textbooks, the pictorial material can be divided into two categories:(1) pictorial materials Type I (realistic, conventional, and hybrid images) and 2) pictorial materials Type II (images that comprise macroscopic, submicroscopic, and symbolic levels of representations of science concepts).Realistic images represent reality (e.g., photos or drawings).Conventional images are graphs, diagrams, maps, molecular structures, and similar, while hybrid images combine realistic and conventional images (Dimopoulos et al., 2003).Macroscopic images represent experimental phenomena or other natural phenomena at the sensory level, while submicroscopic images visualise the particulate level, such as atoms, ions, and molecules.Symbolic images present symbolic chemical language (e.g., symbols of elements, chemical formulas, chemical equations, mathematical equations, etc.) (Johnstone, 1982;Devetak et al., 2010).
In modern textbooks, the pictorial and textual material presented in textbooks could be upgraded in e-textbooks.The development from traditional textbooks to e-textbooks has opened new dimensions in the presentation of learning materials.The integration of various multimedia elements, such as videos, animations, and simulations of natural processes, not only enhances the visual and textual components but also contributes significantly to the overall value of the students' learning experience and promotes their digital literacy (Shalgimbekova et al., 2023).

Environmental contents in science textbooks and science curriculum
Environmental topics became increasingly important in the second half of the 20 th century, mainly due to global environmental content (Bromley et al., 2011).Therefore, environmental education has started to be included in school curricula and textbooks.
In Slovenia, two major revisions of primary school curricula have been conducted in the previous three decades.The primary school curriculum was first adopted in 1998 (old curricula) by the Expert Council for General Education of the Republic of Slovenia in accordance with the curriculum guidelines prepared by the National Curriculum Council in 1996.In the period between 2007 and 2011, the second and last major curriculum renewal took place, which was completed in 2011 (current curricula).One of the focuses of this study is also to analyse the above-mentioned curriculum for science education in Grades 6 and 7 of primary school.
European Commission funding for post-pandemic recovery represented an opportunity for Slovenia to renew national curricula across the education chain.Slovenia, therefore, committed to renewing its education system and the national curriculum in primary and secondary schools in 2021 as part of the Recovery and Resilience Plan (RRP).The aim of the renewal of educational programs is to provide students and teachers with competences that are important for coping with current and future challenges (digital competences, competences for sustainable development, mechanisms for caring for (mental and physical) health and entrepreneurial competences) in order to strengthen the resilience of the education system.This began in 2022 with the adoption of the starting points for the renewal of the main program documents and is expected to continue until its completion in 2026 when new curricula will also be introduced into the education system for science and other subjects.For these reasons, the analysis of the two previous curricula is presented here from an environmental and sustainability perspective.
While students learn about forests, inland waters, oceans, and similar., they are also exposed to environmental content that focuses on the human impact on these ecosystems.The question, however, is how this content is taught and, more importantly, how much time and in what way environmental topics are integrated into the classroom as suggested in textbooks and curricula.As part of the RRP, the new science curriculum to be introduced in the 2026/27 school year will include sustainable development and green and resilient transition competences, among others.
The environmental content in the curriculum is often designed as crosscurricular activities, which means that teachers should incorporate it into a variety of subjects, curricular and extra-curricular activities, and science days.Environmental education should be integrated into the whole educational process, as this is the only way it can lead to the development of students' environmental competences and the formation of an environmentally aware citizen.Although the content that can stimulate the development of specific environmental skills in students can be found in textbooks and curricula, research (Lane & Wilke, 1994;Wade & Eland, 1995;Ernst, 2007Ernst, , 2009;;Rebolj & Devetak, 2012) shows that problems arise when teaching environmental content.One of them is the lack of knowledge about environmental content among teachers and the lack of time to prepare for teaching environmental content.Other obstacles include lack of training or opportunities for continuous professional development, lack of technical support, safety concerns, responsibility for teaching outside the classroom, lack of financial resources, lack of interest and support from local partners, and lack of support from parents (Rebolj & Devetak, 2012;Yurtsever & Angın, 2022).

Purpose of the study and research questions
Authors of the educational material should consider the criteria for quality material and, following them, prepare the textual and supporting pictorial elements appropriately.According to the above literature review, it can be assumed that only properly presented content in the textbook can help develop students' understanding of environmental concepts with fewer misconceptions.Devetak et al. (2010) conducted an analysis of Slovenian science and chemistry textbooks regarding selected chemistry concepts (Grades 1-9), but no attempt was made to analyse the textbooks from the perspective of environmental concepts in Grades 6 and 7. Therefore, this study focused on the most commonly used science textbooks in Slovenian primary schools for these grades and the curriculum for science in Grades 6 and 7.
The aim of this study is to examine how environmental concepts are presented to 11-and 12-year-old students in Slovenian science textbooks for Grades 6 and 7 of primary school from a textual and pictorial perspective.In addition, the aim was to examine how the science curriculum changes from the environmental competences perspective from the old to the current one.The textual material was analysed to determine what didactic elements are included in the textbooks and how environmental issues are presented in the textual part of the textbook.The analysis of the pictorial material was also included to gain insight into what type of pictorial material appears in the textbooks and what types of pictorial material are most frequently presented.
Particular attention was paid to the quality and clarity of the pictorial material and whether they were correctly placed on the page of the textbook so that they complemented the text and enabled students to better understand the material.In addition, to what extent is pictorial material in the different textbooks dealing with environmental content, and the consequences of reckless environmental behaviour were investigated.
According to the research problem, the following research questions were stated: 1) What are the differences between the learning objectives of the old and the current science curriculum in terms of environmental concepts and 2) What are the general and environmental characteristics of the textual and pictorial materials in the selected science textbooks in Grades 6 and 7 of primary school.

Method
The present study is based on a quantitative research approach; a descriptive, non-experimental educational research method was used.The criteria were developed on the basis of literature that presents criteria for the textbook analysis (Devetak & Vogrinc, 2013) and adapts them for Slovenian science textbooks/curricula.The criteria were used to analyse and compare the old and current 6 th -and 7 th -grade Slovenian science curricula for primary schools and to analyse and compare 6 th -and 7 th -grade science textbooks in Slovenian primary schools.

Sample
Four science textbooks for the 6 th grade and four science textbooks for the 7 th grade of primary school were analysed (Tables 1 and 2).Only textbooks available for students in the current school year (2023/24) and from a publisher that only issues textbooks for Grades 6 and 7 were analysed.In addition, the old curriculum (valid before the 2010/2011 school year) and the current curriculum (which replaced the old curriculum in the 2011/2012 school year and is still available for students in the current school year) for science in Grades 6 and 7 of primary school were analysed.

Table 1
The list of analysed sixth-grade science textbooks.

Instrument
The documents (textbooks and national curriculum) were analysed using the rubric developed for the purposes of this study and by adapting some of the criteria developed for textbooks, pictorial and textual materials (Devetak et al., 2010;Devetak & Vogrinc, 2013).
The rubric for the general and textual analysis contains basic information about textbooks, such as the number of pages, the number of chapters, and the number of pages in each chapter.Regarding textual analysis, specific didactic elements of the textbook were examined, such as explanations, instructions for experiments, summaries, explanations of new concepts, the activities in the workbook, introductory motivation, and tasks between the text and at the end of each chapter.The rubric for the textbooks' pictorial analysis sections was divided into two parts: 1) pictorial material Type I and 2) pictorial material Type II.Type I includes realistic images (drawings) and conventional images (graphs, diagrams, sketches, schematics, maps, and other presentations).Type II includes macroscopic-level images (drawings or photographs depicting a phenomenon or process, e.g., an experiment), submicroscopic images, and symbolic images.All the pictorial and textual material was also analysed in terms of environmental content, taking into account the framework of topics included in the national curriculum.

Research design
According to the rubrics developed for the general, textual, and pictorial elements in the textbooks, which follow the framework of the environmental content presented in the national science curriculum, the coding process was carried out by two independent persons.To ensure high reliability of the categorisation, two researchers (the two authors of this article) independently evaluated the textbooks using the coding table, resulting in an overall reliability of 96%.Both evaluations were then compared at the points where differences occurred, and after consideration, the more appropriate evaluation was chosen.

Results
The first part of the results shows the comparison between the old and the current national science curriculum in terms of environmental concepts, followed by general data for a comparison between textbooks (Tables 3 and 4).The second part of the results presents the analysis of the textbooks in terms of environmental content.

Environmental contents in the science curriculum (old and current)
The old science curriculum for the 6 th and 7 th grades of primary school was valid until 2011 when the then-responsible ministry (Ministry of Education and Sports) renewed the science curriculum.The number of lessons (one lesson is 45 minutes) for science in each grade remained the same, so students attended 70 lessons of science in Grade 6 and 105 lessons of science in Grade 7 throughout the school year: a total of 175 lessons of science in two school years.The old and current curricula differ in the scope of content (see Table 3).The old curriculum included a definition of the subject describing its place in primary education, the philosophy and nature of the subject, and the general and operational objectives presented.It also included activities, content, concepts and cross-curricular links, specific didactical recommendations, and the general proposals for knowledge assessment (i.e., a knowledge catalogue indicating the basic and minimum knowledge standards).The current curriculum also contains a definition of the subject, the general objectives, the operational objectives, and the content describing the science procedures and skills, as well as the thematic sets.It includes a section on the knowledge standards, which also describes the science procedures and skills and the thematic sets and makes some assessment suggestions for teachers.At the very end of the curriculum is the Didactic Recommendations section, which suggests teaching methods and approaches, guidelines for planning and implementing student activities, individualisation and differentiation, aspects, and cross-curricular links for each specific topic.
The old 6 th -grade science curriculum is much more clearly organised and defines the topics of the subject more precisely than the current one, which only covers more general topics and allows teachers to choose more specific contextual approaches to teach the concepts (e.g., environmental topics).
Nevertheless, the presentation of environmental content in both curricula is rather scarce or non-existent.In the sixth grade, students learn how they can contribute to the protection of the environment through appropriate behaviour, become aware of the significant influence of each individual on the environment, learn that the mining and processing of energy and other natural resources affect the environment, learn about the importance of efficient energy use, learn about the problems of scarcity and overuse of natural resources, water, raw materials and fuels, and become aware of the need to use these resources sparingly.In the seventh grade, students learn about the effects and consequences of fertilisation and the use of pesticides in agriculture on the pollution of groundwater, learn that the concentration of pollutants in water, air and soil can increase due to natural causes and human activities, which has a negative impact on organisms, learn about the main causes of pollution of water, groundwater, air and soil, learn about the main pollutants and the consequences of their effects on organisms and the environment, as well as the possibilities and measures to reduce and prevent pollution.They also learn about the effects of different types of transportation and communication on the environment and the causes of the increase in emissions and the associated global warming, which is reflected in climate change and terrestrial and aquatic ecosystems.
In the old science curriculum for 6 th grade, there are no learning objectives that relate directly to environmental content.Some teaching and learning suggestions for teachers that relate to environmental content can be found in the chapter Didactic Recommendations.The current curriculum contains the chapter Human Impact on the Environment with eight learning objectives directly related to environmental content.This corresponds to 8.6% of all learning objectives in the 6 th grade (Table 3).

Table 3
Comparison between the old and current 6 th -grade science curriculum in terms of topics and learning objectives related to environmental content and objectives for the topics defined by the national science curriculum.The old 7 th -grade science curriculum is much more precisely defined in terms of specific topics than the current one (Table 4).In contrast to the 6 thgrade science curriculum, both the old and the current 7 th -grade curriculum contain learning objectives that are directly related to environmental content.In the old curriculum, there are four (3.7%) learning objectives in different subject areas, while in the current curriculum, eleven learning objectives appear in the Human Impact on the Environment section, which accounts for 11% of all learning objectives in the 7 th grade.In the old curriculum, there was also a section on didactic recommendations in which some environmentally relevant content could be found but which must be included by the teachers in the relevant topics.

Table 4
Comparison between the old and current 7 th -grade science curricula in terms of content sections/learning topics and learning objectives related to environmental content and all objectives for the topics defined in the national science curriculum.

Environmental content of textbooks
The structure of the 6 th -grade textbooks published by different publishers varies considerably (Table 5).On average, the textbooks have 116 pages.The textbooks also have a different number of chapters.The textbook DZS/6 has the most chapters (9) and a maximum number of pages.The M/6 textbook has the fewest chapters (4 chapters), but the chapters are the longest on average (23 pages per chapter on average), and they present a broader range of concepts covering a given topic.The textbooks contain chapters with very different headings.The textbooks also differ in the number of pages per chapter.On average, the textbook NA/6 has the fewest pages per chapter (15 pages).Textbooks for 7th grade have an average of 169 pages.The textbooks also differ in the number of chapters, the headings, and the number of pages in each chapter.The textbook DZS/7 has the highest number of chapters (11 chapters).Other textbooks, R/7 and M/7 with 4 and NA/7 with 5 chapters, present science concepts very broadly in their chapters with more general headings.The chapters also differ in terms of the number of pages.The textbook NA/7 has the highest average number of pages per chapter (43 pages per chapter), followed by the textbook M/7 (36 pages per chapter) and the textbook R/7 (35 pages per chapter).The textbook with the lowest average number of pages per chapter is DZS/7 (16 pages per chapter).Regarding the pictorial material in the 6 th -grade textbooks, textbook M/6 contains the fewest pictorial material of Type I and Type II (377 images), while most pictorial material of Type I and Type II can be found in textbook R/6 (450) (Table 7).Most pictorial material comprises realistic images, followed by conventional images, macroscopic images, and sub-microscopic images of science phenomena.There are no symbolic images in any of the 6 th -grade textbooks examined.The textbook M/6 contains the highest percentage of realistic images related to environmental content (2.4%), followed by textbooks DZS/6 (2.3%) and NA/6 (1.2%).The lowest proportion of realistic images associated with environmental content is found in the textbook R/6 (0.6%).Conventional images associated with environmental content are only found in the textbook DZS/6 (1.5%).None of the 6 th -grade textbooks analysed contain macroscopic images and sub-microscopic images associated with environmental content.Of all the 6 th -grade textbooks analysed, the textbook DZS/6 has the highest percentage of pictorial material Type I and Type II related to environmental content (2.0%), while the lowest percentage of pictorial material Type I and Type II in connection with environmental content is in the textbook R/6 (0.4%).Although the textbooks for the 7 th grade contain a large amount of pictorial material, they differ significantly in the amount of pictorial material of Type I and Type II.As expected, realistic images make up the majority of the pictorial material in all the textbooks analysed, followed by conventional images, macroscopic images, and sub-microscopic images of science phenomena (Table 8).Symbolic images are only present in textbooks DZS/7, NA/7 and R/6.The images are of high quality and complement the textual material in the textbooks.The textbook NA/7 contains the most images (532 images), followed by M/7 (523 images) and R/7 (357 images), while the fewest images can be found in the textbook DZS/7 (350 images).Textbook R/7 contains the most realistic images associated with environmental content (2.5%), while the lowest number of realistic images associated with environmental content is found in textbook DZS/7 (0.4%).Only the textbooks DZS/7 and R/7 contain conventional images related to environmental content.None of the textbooks examined for 7 th grade contain macroscopic images, sub-microscopic images, or symbolic images related to environmental content.Of all the 7 th -grade textbooks analysed, R/7 has the highest percentage of pictorial material of Types I and II related to environmental content (2.0%), while the two textbooks, DZS/7 and M/7 have the lowest percentage of pictorial material of Types I and II related to environmental content (0.6%).Table 9 shows the results of the analysis of the textual material, such as explanations, instructions for experiments, interesting facts, summaries, explanations of new concepts, activities in the notebook, motivational content, didactic components, and tasks which are directly related to environmental content in each of the 6 th -grade textbooks studied.
The most textual material related to environmental content is found in textbook M/6 (9.4% of the total textual material), followed by textbook DZS/6 (5.4%) and NA/6 (4.3%).The lowest percentage of textual material relating to environmental content is included in textbook R/6 (2.7%).Summaries of the most important concepts can be found at the end of the chapters in all textbooks.
Tasks relating to the environmental content can only be found in the textbooks DZS/6, R/6, and M/6; the textbook R/6 contains the highest proportion of tasks relating to the environmental content (21.7%), followed by M/6 (16%) and DZS/6 (2%).Tasks for the students can be found at the end of the respective chapter (DZS/6, R/6, and M/6) and in the text (DZS/6, R/6, and M/6).
The textbook R/6 also contains a checkbox for the integration of the students' knowledge, which is designed like an interdisciplinary textbook.The Activities in the notebook, in which students are encouraged to continue the learning process in the corresponding notebook, are not included in the textbooks studied.Additional interpretations of new concepts are presented in the

Tm4
The number of summaries related to environmental content/number of all summaries.

Tm5
The number of explanations of new concepts related to environmental content/number of all explanations of new concepts.

Tm6
Number of activities in the notebook related to environmental content/number of all activities in the notebook.

Tm7
Number of motivating content related to environmental content/number of all motivating content.
Tmsum The total number of didactic components related to environmental content.

T1
The number of tasks in the text that are linked to environmental content/number of all tasks in the text.

T2
The number of tasks at the end of the chapters that are linked to environmental content/number of all tasks at the end of the chapters.
Tsum The total number of tasks associated with environmental content / the total number of tasks.
textbooks DZS/6 and R/6.All textbooks, with the exception of the textbook NA/6, contain an introductory text to arouse the students' interest.Other textbooks contain further specific sections, such as: in NA/6 the chapter Do it yourself, in DZS/6 a part entitled Some instructions on first aid in case of injuries and Optional knowledge, and in R/6 the chapters For the curious, Connect the knowledge and Key ideas and knowledge.
In addition to the textual and pictorial elements of the textbook, all of the 6 th -grade textbooks examined contain a section entitled Instructions for Experimental Work and Explanations and Interesting Facts.
Table 10 shows the analysis of the textual material in relation to environmental content in each 7 th -grade textbook.The textbooks analysed differ in terms of textual material and tasks related to environmental content.
The highest percentage of textual material related to environmental content was found in textbook M/7 (6.5%) and the lowest in textbook NA/7 (4.6%).Textbook M/7 contains the most explanations of environmental content (14.3%), and textbook R/7 contains the least (5.2%).The textbook R/7 contains the highest percentage of interesting facts (14.3%) and summaries (8.7%) related to environmental content.
Tasks relating to the environmental content can be found in all of the 7 th -grade textbooks examined.The textbook R/7 contains the highest proportion of tasks on environmental content (12%, most tasks are found between the text and at the end of each chapter), followed by NA/7 (4.8%), M/7 (4.2%) and DZS/7 (3.5%).
Environmental content is present in all textbooks analysed, but judging by the results of the analysis, this topic is insufficiently presented.All textbooks analysed contain explanations of new concepts, instructions for experiments, interesting facts, summaries, and introductory motivation at the beginning of each chapter.None of the textbooks contain the Activities in the notebook section.The textbooks DZS/7, R/7 and M/7 also contain tasks for students between the text and tasks at the end of each chapter.The textbook R/7 contains sections such as Health tips, For the curious, You can also read, and Protecting nature.

Discussion
This study aimed to determine what learning objectives relating to environmental content are included in the old and current science curriculum for Grades 6 and 7 and whether the science textbooks for those grades offer students opportunities to develop sustainable development competencies in relation to environmental content.
The old Grade 6 curriculum does not contain any learning objectives that relate directly to environmental content, while the old Grade 7 curriculum contains some of the learning objectives that relate to environmental content.In the science curriculum for Grades 6 and 7, there is a chapter on the impact of humans on the environment.The mentioned chapter contains eight learning objectives related to environmental content.These eight learning objectives account for only 8.6% of the learning objectives directly related to environmental content, compared to all 93 learning objectives in the Grade 6 curriculum.It can be seen that the curriculum has changed to such an extent that the current curriculum contains learning objectives that are directly linked to the development of students' environmental knowledge, whereas there were no such objectives in the old curriculum.
In the current Grade 7 curriculum, eleven learning objectives are listed in the chapter on human impact on the environment.At the level of all learning objectives in the current Grade 7 science curriculum, these eleven learning objectives account for 11% of all (100) learning objectives of that grade.Although there are not many learning objectives related to environmental content in the current curriculum, it can be concluded that the reform of the curriculum in 2011 has favoured environmental content and that appropriate implementation in the school setting promotes the development of environmental competences to some extent.
In summary, it is important to mention that in the renewed science curriculum in both grades, which will be the result of the current curriculum reform (see above), a significant increase in learning objectives for sustainable development should be integrated into different topics of the curriculum in order to fulfil the criterion that any curriculum should develop students' competences to actively participate in sustainable development activities as adult critical citizens.This is also important because, according to our findings, the current textbooks available to students lack direct implementation of scienceoriented sustainable development goals such as natural resource management, climate change, water-related issues, marine issues, biodiversity and ecosystems, circular economy, environmentally sound management of chemicals and waste, and many other topics.For this reason, it is recommended that the renewed curriculum be introduced in the 2026/27 school year, and the corresponding textbooks should more clearly include the implementation of the science-oriented sustainable development goals that are currently missing.
In line with our findings, some other studies (Lane & Wilke, 1994;Ernst, 2007Ernst, , 2009;;Fraser et al., 2015;Ashmann & Franzen, 2017) reported that although it is possible to find content in the curriculum that could promote the development of specific environmental competences among students, and they also emphasised that there are problems among teachers to teach environmental content.Other barriers include lack of training or opportunities for ongoing professional development, lack of technical support, safety concerns, teachers' responsibility for learning outside the classroom, lack of resources, lack of interest and support from local partners, and lack of support from parents (Rebolj & Devetak, 2012).
After analysing selected science textbooks for Grades 6 and 7, it can be concluded that the textbooks differ in terms of the number of pages and chapters, the number of pages per chapter, the chapter headings (although they deal with similar topics) and the amount of pictorial material that relates directly to the environmental content.Realistic images predominate in all textbooks, followed by conventional images and macroscopic images.Moreover, all textbooks include images because visualisation plays a very important role in the comprehension of science content (Bunce & Gabel, 2002;Dimopoulos et al., 2003), and these images are appropriate with regard to the cognitive development of the students and the type of content presented.Images that are presented vividly and placed in the right context can have a major impact on the development of environmental competences in both children and adults, as they highlight the state of the environment and, ultimately, the consequences of pollution.Therefore, it makes sense that the number of visuals in textbooks showing environmental problems and impacts should increase, as this should have a positive impact on a more positive attitude towards the environment (Ahmad et al., 2015;Chen, 2017).Although all the textbooks studied contain pictorial material directly related to environmental content, according to Paivio's theory (1991), there are not enough images to promote the development of environmental values in students through visual channels.
The textbooks studied also differ in terms of the textual material that presents environmental content.Our findings show that the amount of textual material in textbooks is increasing in favour of environmental content.This suggests that there is some environmental content in 6 th -and 7 th -grade science textbooks that are consistent with the learning goals of the curriculum but that some sustainability content is still missing (e.g., local and global content on protecting, restoring and promoting the sustainable use of terrestrial ecosystems, sustainable management of forests, halting and reversing land degradation and halting biodiversity loss, reducing death and diseases from hazardous chemicals, and air, water and soil pollution, strengthening resilience and capacity to adapt to climate-related risks and natural disasters, energy consumption, waste generation, public health threats, poverty, social exclusion, natural resource management, biodiversity loss and land use, etc.) and should be part of the new textbooks developed by publishers in the future.For this reason, the curriculum reform currently underway in Slovenia should thoroughly consider the integration of science-oriented sustainable development into the science curriculum in Grades 6 and 7 of primary school.
Overall, it has been proven that science is not one of the most popular school subjects among students (Grubelnik, 2011), but at the same time, the data show that fewer and fewer students are choosing to study science (Šorgo et al., 2018).Nevertheless, the data from TIMSS and PISA show that Slovenian students achieve better results on average in science knowledge tests than students in other participating countries (Japelj Pavešić et al., 2012;Štraus et al., 2007) and this could also be reflected by the use of quality textbooks in schools.

Conclusion
The results of the analysis of science Grade 6 and 7 curricula and textbooks give us an insight into the state of environmental education in Slovenia.From the results, guidelines for better and stronger integration of environmental content in textbooks and curricula could be derived for the renewal of curriculum in the framework of the Recovery and Resilience Plan.
The results of this study can influence teachers' decisions when choosing a textbook, as they can draw attention to important didactic components of textbooks, for example, the textbook by DZS, which contains various didactic elements that define a quality textbook according to selected criteria.At the same time, the survey revealed some inconsistencies in the textbooks that teachers should be aware of in order to supplement their lessons with additional teaching material to achieve the learning objectives.These findings can also help textbook authors, editors, and publishers as they can significantly improve the didactic value of existing textbooks in future editions.It is also important that authors and publishers include appropriate pictorial and textual elements in future textbooks that will be developed after the introduction of the new curriculum in Slovenian schools at the beginning of the 2026/27 school year in order to improve the development of students' environmental competences.
Considering the analysis presented in this paper, the limitation of this study is the lack of an in-depth content analysis of the environmental textual and pictorial elements of the specific textbooks.This should be done in the future textbooks that will be published after the renewal of the science curriculum in 2026.It is important to emphasise that an examination of curricula and related textbooks is possible, focusing on subjects such as home economics, biology, chemistry, physics, and geography.Such an analysis could provide a more comprehensive overview of the environmental competencies promoted at the lower secondary level.It is also recommended to investigate how Slovenian teachers and students use textbooks in science classrooms and how much knowledge they gain by using textbooks in the future, regardless of whether they are classic or digital books, such as e-textbooks, as the development of digital competences is as important as that of sustainability, according to the recommendations of the EU commission (Ferrari & Punie, 2013).

Biographical note
Matej Vošnjak, PhD, is a teaching assistant and researcher at the Faculty of Education, University of Ljubljana.He completed his PhD in Biosciences, scientific field horticulture, at the University of Ljubljana, Biotechnical Faculty.His research focuses on education for sustainable development, STEAM education, contextual approaches in science education, and projects dealing with research issues related to environmental sustainability.He is involved in several national and international projects dealing with the sustainable development and green transition of learners, adults, and professionals in the education system.Neva Rebolj, PhD, is a teacher at the Secondary School of Nursing in Ljubljana.Her research interests include teaching and learning science, solving science problems, the role of didactic aids and materials in learning and understanding science, and developing environmental literacy among pupils and students.Iztok Devetak, PhD, is Professor of Chemical Education at University of Ljubljana, Faculty of Education, Slovenia.His research focuses on how students, from elementary school to university, learn chemistry at three levels of chemical concepts, how chemistry in context and active learning approaches stimulate chemistry learning, using eye-tracking technology in explaining science learning, aspects of environmental chemistry education, developing teachers' health-managing competences etc.He was a Fulbright scholar in 2009.He is a Vice-chair for Eastern Europe of EuChemS DivChemEd from 2019, Chair of Chemical Education Division in Slovenian Chemical Society, Editor-in-Chief of the SCOPUS-indexed CEPS Journal, and editorial board member of respected journals.

Table 2
The list of analysed seventh-grade science textbooks.

Table 5
Number of pages, number of chapters and chapter headings in analysed 6 th -grade textbooks.

Table 6
Number of pages, number of chapters and chapter headings in analysed 7 th -grade textbooks.

Table 7
Analysis of pictorial material type I and type II in sixth-grade textbooks.CI Number of conventional images (graph, diagram, drawing, diagram, model of a molecule) associated with environmental content / Number of all conventional images (%).MI Number of macroscopic images (photograph of an experiment or phenomenon) associated with environmental content / Number of all macroscopic images (%).SuI Number of sub-microscopic images associated with environmental content / Number of all submicroscopic images (%).SyI Number of symbolic images associated with environmental content / Number of all symbolic images (%).TP Number of pictorial material Type I and Type II associated with environmental content/ Total pictorial material Type I and Type II (%)

Table 8
Analysis of Type I and Type II pictorial material in 7 th -grade textbooks.CI Number of conventional images (graph, diagram, drawing, diagram, model of a molecule) associated with environmental content / Number of all conventional images (%).MI Number of macroscopic images (photograph of an experiment or phenomenon) associated with environmental content / Number of all macroscopic images (%).SuI Number of sub-microscopic images associated with environmental content / Number of all submicroscopic images (%).SyI Number of symbolic images associated with environmental content / Number of all symbolic images (%).TP Number of pictorial material of Type I and Type II associated with environmental content/ Total pictorial material type I and type II (%)

Table 9
Analysis of textual material and tasks in sixth-grade textbooks.

Table 10
Analysis of textual material and tasks in seventh-grade textbooks.