The implementation of practical work in chemistry, along with the principles of green chemistry and sustainable chemistry, in Portugal

1.1 Chemistry is an experimental science

Chemistry is an experimental science that fundamentally depends on experimentation, focusing on the properties and transformations of matter. Key aspects include empirical foundations such as laboratory experiments, advances in instrumental techniques (such as spectroscopy and chromatography), and new technologies (which allow chemists to investigate substances at molecular and atomic levels). The application of theoretical frameworks is also essential (experimental chemistry validates models like quantum chemistry and thermodynamics by reproducing predicted outcomes under controlled conditions, thereby enhancing understanding of chemistry), as well as the employment of the scientific method (which involves hypothesis-driven research encompassing observation, experimentation, data analysis, and conclusion), and reproducibility (experiments should produce consistent results when conducted under similar conditions). Considering these characteristics, the laboratory (a space where conditions can be controlled, variables manipulated, and the scientific method applied) is the ideal environment for the development of chemistry (the creation of new knowledge, innovation in approaches, and advancements in technology and equipment). Extending this concept to chemistry education, the school laboratory becomes a privileged space for enhancing students’ knowledge and cognition, and for developing skills related to the progress of chemistry as a science and its integral role in chemical education. In this context, teachers incorporate laboratory work as it mirrors scientific methods. Chemistry is a practical subject with four main components: the laboratory component (procedural, epistemic, attitudinal, and knowledge-based), reasoning (solving problems, critical thinking, and scientific skills), a conceptual component, and finally, a communication component (reading, writing, and oral skills). Science education emphasises the importance of laboratory work as the primary means in the (re)construction of students’ ideas, to identify prior misconceptions, generate cognitive conflicts, and facilitate the application or evaluation of concepts. Teachers perceive laboratory activities as an inherent part of science instruction, often treating them as a separate, stand-alone component. ^{1 , 2} However, it is not merely the amount of work that matters, but rather the quality of that work, which justifies the time, effort, and expense involved in organising and conducting laboratory activities in science education.

1.2 Practical work, green chemistry education and sustainability chemistry education

In 2015, the 17 Sustainable Development Goals (SDGs) were adopted by all United Nations Member States, emphasising the importance of achieving sustainable and green chemistry objectives. After that, the educational systems incorporated these goals as pillars of a future society that not only focuses on human well-being but also on environmental well-being. Chemistry educators and curriculum developers disseminated these goals at the school level, so in recent decades, practical work in chemistry has incorporated the values and principles of sustainability and green chemistry. ^{3 , 4 , 5 , 6 , 7 , 8} They perceive that the incorporation of green and sustainable roles by the teacher, during the implementation of laboratory work (when implementing green activities, microscale activities, or changing reactants to more eco-friendly ones), plays a pivotal role in education for implementing greener and sustainable practices ^{6 , 9 , 10} and developing sustainable behaviours, Figure 1.

Figure 1:

In the educational context, work in the school laboratory is a privileged space for the development of sustainable chemistry. It represents the first step in chemistry education, connecting society — through informed decisions supported by scientific literacy — with the principles of green chemistry, which bridge industry, development, and innovation, as well as environmental issues that affect the health of the planet. These three pillars (society, green chemistry, and environment) provide the foundation for the development of education in sustainable chemistry, rooted in ‘green’ school laboratory practices and System thinking methodology, that will foster conscious attitudes and actions in the future, leading to the implementation of sustainable chemistry practices.

The types of laboratory activities endorsed by different curricula are influenced by their authors (curriculum developers), ^{11 , 12 , 13} and teacher practices. ^{14 , 15} There are six approaches to organising and conducting laboratory activities in the classroom ^{16 , 17} depending on the goals, and usually the syllabus proposes structured laboratory activities that yield predetermined answers. ¹⁸

Laboratory work can help link theory to practice, promote motivation, stimulate their interest in learning science, endorse the acquisition of laboratory skills and techniques, fundamental procedural knowledge, and enhance the understanding of conceptual knowledge (concepts, principles, laws, and theories), but also help develop scientific attitudes such as rigour, persistence, reasoning, critical thinking, creativity, objectivity, curiosity, responsibility, and cooperation ^{3 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29} (teachers’ primary objective is to help students understand how scientific theories are applied in real-world scenarios). To achieve this goal, ²⁸ students need to focus on three key areas: learning science to gain theoretical and conceptual knowledge, learning about science to understand its nature and methods, and practising science to develop technical skills. Furthermore, engaging in laboratory activities enhances critical thinking and problem-solving skills, allowing students to apply the scientific method through trial and error. It also improves scientific thinking by familiarising students with the methods and processes of science inquiry. ^{3 , 30 , 31 , 32 , 33 , 34} It can inspire curiosity and bolster personal development by promoting social competencies through collaborative activities. Lastly, laboratory work is grounded in active learning: ^{23 , 24 , 31 , 32 , 33 , 35} it transforms students into active participants by allowing them to experiment, manipulate materials, and directly engage with scientific phenomena. In these classes, teachers are encouraged to adopt a student-centred approach, ^{28 , 36} serving as role models in validating claims, helping students understand the nature of knowledge, and using inquiry-based learning strategies. As Katchevich, Mamlok-Naaman, and Hofstein ²⁵ (2013) stated, ”Learning science in a laboratory (…) provides an opportunity to learn science by doing science: hands-on as well as minds-on science” (p. 317). This implies empowering students to formulate arguments through reasoning and critique in a scientific context. Working collaboratively and cooperatively ^{24 , 25 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38} in small groups enables students to engage in debates, where their arguments can be supported or contested by peers, providing an argumentative and interactive learning environment. Throughout these discussions, ^{31 , 32 , 33} often guided or triggered by the teacher (teachers should maintain an active role while conducting these activities, as it can significantly impact student reflection and learning ^{18 , 21 , 22 , 31 , 32 , 33} ), students construct individual and collective knowledge through peer instruction. Assessments ^{19 , 37} should be adopted to practices and go beyond traditional written tests to include opportunities for students to reflect on their learning processes. Laboratory work can help to disseminate green chemistry concepts and promote sustainable chemistry.

Green Chemistry can be defined as an approach to chemistry that requires chemical synthesis generating less waste, with less energy and more safety. ³⁹ It implies cleaner processes, safer products, the use of green energy and involves 12 principles. ⁴⁰ As Hjeresen, Schutt and Boese (2018) ⁴¹ refer, green chemistry “encompasses all aspects and types of chemical processes that reduce negative impact on human health and the environment “(p.1543). It incorporates the cycle of design, manufacturing/production/synthesis, efficiency of the process, product life, needed resources and environmental friendliness. ⁹ In this context, in the last two decades, the national chemistry curricula/syllabi in some countries have changed, as Green Chemistry was incorporated in Education. ^{5 , 39 , 42} As Wang, Li and He (2018) ⁷ stated, “Green chemistry education aims at incorporating information about green chemistry into chemical education, thus being called to design suitable options for all the broad educational areas – curriculum development, teaching, learning and outreach, from in-class activities to laboratory experiments to the dissemination of information to the public” (p.123).

Sustainable chemistry presents a broader perspective, differing from green chemistry. Sustainable chemistry can be defined as a “scientific concept that seeks to improve the efficiency with which natural resources are used to meet human needs for chemical products and services”. ^{8 , 10} It incorporates societal and environmental benefits, implying a holistic view of the process. ⁴³ The Sustainable Chemistry Education emerged based on the Systems thinking methodology and a whole view. ⁴⁴ It should be noted that although green chemistry, which is mainly focused on products, is a building block of Sustainable chemistry, it is not always sustainable (doesn´t consider the Environmental Sustainability, Social Sustainability, and Economic Sustainability, only the 12 principles). ⁹

Education for sustainability ⁴⁴ nurtures critical consciousness, fostering understanding of reality and a sense of implication, integrating respect for diversity, the environment, and resources. It requires knowledge of sustainable development, current challenges, analytical competencies, and critical thinking, enabling consideration of local to global and short-term to long-term perspectives and aims to develop a willingness to transform, intervene, and make informed decisions, requiring a change in attitudes, behaviours, and recognising each person as an effective change agent. ⁴⁴ The main path to implementing, developing, and disseminating sustainability cognition, thinking, and attitudes is to implement them during education. The school environment, life experiences, and teachers are worthy pieces and scaffolds of this change process. To implement this change, teachers must have a deep knowledge of the nature of science, green and sustainable chemistry, understand the rules of practical work (laboratory, experimental, and field work), and the main goals of doing it. ³

1.3 Teachers’ conception and attitudes toward laboratory work and green chemistry

Teachers possess various conceptions – structures that may be conscious or unconscious – that comprise beliefs, meanings, rules, concepts, mental images, preferences, thoughts, and perspectives related to the teaching and learning of sciences. Research has demonstrated ^{1 , 45 , 46 , 47 , 48 , 49 , 50} that these conceptions significantly influence their instructional practices and shape how teachers perceive the world and organise their thoughts, functioning as personal perspectives on the realities they analyse. The importance of these conceptions lies in their ability to influence teachers’ behaviours and actions ^{1 , 38 , 49 , 50 , 51 , 52} as they shape how teachers understand the curriculum, teaching methods, and learning processes, impacting their interpretation of syllabus goals and the practices, namely regarding the use of laboratory activities in the classroom. Teachers’ conceptions about the nature of scientific knowledge (how knowledge is represented and how new knowledge is acquired) also influence what they teach and how they teach in the classroom. Additionally, the conditions under which teachers work can also impact their practices. ⁵³ So, to change a teacher’s practices in the classroom, it is essential to transform their conceptions regarding the nature of the teaching and learning process and the school conditions.

Research indicates that misconceptions held by teachers about laboratory activities often influence their instructional practice. ^{1 , 45 , 46 , 47 , 48 , 49 , 50} This can result in the indiscriminate use of laboratory activities ⁵⁴ and a lack of clear connections between these activities and the underlying theoretical concepts. ⁵⁵ Moreover, studies examining teachers’ methodologies and perceptions suggest that laboratory activities are typically teacher-centred and mainly designed to empirically verify previously taught concepts. ^{14 , 56 , 57} Empirical evidence ⁵⁸ shows that teachers often present low-demand activities, which may explain the decline in student motivation towards laboratory activities as they progress through their education ⁵⁹ and may justify why many students see the laboratory only as a place for acquiring practical skills and reinforcing theoretical concepts discussed in lectures. ⁶⁰ Teachers feel that following established recipes/procedures or protocols is safer and more comfortable ^{61 , 62 , 63} because they are familiar with the common difficulties students face, understand the time required for each activity, have easy access to materials, and avoid the extra effort needed to find and develop diverse activities for the classroom. Research evidence ^{61 , 62 , 63} indicates that teachers also tend to avoid conducting laboratory work, which, from their perspective, is ineffective in the teaching and learning process.

In the survey titled “Teachers’ Objectives for Lab Work in Europe,” ^{63 , 64} data revealed that teachers expect laboratory work to enhance their students’ conceptual understanding. The primary purpose of this approach is encapsulated in the phrase “to link theory and practice.” Teachers believe that practical experience deepens theoretical comprehension and primarily view practice as a means to support theory. This perspective aligns with findings from a study by Ottander and Grelsson (2006), ⁶⁵ which indicated that while teachers’ goals for laboratory work were similar, they also emphasized the importance of stimulating interest and enjoyment, developing practical laboratory skills, confirming theoretical knowledge, and fostering social interaction. Many teachers tend to emphasise the hands-on aspects of laboratory work, believing that students need to perform procedures to enhance their learning, ^{66 , 67 , 68} but their value is significantly heightened when accompanied by cognitive reasoning and engagement in the activity, ^{31 , 32 , 33} rather than just handling equipment or materials (physically involved) without grasping their purpose or relevance. Moreover, for this learning process to be effective, students should also be emotionally invested (hearts-on), as positive affective involvement can enhance cognitive engagement, ⁶⁹ and identify the task as useful in the future, which increases students’ motivation to be involved in the task. ^{32 , 33} However, many teachers lack the methodological background to implement these activities effectively, ¹⁵ and consequently, practical work may lead students to adopt a surface approach to learning rather than encouraging a deeper understanding.

Teachers perceive themselves as mediators between students’ knowledge and the scientific concepts they are expected to learn, as well as facilitators in the construction of knowledge. ^{31 , 32 , 33 , 70 , 71 , 72} They are responsible for creating a classroom environment that encourages students to engage in activities, ^{31 , 49 , 73} articulate the problems that need to be addressed, and emphasise the primary objectives of the task, so that students fully grasp the questions at hand. Students should understand what they are seeking, formulate predictions, plan and execute experiments, draw conclusions, and reflect on the work undertaken. Additionally, teachers recognise that laboratory work begins well before entering the laboratory, ^{20 , 21 , 22 , 30 , 31 , 32 , 68} being important for them trigger the students’ initial work, clarifying the theme, discussing prior knowledge about the subject, promoting students’ researching information, planning the experiment, and identifying the quantities to be measured, along with the conditions, materials, and equipment to be used. ^{10 , 74 , 75 , 76 , 77} But teachers also use laboratory work ³⁷ for knowledge evaluation, assessing students’ understanding of scientific concepts and their capacity to apply them practically. Usually, they use worksheet-based laboratory tasks, which produce clear and correct answers, which may arise from teachers’ perception of lower risk for students who seek recognition for their efforts and fear failure in laboratory settings. ^{37 , 78 , 79}

In a study (2018), Malaysian teachers perceived that “green chemistry experiments embrace the cognitive, affective and psychomotor domains. The experiments resolved several challenges emerging from operating the traditional lab. The findings of this study suggest green chemistry possesses the potential to be integrated into mainstream chemistry education.”(p.113). ⁸⁰ These findings were corroborated by research conducted in Nigeria, with secondary school chemistry teachers. ⁸¹ It is important to highlight that teachers perceived that they should prioritise topics in green chemistry and sustainable chemistry that resonate with students’ interests and are relevant to their everyday lives, contributing to their education and nurturing responsible citizenship. ^{78 , 80 , 81 , 82 , 83 , 84} It’s important to note that teachers generally have a positive attitude toward including green chemistry in the curriculum. ^{78 , 79 , 85 , 86 , 87} Teachers propose that laboratory activities should be aligned with the principles of green and sustainable chemistry, which requires teachers to prioritise specific themes and questions that will guide their research plans. ^{61 , 62}

1.4 Study context and relevance

Several studies and reports ^{43 , 49 , 88 , 89} indicate a widespread trend among Portuguese teachers to retain conventional teaching practices in science that underscore the acquisition of terminology, facts, principles, and laws. Such practices are inconsistent with the goals of programs aimed at promoting scientific literacy. Martins (2009) ⁴⁹ inferred that Portuguese teachers may feel unprepared to adopt teaching practices that differ from those they encountered during their education process. In such settings, students adopt a passive role in their learning, resulting in a neglect of procedural and epistemological knowledge, as well as aspects of attitude, communication, and reasoning. This perspective is supported by research, ^{38 , 73 , 90 , 91 , 92 , 93 , 94 , 95 , 96} which notes that various factors can influence a teacher’s practice.

In the current Portuguese context, it has been observed that activities foster more meaningful learning when they are used to consolidate knowledge already introduced by the teacher. ⁹⁰ This is especially true for students with lower skill levels, as direct instruction has proven to be an effective teaching method. It helps to minimise extraneous cognitive load, enabling students to allocate greater resources from their working memory toward developing their understanding. ⁹⁰ But the requirements of contemporary Chemistry Portuguese Curricula ^{97 , 98} demand a shift in teaching practices, enabling students to take an active role in their education. Among the various methodologies proposed in the Portuguese Chemistry Syllabus, those grounded in scientific inquiry stand out. ^{90 , 91 , 92 , 93 , 94 , 95 , 96 , 97} These approaches are flexible, as they focus on questions formulated by the students and emphasise problem-solving, collaborative work, and the promotion of interdisciplinary projects and develop critical thinking skills, information analysis, communication, logical argument presentation, teamwork, as they promote the students’ engagement in diverse contexts. ^{38 , 90 , 91 , 92 , 93 , 94 , 95 , 96}

Over the past two decades, the implementation of mandatory laboratory activities in chemistry classes has gained significant attention from Portuguese policymakers. Schools have been equipped with the necessary materials and reagents to facilitate these activities. In the chemistry curriculum, teachers are allocated 1 h per week in middle school and 3 h per week in high school for conducting experimental and practical classes, typically with half the class size. Recently, a new curriculum was introduced (Order No. 6605-A/2021, dated July 6, by the Ministry of Education), which outlines the curricular guidelines for various aspects of curriculum development, including external evaluation. According to this syllabus, all students are required to enrol in chemistry from the 7th to the 9th grade (middle school). In high school, from the 10th to the 11th grade, chemistry is only available to students enrolled in Science and Technology courses. Notably, the concept of green chemistry is explicitly included only in the 11th grade curriculum, in the topic of “Quantitative aspects of chemical reactions” in the subject named “Física e Química A” (Physics and Chemistry A). The task associated with sustainability and green chemistry involves comparing chemical reactions from a green chemistry perspective, assessing their implications for social, economic, and environmental sustainability. Additionally, laboratory work related to this topic includes the synthesis of acetylsalicylic acid, focusing on aspects such as yield and the 12 Principles of Green Chemistry, namely Atom Economy (Essential Learning Outcomes). Since green chemistry and sustainable chemistry are not explicitly mentioned in middle school, it is crucial to have well-informed teachers who can effectively disseminate these important concepts.

In the last decade, there have been few research publications on Portuguese Chemical Education, particularly regarding laboratory work and even fewer regarding green chemistry implementation. Nowadays, schools are undergoing significant changes due to shifts in the teacher profile, influenced by a shortage of qualified teachers and the entry of professionals from other fields who provide instruction without needing formal teacher training or enrollment in professional development courses. Additionally, the curriculum is also changing. In this context, it is important to understand how laboratory work is being integrated into the Portuguese teachers’ practices and whether the principles of green chemistry and sustainable chemistry are being incorporated into it. Furthermore, this research aims to provide new insights into: a) how Portuguese chemistry teachers perceive the integration of sustainable and green chemistry into their laboratory classes; and b) to perceive whether Portuguese chemistry teachers continue to use teaching practices that are unsuitable for fostering students’ scientific literacy and sustainable and green values, or are adopting innovative practices with green laboratory activities as support.

2.1 Research design

In the present study, we have primarily utilised a quantitative methodology, employing a questionnaire for data collection. This approach facilitates a more systematic gathering of participants’ perceptions and representations regarding the topic under investigation, thereby justifying the use of a questionnaire given the size of the population to be surveyed (the survey was applied in many countries around the world).

2.2 Procedure and data collection tools

The IUPAC international survey – Green and Sustainable Chemistry Survey ^{99 , 100} was used, and data were collected through online dissemination all over the country, through chemistry teachers’ groups in social media, and the “Portuguese Association of Physics and Chemistry Teachers” and applied to the Portuguese in-service teachers of the Recruitment Group of Physics and Chemistry. It had three sections, the first referred to demographic data, the second to Chemistry practical activities, and the third to Green and sustainable chemistry practical activities. ¹⁰⁰ It had a set of closed-ended questions and some open-ended questions. The initial questionnaire, in English, was translated into Portuguese and adapted to the Portuguese Chemistry curriculum and the Portuguese teacher population’s academic qualifications. It was open for one year, from November 2023 to November 2024.

The survey’s aim was outlined at the beginning of it: “This survey is designed to gather information from high school teachers about chemistry practical activities that they use in lower secondary and upper secondary classes. We are interested in what types of activities teachers use, why they choose them, and whether activities relating to green chemistry and sustainability are being used.” ¹⁰⁰ During the survey, some definitions were provided to help teachers understand the authors’ point of view on practical activity, the purpose, green chemistry (https://www.acs.org/greenchemistry/principles/12-principles-of-green-chemistry.html), and sustainability (https://www.sustainablechemistrycatalyst.org/s/Defining-Sustainable-Chemistry-Report-Feb-2023.pdf).

2.3 Participants

A total of one hundred 78 teachers participated in the questionnaire; however, only 149 completed all three sections. This discrepancy can be attributed to the fact that some respondents teach Professional Courses (Courses that imply European Qualifications Framework from level 1 to 4 that are mainly geared towards the job market and not to pursuing studies in higher education), which have curricula distinct from those of Secondary Courses (whose principal aim is to pursue higher education level). Additionally, some teachers instruct Physics in the 12th grade or teach other subjects. In Portugal, for instance, teachers within the Physics and Chemistry Recruitment Group are allowed to teach both chemistry and physics, as well as related subjects (note that green chemistry is only explicit in the 11th grade in the subject named “Química e Física A”, and in other chemistry-related subjects, green chemistry is not explicit in the syllabus).

3.1 Characterisation of the respondent chemistry teacher population

The demographic characterisation of the respondent population was made. The teaching time of this population reflects the age of the teachers (Table 1).

A significant portion of the teachers surveyed have been teaching for over 16 years, with 52 % of the respondent population having between 16 and 30 years of experience, and 29 % had more than 30 years, which reflects the ageing demographics of the teaching workforce. Notably, this group of educators possesses higher academic qualifications; 7 % hold a doctorate (PhD), 35 % have attained a master’s degree, and 2 % have completed specialisation courses (see Table 2). Furthermore, the data presented in Table 2 reveal a diverse range of undergraduate study backgrounds among the teachers who instruct chemistry classes.

The current teaching workforce, despite an ageing demographic, is highly educated and qualified. The proportion of teachers holding a PhD in the sciences underscores the challenges faced in Portugal regarding careers in teaching or research within higher education. Similar trends have been observed across other scientific disciplines in Portugal, where educators frequently possess master’s degrees (two-year degree), doctorates (three- or four-year degree), and licenciaturas, which refer to 5-year degree programs predating the Bologna Process. It is important to note that before the Bologna Process, gaining entry into the teaching profession required a licenciatura (a Portuguese degree that entails 4 years of university study followed by one year of pre-service teacher training) or a Bachelor’s degree (a 3-year program), along with an additional year of qualifications at the university and another year of in-service training. Currently, under the Bologna Process, the requirements for entering the teaching career have been streamlined to necessitate only a Bachelor’s degree (3 years of university study) and a master’s degree in teaching (a 2-year program).

In this sample, some teachers had pre-service teacher qualifications during their bachelor’s (licenciatura) (58.5 %), but others had them during their teaching profession (33.1 %), while a few had no teacher qualification/formation (8.4 %) (Table 3). This data highlights the ongoing demand for professionals in the chemistry and physics fields, as well as the educational system’s willingness to integrate individuals from other science and engineering backgrounds into roles teaching chemistry and physics. It is noteworthy that these professionals often teach in middle and high (or secondary) schools despite lacking formal teacher training.

It is worth noting that during the pre-service teacher training, of the Chemistry or Physics teachers, before Bologna, pre-service teachers give classes (two classes) for one year with the accompaniment of a pedagogical supervisor (a teacher from the school) and scientific supervisors (teachers from the university in the Chemistry, Physics areas) (Ordinance n.° 649/78, Novembre 8), only then they had the degree, and could enter to the profession. After Bologna, the chemistry teachers’ course students only had to go for a few weeks to a middle or high school, and the rest of the formation was done in the University, as they had to complete a master’s degree in teaching chemistry and physics (Decree-Law n.° 79/2014, May 14). At this moment, the scarcity and reduction of the number of teachers in various areas of knowledge, namely in the Chemistry area, is triggering changes in the initial training of teachers and access to the teaching career. For now, in the Portuguese educational system, the number of teachers with their training and formation to become professional teachers in chemistry and physics is higher than the number of professionals who give classes without any training or formation in teaching chemistry.

3.2 Practical activities

Science laboratory activities can be seen as tools that allow indoor reproduction or simulation of natural facts and phenomena (or parts of them) through conventional laboratory equipment and reusable everyday materials that students and teachers handle to produce data. ^{10 , 31 , 32 , 33 , 68 , 102} In the present research, practical activity is “a chemical reaction, experiment, or demonstration conducted in the classroom or laboratory by students or a teacher; videos, simulations, and animations do not qualify as practical activities in this research”. ^{99 , 100} The identification of Portuguese teachers’ perspectives of science teaching and learning has been the target of several studies, conducted in Portugal, at the beginning of the twenty-first century, which aimed to characterise the perspectives of science teachers on the use of practical work, namely, laboratory work, ^{26 , 68} conception and implementation of laboratory work. ^{89 , 94 , 102} According to these studies, the conceptions about laboratory work usually implemented in science classes still seem to be under the traditional perspective (mainly demonstration, illustration, verification of the theory, and laboratory techniques), where the student continues to play a passive role in the teaching-learning process. It should be highlighted that teachers’ conceptions do not change due to the transformations occurring in education, tending to remain throughout their professional life unless they feel the need to change and innovate their practice. In this way, teachers must embrace a change in their conceptions and transform their teaching practices, fostering a teaching and learning environment focused on greater student involvement in the proposed activities, particularly laboratory work.

Results regarding collected data (Table 4) show that only one per cent of the teachers stated that students didn´t perform laboratory activities. 44 % of the teachers reported that their students had performed around once per month (approximately 9 per year). However, teachers are almost divided between a frequency of a few times per year (22 %) and around once per week (28 %). The 44 % of application of lab work may be justified by the requirement of the high school (secondary school) curricula of the subject Physics and Chemistry A, that teachers must propose/plan the curricula’s mandatory experiments that students must do (in 10th grade: 6 of Chemistry, and 7 of Physics; 11th grade: 5 Chemistry, and 6 Physics).

Comparing these results with other Portuguese studies, it can be stated that these data are similar to those obtained for Physics and Chemistry in the early twenty-first century. ⁵⁶ Moreover, when comparing the Curricula with the laboratory requirements, it can be argued that the syllabus mandates students perform more than one activity each month, regardless of grade level. In Portuguese schools, there is also a low use of laboratory work in middle school science classes ^{49 , 56} and when teachers do use it, they typically conduct demonstrations, verifications, or illustrations of previously taught theories. ³⁴

Results show that 47 % of teachers use simulations, 43 % provide students with data for analysis, and 47 % show videos of chemical reactions very often (once or more a week) (Table 4). This trend can be attributed to the fact that Portuguese textbooks are connected to materials available on Portuguese learning platforms. These resources include data sets, videos, simulations, quizzes, and audio guides. They are freely accessible for teachers to use in the classroom, and students can also use them at home. And this may explain the computer simulations usage (average score 3.01), the use of animations (average score 2.81), or “provide students with data to analyse or perform calculations” (average score 2.80).

In international studies, most of the time, the laboratory work developed in the classes is almost totally dominated by the contents, where students tend to be concerned with obtaining the ‘right answer’, developing little their abilities, connoting absence or inadequacy of the pre- and post-laboratory discussion, which according to Tamir (1991), ¹⁰³ Millar (2004) ¹⁰⁴ and Jokiranta (2014) ³⁰ is essential for give meaning to the activities to relate them to theoretical concepts. These aspects diminish the effectiveness of laboratory work conducted in schools.

Considering that the Laboratory tasks (experiments) can be categorised on the level of openness regarding the roles of students and teachers in the tasks, ^{105 , 106} the current findings suggest that practical activities primarily involve students through confirmatory hands-on approaches (typically the ones who are recommend in the Syllabus/Chemistry curriculum) (28 % once a week, and 44 % around one per months), while teachers engage in demonstrations (30 % once a week, and 34 % around one per months). However, it’s important to note that in Portugal, activities are not entirely open (although maybe executed by students), activities are structured around a specific procedure designed that is described in the textbook (and proposed in the Curriculum), with information to aid students in data analysis, with teachers typically being aware of the expected outcomes in advance. From the present data, it is not possible to perceive whether demonstrations include active interaction with students. If so, they can be considered a minds-on approach.

To ensure teachers fully grasp the significance of key factors when selecting chemistry practical activities for their classes, whether through demonstrations or student participation, they must assess the importance of each statement (Table 5). In this context, it is extremely important (49 %) or very important (43 %) for the teacher that “The practical activity helps students develop conceptual understanding/students can readily link their observations to current curriculum topic”. These findings are in line with previous international studies. ^{23 , 24 , 75 , 107 , 108 , 109} In the statement “Students have opportunities to develop critical thinking and problem-solving skills”, 58 % of the respondents’ teachers assigned extremely important, 34 % assigned very important. It is also interesting to see the importance given to reports or write protocols-42 % of the teachers assigned very important and 16 % extremely important. Although these tasks imply different involvement of the students, for instance, if it is a report of a “textbook procedure/receipt”, students’ work is almost only a copy, but if students create a protocol to achieve goals, and then they do a report, this task implies metacognition involvement and communication skills. ^{75 , 77 , 79 , 110 , 111} Traditional laboratory reports are useful for open-ended activities; they may be ineffective for structured worksheet-based tasks, where students often transcribe information and answers. ¹¹¹ This copying, as noted by Ellis, Taylor and Drury (2007), ⁹⁵ does not align with the advocacy for writing as a key part of learning science. As noted in the research published by Carlo and collaborators (2006), ⁷⁸ many students rely on various methods to find the right answer, with some opting for copying instead of engaging deeply with the material.

The results indicate that 49 % of teachers place extreme importance on developing procedural skills, which include motor skills, while 44 % consider them very important. They also emphasise the acquisition of scientific skills, such as observing, measuring, correctly using equipment like scales, understanding safety rules, and following procedures like titration (see Table 5). Regarding the statement “Students get the correct result/experiment always works,” only 6 % of the teacher respondents rated it as extremely important, 13 % as very important, 44 % as moderately important, 18 % as slightly important, and 16 % as not at all important. This finding may be attributed to the perception of some teachers who view laboratory work mainly as a way to confirm theoretical concepts or who feel uncomfortable addressing students’ incorrect results.

The significance attributed by teachers to motivation for laboratory work and student involvement is evident in their analysis of the statement, “Students like doing practical activities.” Here, 44 % of teachers consider it extremely important, while 42 % view it as very important. Similarly, regarding the statement, “Students behave better during practical sessions than if they are just listening and writing” 36 % deem it extremely important, and 45 % regard it as very important, highlighting the level of student engagement in lab activities. Furthermore, teamwork is highly valued by the responding teachers, with 34 % rating it as “very important” and 56 % as “extremely important.” Additionally, a significant proportion of teachers (42 %) consider it very important and 45 % extremely important that practical activities be safe, easy to set up, and equipped with all necessary materials. This reflects a strong emphasis on maintaining a safe classroom environment, which can be achieved through simple experiments that are easy to execute and interpret, yielding expected results, given that schools are equipped with the materials and reagents required for mandatory syllabus experiments and laboratory tasks.

An overview of the scores’ dimensions is in Table 6, highlighting the importance for teachers when they plan a practical activity. Higher score values on each scale reflect higher levels of the variable that the scale intends to measure. So, when the score values, on each scale, are higher than the average of the possible score obtained on that scale, this attribute is considered relevant. The scales have different maximum values, and to determine which scale was more relevant, the ratio (in percentage) of the average score obtained and the maximum value of each scale is presented in Table 6.

Looking at the average score, it is possible to see that teamwork is extremely relevant, and as the development of procedural skills for teachers. Metacognition, practicability and safety have the same relevance (84 %), and motivation is the least relevant (71 %). But the most important rule is the technique learning/performance (88 %) and teamwork (89 %). Our results show that the respondent teachers perceive the laboratory as a motivation prompt, as a promoter of learning laboratory skills and techniques, crucial to procedural knowledge, to promote the learning of scientific methodology, but also to develop scientific attitudes, including rigour, persistence, critical reasoning, divergent thinking, creativity, objectivity, curiosity, responsibility and cooperation. Although experimental work has these advantages, from the teacher’s point of view, a study with Portuguese students published in 2012 by Carvalho and collaborators ⁸⁵ found a noteworthy motivational impact on students, but significant learning was not visible at the conceptual level. Other studies with Portuguese students have argued that not only does it increase motivation but also enhances knowledge in chemistry and physics; nevertheless, laboratory work must be adapted to the new times and the evolving student profile. ^{31 , 32 , 33 , 34 , 90 , 94} Hodson ^{22 , 28} emphasised the importance of developing science education based on three main pillars: first, learning science, which focuses on acquiring and enhancing theoretical and conceptual knowledge; second, learning about science, aimed at fostering an understanding of the nature and methods of science; and third, doing science, which involves gaining technical knowledge in scientific research and problem-solving. Our findings suggest that the teachers surveyed are primarily focused on the aspect of learning science.

Teachers also had the opportunity to reflect on the other factors that could negatively impact their decision to do practical activities, by answering the following question: “What other factors are important to your choice of practical activities?” (Table 7). The factors assigned in the present research were also reported in international studies. ^{74 , 79 , 111}

It is also relevant in this research study to perceive what hinders the implementation of practical work, namely, the laboratory work and experimental work. To capture some light regarding it, a question was posed to the respondent teachers: “What factors prevent you from using chemistry practical activities more often in your class?” (Table 8). Half of the respondent teachers assert that the time is crucial not only to prepare all the apparatus and reagents, but also to complete the subject curriculum; the lack of resources may also hinder the application of practical work.

Some teachers had presented other obstacles. One referred to “The curriculum of the 12th grade is inadequate for the number of school schedules. We should have more teaching time (currently 3 h a week, 2 of which for practical activity), another (from the professional schools) referred “short module durations” and in the same sense others stat “Lack of time, very extensive curricular content and little teaching time to be able to reach all these contents.” and “Very extensive program” or “Extension of the programs/Syllabus”. Another factor assigned that enables the chemistry practical activities more often in class is “Inappropriate behaviour of students in experimental classes”, but also “High number of students per class”. The last motive was “lack of resources needed to carry out the laboratory’s activities”. Constraints like course length and pressure on teachers also play a role, contributing to the traditional models of science teaching that diminish the value of laboratory activities. These data are corroborated by other research, ^{74 , 78 , 79 , 111} where many teachers express concerns about the challenges they face when trying to incorporate laboratory activities into their lessons. They often cite issues such as the unavailability of laboratories, the absence of laboratory technicians, shortages of equipment or reagents, insufficient time, and students’ lack of interest in these activities. Other difficulties also include the lack of laboratory material for all students to carry out experiments (even if the work is done in a group), lack of space (sometimes the laboratory is not available), and the need for complying with the program and the excessive workload of students (in 11 grade and 12 grade students have national external examination), the poor training of teachers concerning this type of activity and the student evaluation process.

In a research study in Portugal ⁹⁴ regarding the implementation of laboratory activities in Chemistry (11th grade), Portuguese students reported that laboratory work is often seen as subordinate to other activities. ⁹⁴ This perception stems from poor time management and a lack of clear communication regarding evaluations from their teachers. Students expressed frustration over deviations from planned schedules, believing that improved time allocation could enhance their engagement in the subject. The study published by Bento (2016) ⁹⁴ highlights a disparity in report completion, affecting evaluations and reflecting the lack of meaningful learning experiences. Furthermore, the importance of learning scientific methodology is often overlooked, with laboratory work used more as a confirmatory resource rather than an effective learning tool. ^{90 , 94} While Portuguese students seek to take a more active role in their education (they express the desire to do more experimental activities in the laboratories and have a more active role), the overshadowing of laboratory classes by other tasks (like resolving exercises) is captured in other research concerning the use of laboratory activities, ⁹⁰ and it reveals the teacher’s conception of laboratory work, as a confirmatory task and not as a research task. ^{90 , 94}

3.3 Green chemistry and sustainable chemistry

Considering the IUPAC authors definition ^{99 , 100} of Green Chemistry (is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances) and Sustainable chemistry (is the development and application of chemicals, chemical processes, and products that improve how natural resources are used to meet the needs of current and future generations, without harmful impacts to humans and ecosystems), respondent teachers had to use a slide bar to answer the following question (0–100). “What percentage of the chemistry practical activities that you run involve green chemistry, or relate chemistry to sustainability?” The average response was 37.92 % (129 respondent teachers). These data reflect the lack of dissemination of the concepts of green chemistry and sustainability in the Portuguese curriculum, in the textbooks, and in teachers’ training professional development courses. Teachers implement laboratory tasks without considering the importance of being green (continue to do, for example, the plumb iodide precipitation) and sustainable (be aware of the residues produced).

Teachers also had to assign the importance of each of the following factors when selecting chemistry practical activities for their class (either demonstration or student-performed) (Table 9).

For 42 % of the respondent teachers, it is extremely important that “Students have opportunities to develop critical thinking and problem-solving skills related to green and sustainable chemistry”. 48 % of the respondents assigned “very important” regarding “Practicals are a way to introduce green chemistry and sustainability through a hands-on activity“, and 39 % assigned as very important the statement “Students find green chemistry and sustainability issues and topics engaging”, and also “Be practical activities proposed in the curriculum”. The average scores confirm that practical activities that develop critical thinking and help solve problems related to green chemistry and sustainability are the most relevant factors to choose them (average scores, 4.16), followed by their appearance in the curriculum (average score 3.84) and their versatility to simultaneously be hands-on activities (average score 3.81) that aim to foster green chemistry and sustainable chemistry values (average score 3.62).

Because green chemistry and Sustainable chemistry have appeared only in recent years in the Portuguese curriculum, and are only explicit in eleventh grade, it is relevant to perceive where teachers research or find their activities. To achieve this goal, they had to answer the following questions: “Where do you normally obtain your chemistry practical activities related to green chemistry and/or sustainable chemistry?” (Table 10).

Portuguese teachers must take courses throughout their careers to promote professional development, which allows them to advance in their teaching careers. These courses must be accredited by a Portuguese educational authority and applied by Teacher Training Centres. And this is assigned by the respondent teacher when 52 % selected “Learned during professional development, in training courses, after starting teaching career (in-service)”, the collaborative work and the communities of practice, also referred to indirectly when 33 % assigned “Learned from other teachers”. Twenty-nine per cent of the respondent teachers selected “Heard about at a conference” and “Read about in a magazine or online”. It is relevant to inform that Portuguese teachers have annual conferences, promoted by scientific societies (Physics, Chemistry, and others), institutions like “Ciência VIVA”, institutions linked to Universities or the Portuguese Physics and Chemistry teachers’ Association, and some patron (Belmiro de Azevedo Foundation, EDULOG). Teachers are active participants in meetings and conferences, as some present work done in schools. In these conferences, the exchange of experience and strategies helps overcome their constraints in their day-to-day life.

The resources (magazine or online information), named by 29 % of respondent teachers, regarding practical green chemistry and/or sustainable chemistry, were firstly “The Portuguese Chemical Society Magazine”, followed by “Revista elementar casa das ciências” (a Portuguese review, for teachers, of all natural sciences promoted Belmiro de Azevedo Foundation, EDULOG), textbooks, groups of physical and chemistry teachers, the Portuguese Association of Physics and Chemistry Teachers (APPFQ), Science buddies website and Google scholar. But also sites similar to ”MEL Science: Fun Science Kits & Experiments for Kids”, Science in School (the European journal of science teachers), Green Chemistry Journal, American Chemistry Society, Royal Society of Chemistry, Journal of Chemical Education, Portuguese publishers’ platforms (Aula digital and Escola virtual) and in course attendance. From these results, it can be inferred that some Portuguese teachers are involved in implementing green chemistry and sustainability in their classrooms, and that they actively pursue more information and experiments that can be framed in their teaching goals and be implemented in the laboratory.

It should be noted that the role of the teacher in teaching should be seen as a facilitator and promoter of success in their students’ learning. ^{1 , 55 , 79} To do this, teacher must reflect, plan and implement activities that allow the development of learning at the level of conceptual and procedural knowledge, that is, the teacher must identify the previous ideas of the students, to create an environment that encourages the student to build and communicate their points of view and then design student-centred activities that allow highlighting and doing involve these same learnings. ⁵⁷ Still, although respondent teachers can create a stimulating educational environment in the class, the activities/tasks proposed are usually from the curriculum or textbooks. This is supported when the teacher described three activities they propose to students; all the activities mentioned were included in the Portuguese Chemistry curriculum, particularly the synthesis of acetylsalicylic acid. Other teachers stated they carry out the activities on a microscale and use environmentally friendly reactions. It can be seen (Table 10) that 8 % of the respondent teachers design their practical activities.

At the end of the survey, teachers were asked about the importance of each statement regarding green chemistry and Sustainability enrichment in their training and curriculum (Table 11).

Between 82 % and 86 % of the respondent teachers assign very important or extremely important to “Attend teachers training courses on Sustainability” or “Attend training on Sustainable Chemistry and Green Chemistry”. These results suggest that teachers have a strong desire for the introduction and implementation of green and sustainable laboratory activities. Teachers consider that it is necessary to increase training (learning and teaching) regarding Sustainability, Sustainable Chemistry and green chemistry from middle school and high school to higher education schools. Teachers also consider relevant the implementation of tasks, for example, in DAC projects (Domains of curricular autonomy, interdisciplinary and transdisciplinary projects), on Sustainability, Sustainable Chemistry and Green Chemistry, to develop the scientific literacy of students. Some teachers reported that they have already implemented it in interdisciplinary projects. So, the implementation of green chemistry education goals is starting to disseminate through all the Portuguese curriculum from the 7th to 9th grades (middle school), continuing in the high school from 10th grade to 12th grade, slowly but firmly, as a silent wave promoted by the teachers in the classroom.

It should be noted that teachers in their daily life in schools face several challenges when implementing activities designed to develop students’ conceptual and procedural skills in science. As a result, many often avoid conducting laboratory work that lacks effectiveness in the teaching-learning process. But research ⁶³ also suggests that even though teachers may initially resist new approaches to laboratory activities, with appropriate training, they gradually overcome their reluctance and develop a willingness and motivation to implement these methods differently in everyday science classrooms.