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DOI: 10.1039/C6RP00158K (Paper) Chem. Educ. Res. Pract., 2016, 17, 1067-1080

Using the lens of pedagogical content knowledge for teaching the nature of science to portray novice chemistry teachers' transforming NOS in early years of teaching profession

Surayot Supprakob *a, Chatree Faikhamta a and Potjanart Suwanruji b
aKasetsart University, Faculty of Education, Bangkok, Thailand. E-mail: kimjihoon_tomoko@hotmail.com
bKasetsart University, Faculty of Science, Bangkok, Thailand

Received 18th July 2016 , Accepted 9th August 2016

First published on 9th August 2016

Abstract

Pedagogical content knowledge for teaching the nature of science (PCK for NOS) has attracted interest in recent decades. This study investigated the PCK for NOS of six novice chemistry teachers with various educational backgrounds. An interpretive case study was performed. Multiple data sources including classroom observations, field notes, semi-structured interviews, and teachers' artifacts were collected. The inductive process used to analyze data involved categorical aggregation, followed by a search for patterns and themes. The findings revealed that all participants had limited PCK for NOS in terms of all of its components. They had robust chemistry knowledge and expressed adequate views of a few aspects of NOS. The teachers focused only on the chemistry content and rarely taught or reflected NOS in their real practices. The findings indicate that the teachers did not reflect or teach NOS, which might have resulted from inadequacies in their teacher preparation courses, which did not greatly emphasize teaching NOS. The results of this research indicate that science educators and professional developers should use PCK for NOS not only as a lens to shed light on teachers' teaching of NOS but also as a framework to revisit the teaching of NOS in science teacher preparation courses.

Introduction

Understanding the nature of science [NOS] is a key element in achieving science literacy (American Association for the Advancement of Science, 1990; National Research Council, 1996). Understanding NOS requires students to engage with, participate in, and make decisions about current science-related issues. For example, students understand that science demands assessment of empirical evidence before drawing conclusions. To meet this requirement, science [chemistry] teachers should develop an informed understanding of NOS in their students and should be well-prepared to integrate NOS into their teaching (National Science Teachers Association, 2003).

Longstanding efforts have been made to develop science teachers' approach to teaching NOS (Lederman and Lederman, 2014). Understanding NOS alone is insufficient to effectively transform NOS; teachers need to be aware of the value of NOS and possess adequate understanding of NOS, NOS curricula, appropriate NOS teaching and assessment strategies, and the ability to incorporate NOS into lesson planning and teaching practices (Hanuscin et al., 2011; Vesterinen and Aksela, 2013). All of these specific requirements require the so-called pedagogical content knowledge for teaching the nature of science (PCK for NOS) approach.

PCK for NOS is a useful framework to help science teachers in successfully integrating NOS into classroom practices (Abd-El-Khalick and Lederman, 2000; Schwartz and Lederman, 2002; Hanuscin et al., 2011; Abd-El-Khalick, 2013; Bektas et al., 2013; Faikhamta, 2013; Wahbeh and Abd-El-Khalick, 2014; Aydin, 2015; Demirdöğen et al., 2015). It supports teachers to transfer NOS in a form accessible to a diverse set of students. Although there are two models of PCK (Integrative and Transformative) (Gess-Newsome, 1999), the transformative model is the more effective one. This model emphasizes transforming three types of knowledge, namely, subject matter, pedagogical, and contextual, into a unique form that impacts teaching practices (Gess-Newsome, 1999, p. 10). The literature on PCK for NOS shows that the transformative model is useful for developing teachers' PCK for NOS (Hanuscin et al., 2011; Bektas et al., 2013; Faikhamta, 2013), especially in the case of novice teachers (Kind, 2009).

This transformative model has been implemented to develop PCK for NOS in pre-service science and in-service science teachers (Hanuscin et al., 2011; Bektas et al., 2013; Faikhamta, 2013; Demirdöğen et al., 2015). For example, Hanuscin et al. (2011) conducted a secondary analysis to investigate three effective elementary teachers' teaching NOS. They reported that the teachers successfully transformed NOS into their students, but they lacked assessment knowledge. Hanuscin and colleagues pointed out that the transformative model can develop teachers' teaching NOS. Similarly, Bektas et al. (2013) investigated pre-service chemistry teachers' PCK for NOS on the topic “particle nature of matter” through a practical teaching course. The findings indicated that the teachers improved the progression of each PCK for the NOS component, with the exception of knowledge of assessment. Many science educators have developed and investigated chemistry teachers through PCK-based NOS courses. For example, Faikhamta (2013) created a PCK-based NOS course to develop chemistry teachers' orientations to teach and understand NOS. He found that the teachers who took this course developed orientations to teach and understand NOS in explicit ways. Similarly, Demirdöğen et al. (2015) investigated chemistry pre-service teachers' understanding of NOS, PCK components, and the relationship among PCK components through a PCK-based NOS course. Demirdogen and Uzuntiryaki-Kondakc (2016) put together a two-semester course based on PCK for NOS to enhance pre-service chemistry teachers' science teaching orientations. They indicated that the orientations of the teachers who took their course changed to a reformed orientation. However, they did not investigate this in an actual teaching environment. Aydin (2015) examined science lecturers' transformation of NOS in chemistry teaching by using the PCK for NOS lens and found that lecturers successfully transform NOS in graduate courses.

Newly qualified chemistry teachers are challenged to bridge the gap between theory and practice early in their career as teachers. Science educators should understand how they tie theory with real practice (Luft, 2007). However, few studies have used the transformative model to examine novice [chemistry] teachers or in-service teachers in the early years of their career. This is a significant gap in research, and there is a need to fill it by researching actual classroom practices (Lee et al., 2007; Demirdogen and Uzuntiryaki-Kondakc, 2016) of this population. Therefore, the present study employed the transformative model of PCK for NOS, which was adopted and adapted from Hanuscin et al. (2011) and Faikhamta (2013) as the lens to portray novice teachers' teaching of NOS, as well as providing in-depth information about novice chemistry teachers' transforming NOS in real-life situations. This research implements this model to further portray the effectiveness of science teacher preparation courses to science educators and curriculum developers, as well as provide a theoretical base for educating chemistry teachers. The specific research question addressed by this study is: What is novice chemistry teachers' PCK for NOS?

Literature review

Nature of science

The nature of science has been a crucial part of scientific literacy (American Association for the Advancement of Science, 1990; National Research Council, 1996). Generally, it is accepted that science education in all countries should address NOS in science teaching, for instance, Next Generation Science Standards Lead States (NGSS) (2013) provided a clear pathway for connecting NOS with each standard. Therefore, teachers should possess NOS and develop an informed understanding of it in their students. Science educators and philosophers have extensively debated the definition of NOS. McComas et al. (2000, p. 4) defined NOS as follows: “The nature of science is a fertile hybrid arena, which blends aspects of various social studies of science including the history, sociology, and philosophy of science combined with research from the cognitive sciences such as psychology into a rich description of what science is, how it works, how scientists operate as a social group, and how society itself both directs and reacts to scientific endeavors.” Another definition of NOS by (Lederman et al., 2002, p. 498) refers to it as “the epistemology combined with sociology and philosophy, science as the ways of knowing for explaining how science works, how science gains the scientific knowledge and how scientists work”.

The many aspects of NOS depend on the perspectives of science educators. AAAS (1990) divided NOS into three aspects: scientific world views, comprising scientists' beliefs and perspectives of the world and the way of learning natural phenomena; scientific inquiry, referring to the way in which scientists gain the scientific knowledge; and scientific enterprise, referring to the way in which society uses science. NGSS (2013) presented eight aspects of NOS: scientific investigations use a variety of methods; scientific knowledge is based on empirical evidence; scientific knowledge is open to revision in light of new evidence; scientific models, laws, mechanisms, and theories explain natural phenomena; science is a way of knowing; scientific knowledge assumes order and consistency in natural systems; science is human endeavor; and science addresses questions about the natural and material world. Although NOS has been added to various science curricula, there is evidence that inadequate views about many aspects of NOS continue to be held by students (Kang et al., 2005; Lederman and Lederman, 2014); pre-service science teachers (Haidar, 1999; Buaraphan, 2009); and, especially, in-service science teachers (Buaraphan, 2009; Lederman and Lederman, 2014). These views include the following: scientific laws cannot change; the scientific method is the only way to investigate scientific knowledge; the scientific method is a step-by-step process (McComas, 2000; Faikhamta, 2013); a hypothesis once proven correct becomes a theory (Dogan and Abd-El-Khalick, 2008); and science and technology are identical (McComas, 2000).

In this study, NOS was defined as a characteristic of science that reflects what science is, the nature of scientific knowledge, how to gain scientific knowledge, how science and scientists work, and the interrelationship among science, technology, and society. We relied on Lederman et al.'s (2002) NOS framework. Therefore, the following eight aspects of NOS were used as a framework: Empirical Evidence of Scientific Knowledge, Scientific Theories and Laws, Tentativeness, Myth of Scientific Methods, Observation and Inference, Subjectivity and Theory-laden, Social and Cultural Embedding, and Creativity and Imagination. We added the following three aspects of NOS: Definition of Science, Scientific Investigation, and Characteristics and Work of Scientists. We then categorized all aspects into three main aspects defined by AAAS (1990).

PCK for NOS

Pedagogical content knowledge [PCK] is an important and fundamental component of teachers' knowledge (Shulman, 1986). PCK was originally defined as a teacher's ability to blend content and pedagogical knowledge into an understandable form that is easily accessible to diverse students (Shulman, 1986). This kind of knowledge is specific to teachers and distinguishes them from content specialists. The PCK concept has been elaborated by many science educators. Grossman (1990) stated that PCK includes subject matter knowledge, pedagogical knowledge, and contextual knowledge. In another account, Magnusson et al.'s (1999) well-known model argued that PCK consists of orientations toward science, knowledge of learners, knowledge of science curriculum, knowledge of instructional strategies, and knowledge of measurement and assessment techniques. Park and Oliver (2008) extended Magnusson's framework through their Hexagonal Model, adding teacher efficacy, knowledge-in-action, and knowledge-on-action. Loughran et al. (2012) argued that PCK is more specific. They purposed two important tools to capture teachers' PCK, namely, Content Representation (CoRe) and Pedagogical and Professional-experience Repertoires (PaP-eRs).

Applying the concept of PCK to NOS, Abd-El-Khalick and Lederman (2000) argued that effective teachers should have adequate knowledge of both NOS and pedagogy. Because NOS is considered as important as other science knowledge (NRC, 1996) such as chemistry, biology, and physics, science teachers should be equipped to transfer NOS concepts to students. Among those subscribing to this view are Schwartz and Lederman (2002), Hanuscin et al. (2011), Bektas et al. (2013), Hanuscin (2013), Faikhamta (2013), Wahbeh and Abd-El-Khalick (2014), Aydin (2015), and Demirdöğen et al. (2015).

Among the various definitions of PCK for NOS, which reflect the varying perspectives of science educators, there are some similarities. For instance, Abd-El-Khalick and Lederman (2000, p. 692) characterized PCK for NOS as broad knowledge associated with activities, examples, performances, demonstrations, and history, enabling teachers to organize, represent, and present NOS in a form that is accessible to students. Teachers must therefore adapt their accounts of NOS to suit their students and to meet their goals. Schwartz and Lederman (2002) argued that PCK for NOS is a blend of NOS knowledge, subject matter knowledge, and knowledge of pedagogy, in which the overlap between these three elements is crucial. Hanuscin et al. (2011) stated that PCK for NOS is analogous to PCK models for other topics—for instance, knowledge of instructional strategies that use a particular aspect of NOS to help students understand NOS within the broader context of scientific inquiry. Bektas et al. (2013) and Faikhamta (2013) concurred with Hanuscin et al. (2011) in arguing that PCK for NOS is a knowledge base for transfer of NOS to students, which incorporates orientations toward teaching science; knowledge of science curriculum related to NOS; knowledge of learner conceptions related to NOS; knowledge of instructional strategies related to NOS; and knowledge of measurement and evaluation techniques related to NOS.

In this study, we adapted the PCK for NOS frameworks of Hanuscin et al. (2011) and Faikhamta (2013). The proposed framework comprises five components: (1) orientation to teach NOS refers to the knowledge and beliefs of the teacher on how to teach NOS with specific chemistry content; (2) knowledge of the NOS curriculum refers to knowledge of NOS related to chemistry content and knowledge of NOS instructional media for representing NOS in chemistry teaching; (3) knowledge of student's conception and learning of NOS refers to how teachers elicit prior NOS conception and their students' learning NOS styles in the context of chemistry; (4) knowledge of the NOS instructional strategy refers to how teachers integrate NOS into chemistry teaching; and (5) knowledge of NOS assessment refers to the ways in which teachers assess students' NOS conceptions in both formative and summative ways in chemistry classrooms.

Methodology

This study employed a qualitative approach based on the interpretive paradigm to investigate and describe the PCK for NOS of six novice chemistry teachers; multiple case studies were used to this end. Case studies allow researchers to explore and understand participants' real-life settings (Creswell, 2013).

Context and participants

Context is a critical factor in any such investigation and for interpreting findings (Lederman, 1999). For the present study, we selected six public schools from the Bangkok Metropolitan area. There were 45–50 students per classroom in each school. All chemistry teachers in these schools teach at the high school level, and they teach for at least 18 periods in a week. They are required to teach the core chemistry content required by scientific standards. To that end, they are allowed to choose chemistry textbooks or other teaching materials on their own.

Six novice chemistry teachers (Nana, Paul, Giftsy, Rainy, Sandy, and Arty (pseudonyms)) consented to the researchers' request for data collection. They participated voluntarily in this study. All participants were in their early years in the teaching profession, with 1–5 years of experience teaching chemistry at different high school levels (Table 1). All of them taught in different schools. Nana, Paul, and Giftsy graduated with bachelor's degrees in science education (chemistry) from a four-year teacher preparation program in the faculty of education. Rainy earned her degree in the same field but from a five-year preparation program. Sandy graduated from the faculty of science and completed a diploma in teaching. Arty held many degrees such as chemical engineering, education, and marketing.

Table 1 Teachers' demographic background
Teacher Grade level Education Chemistry teaching exp. (years) Courses taught currently Administrative duties
Nana 10th BEd (Chemistry) 5 – Fundamental Chemistry

– Chemistry II

 Lunch program/gifted student program
Paul 10th–11th BEd (Chemistry)

MA (Education Administration)

 5 – Chemistry II, IV Academic work in school
Giftsy 10th BEd (Chemistry) 5 – Fundamental Chemistry

– Chemistry II

 Academic work in school
Rainy 11th BEd (Teaching Science) 1 – Chemistry V Academic work in school/research division of school
Sandy 12th BSc (Chemistry)

Dip in Teaching

 2 – Chemistry VI Special project in school
Arty 12th BEng (Chemical Engineering)

BBA (Finance and Banking)

MBA (Marketing)

MBA (Management)

MEd (Chemistry)

 5 – Chemistry VI Registrar of school for checking teachers' absent days; checking student grade system

Data collection

“PCK is highly complex and is not easily assessed” (Baxter and Lederman, 1999, p. 158). Teachers' PCK for NOS was captured using multiple data sources (Abell, 2008) including classroom observations (Appendix I), field notes, PCK for NOS semi-structured interviews, informal interviews (Appendix II), and teacher's artifacts. The PCK for NOS interviews in this study consisted of two sections, namely, NOS and PCK for NOS.

The first section was based on the PCK for NOS frameworks of Hanuscin et al. (2011) and Faikhamta (2013), addressing the orientation to teach NOS, knowledge of the NOS curriculum, knowledge of students' conceptions and learning of NOS, knowledge of NOS teaching strategies, and knowledge of NOS assessment. In addition, the researchers adapted a few questions from CoRe (Hume and Berry, 2011). The following is an example of the line of questioning.

– If you are required to teach NOS in your lesson, how do you approach it?

○ Could you give me an example of chemistry learning activities integrated with NOS?

○ What aspects of NOS do you intend your students to know?

○ Why is it important for students to know this?

○ How can you evaluate a student's view of NOS?

○ What instructional media do you use to represent NOS?

The second section of the PCK for NOS interviews was based on Views on Nature of Science Questionnaire Form C (Lederman et al., 2002), which we modified by adding four more aspects of NOS ((1) definition of science, (2) scientific investigation, (3) relationship among science, technology, and society, and (4) characteristics and work of scientists). The questionnaire was validated by three science educators and revised based on their comments and suggestions. Before interviewing the participants, we piloted the questionnaire with five pre-service science teachers.

We started by interviewing each participant about PCK for NOS for 45 min at first meeting in the second semester of the academic year 2012. We observed four instances of chemistry teaching practice by each participant. We recorded videos of their teaching practices with their consent and, simultaneously, made field notes, conducted informal interviews with the teachers, and noted their reflections before and after each teaching period. All interviews were audio recorded. In addition, the participants were asked to supply examples of their artifacts, including lesson plans, worksheets, student tasks, and journal logs.

Data analysis

We analyzed data on PCK for NOS from various sources. We started by transcribing verbatim all raw data including video-recorded classroom observations, field notes, and PCK for NOS interviews and informal interviews with the teachers. NOS data obtained from PCK for NOS interviews were analyzed inductively and deductively by using Faikhamta's (2013) categorization of informed, partially informed, and naïve views. Informed views refer to the responses that are aligned with contemporary constructivist views, partially informed views are those characterized by partial alignment with contemporary constructivist views. Naïve views refer to the responses that are not aligned with contemporary constructivist views (see Faikhamta, 2013, p. 854). We first separated the teachers' answers in each group; subsequently, we re-categorized them according to Faikhamta's classification scheme. In each PCK for the NOS component including; Orientation to teaching NOS was classified into the nine types specified by Magnusson's Framework (1999): Process, Academic Rigor, Didactic, Conceptual Change, Activity-driven, Discovery, Project-based Science, Inquiry, and Guided Inquiry. For instance, if a teacher's responses emphasized that students studied and discovered on their own, those answers were categorized under Discovery (see Magnusson et al., 1999).

Other components of PCK for NOS (knowledge of the science curriculum related to NOS, knowledge of student conceptions and learning in NOS, knowledge of teaching strategies in NOS, and knowledge of assessment in NOS) were analyzed inductively. By using the PCK for the NOS framework, all data were coded and categorized (Table 2). Based on the emerging themes, we performed within-case and cross-case analysis to compare similarities and differences. Throughout the process, for both NOS and PCK for NOS, the first and second authors conducted independent analyses, which were then discussed. In cases of conflict, the authors reanalyzed together and agreed upon a common finding.

Table 2 Example of coding
Theme Category Coding Sample response
Knowledge of NOS instructional strategy Na59.14 implicit instruction 294 students conduct experiments and draw conclusions R: Have you ever integrated NOS in chemistry teaching?

Nana: Sure, when I let my students perform experiments

R: Could you elaborate please?

Nana: I ask them to conduct experiments in chemistry, for instance, in the chemical reaction lab, and arrive at conclusions. That is NOS.

R: You mean that whenever you let your students perform an experiment, they will learn NOS?

Nana: Yes.
Novice chemistry teachers' understanding of NOS assertion: most of them held various views of NOS based on their scientific world views, whereas they held informed views on scientific inquiry and scientific enterprise Na 58 scientific theory and law 200 alternative conceptions of scientific theory and law R: Can a theory possibly change to a law?

Rainy: Yes, if the theory can be expressed as an equation, it will be considered a scientific law

R: If someone proves that such an equation is invalid, would the law revert to being a theory?

Rainy: Yes, I believe. But theory and law represent the same level of scientific knowledge.

Findings

In addressing the research question (What is novice chemistry teachers' PCK for NOS?), a number of basic themes emerged from the multiple data sources. By using the proposed conceptual framework based on the works of Hanuscin et al. (2011) and Faikhamta's (2013), we found that the participants had limited PCK for NOS (all components). The following emerging themes were generated by coding and categorization.

Understanding of NOS—assertion: most participants held varying views of NOS based on their scientific world views, while holding informed views of scientific inquiry and scientific enterprise

Understanding of NOS was assessed by administering a PCK for NOS open-ended questionnaire and conducting interviews. As can be inferred from Table 3, the most informed views were related to scientific enterprise, scientific inquiry, and scientific world view, in that order. Interestingly, views of scientific enterprise and scientific inquiry were mostly informed, with the exceptions of the myths of the scientific method and scientific investigation.
Table 3 Teachers' views of NOS
NOS aspect Participant
Nana Paul Giftsy Rainy Sandy Arty
Note: I = informed view, P = partially informed view, N = naïve view.
Scientific world view Definition of science P I I I P P
Empirical evidence of scientific knowledge I P P I P P
Scientific theory, and laws N N P P P N
Tentativeness I I I I I I
Scientific inquiry Myth of the scientific method P P I I P P
Scientific investigation I I I I N I
Observation and inference I I I I I I
Creativity and imagination I I I I I I
Subjectivity and theory-laden P I I I I I
Scientific enterprise Social and cultural embedding I I I I I I
Relationship among science, technology, and society P P P P P P
Characteristics and work of scientists I I I I I I

Scientific world view

This comprised five sub-aspects, including the definition of science, empirical evidence, scientific theory and law, and tentativeness. For each of these, most participants held varying views of NOS. None held informed views of both scientific theory and law, and tentativeness. According to Bell (2008, p. 18), science can be defined as (1) a body of knowledge; (2) a set of methods or processes; and (3) a way of knowing. When asked the simple question what is science, participants responded that science is a body of knowledge and a set of methods. For example, one teacher (Sandy) stated that “Science is a body of knowledge about natural phenomena, accumulated through systematic human study, experimentation, and collection of accurate data in assessable form.” One of the teachers who held informed views stated that science is not only a body of knowledge or a method by which knowledge is constructed. Some teachers defined science according to its disciplines—mentioning, for example, “Science is knowledge in various disciplines with different origins, such as chemistry and astronomy. Scientists use various methods, such as observation, experiment, and so on, to come up with scientific knowledge, but whether their knowledge is accepted or not depends on their evidence …but their knowledge is not durable, it can be changed through the development of instruments” (Rainy).

In relation to empirical evidence, four of the participants (Paul, Giftsy, Sandy, and Arty) held partially informed views. They believed that science differs from other disciplines in terms of how it investigates the world—for instance: “an experiment or method of investigation makes science different to other disciplines.” Only two teachers mentioned that science requires empirical evidence and that this distinguishes it from other subjects.

It was surprising to find that no one held informed views in relation to scientific theory and law. Teachers with partially informed views believed that both scientific theory and law constituted the body of knowledge and could explain natural phenomena. However, they failed to define exactly the meanings of “law” and “theory,” as, for instance, in the following: “Law is the short account and is always written as an equation, while theory is the explanation” (Nana, Rainy). Arty held the naïve view that while the scientific law is the rule of nature as accepted and repeated by scientists, theory is an accepted principle.

With regard to tentativeness, all participants held partially informed views. When asked about the durable or changeable nature of scientific knowledge, all participants responded that scientific knowledge could be modified or changed by further evidence. However, three participants (Nana, Rainy, and Sandy) believed that a law could not be changed, whereas a theory could be. Another participant (Arty) strongly believed that neither type of knowledge could change.

Scientific inquiry

This comprised five sub-aspects, including the myth of the scientific method, scientific investigation, observation and inference, creativity and imagination, and subjectivity and theory-laden. As summarized in Table 3, most participants held informed views of each of these, with the exception of the myth of the scientific method, scientific investigation, and subjectivity. The myth of the scientific method encompasses the meaning of the scientific method and the steps in the said method. Two teachers who held informed views on this issue believed that the scientific method is hypothesis testing or a way of asking questions, in which the steps or process are not always fixed (Giftsy, Rainy). Two others understood the meaning of a scientific experiment, but strongly believed that it was a fixed-step process. In their view, if a scientist does not follow the steps, s/he will obtain faulty or inaccurate results.

In respect of scientific investigation, only Sandy strongly believed that the scientific experimentation is the main method for the development of scientific knowledge. She relied on scientific experiments and stated that most scientific knowledge resulted from scientific experiments. By contrast, other teachers believed that there are various ways of advancing scientific knowledge.

All participants held informed views in relation to observation and inference, and creativity and imagination. They noted that scientists use collections of observed data and inferences to construct scientific knowledge. They also realized that scientists need creativity and imagination when conducting an investigation. Nana stated that scientists generally use every step of the scientific method—proposing hypotheses, designing experiments, designing tables of results, and so on.

In relation to subjectivity and theory-laden, Nana did not mention the source of scientists' subjectivity, but she believed that it depends on the data collected and that there could be more than two theories if results differed. Most participants understood that the background, experiences, and prior knowledge of scientists influence their ways of interpreting data, which implies that they might see things differently (Paul, Giftsy, Rainy, Sandy, and Arty).

Scientific enterprise

This encompasses socially and culturally embedded factors; the relationship among science, technology, and society; and characteristics of scientists. Interestingly, all participants held almost all informed views under each of these headings. In terms of socially and culturally embedded factors, they stated that human society and culture directly influence science, offering examples such as cloning in the Thai context. In their view, such advances in scientific knowledge will be resisted in our society because of traditional beliefs. They also argued that human cloning should not receive any government support.

Interestingly, all participants understood the relationship among science, technology, and society. They realized the differences between science and technology. All teachers also noted that science, technology, and society interact, and that advancement of science and technology benefits society. Most of them, however, mentioned that technology requires scientific knowledge to meet human demands. These responses sounded like informed views, but not all technologies require scientific knowledge. A lot of technological procedures were developed before the underlying scientific knowledge was discovered. Therefore, all teachers were categorized as having partially informed views in this respect.

In relation to the characteristics and work of scientists, all participants first mentioned Albert Einstein when asked about the image of scientists. Most participants opined that scientists should have positive habits such as curiosity, diligence, opened-mindedness, and reasonableness. In investigating natural phenomena, it was considered that scientists could work alone or collaboratively with peers.

Defining NOS

In addition to understanding NOS, the teachers were asked to define the term by answering the simple question Have you ever heard the phrase NOS, and what in your opinion is the meaning of NOS? They viewed the meaning of NOS in two dimensions: using scientific processes to acquire scientific knowledge and the general characteristics of science. The first dimension emphasized the use of science processes by scientists as tools in the pursuit of knowledge. For example, according to Nana, “[the nature of science is] using science process skills to search for knowledge and to construct knowledge—for example, in the case of atomic theory, scientists used experimental data to support their claims.”

Paul: “[the nature of science is] I think, about pure science that advances by means of scientific experimentation. It needs no additional ingredient other than reasoning.”

However, in relation to the second dimension, Giftsy, Rainy, and Sandy understood the meaning of NOS in terms of the characteristics that make science unique, as below.

Giftsy: “I think it is characteristic of science to demand evidence, as scientific knowledge must be validated by the scientific community.”

Rainy: “The nature of science is reflected in the image of science—for instance, if someone was asked what science is, they would view NOS as the characteristic of science that relates to scientific experimentation.”

Sandy: “I think about the meaning of science as scientific inquiry that leads us to scientific knowledge, and in terms of the differences between science and other disciplines.”

Arty, who came from an engineering background, did not know that NOS was addressed in science curriculum standards: “Actually, I had never heard this phrase before, but I tried to find about it in a textbook. It is about using the process and method of science in teaching through inquiry.”

Orientation to teaching NOS—assertion: even among those with varying orientations to teaching NOS, teaching practices did not align well with orientations. Analysis of the data from the PCK for NOS questionnaires and interviews indicated that all participants had varying orientations to teaching NOS. The question used to elicit this information was if you wished to integrate NOS into your chemistry teaching, how would you teach it? Teachers' orientations were found to include guided inquiry, inquiry, project-based science, and process- and activity-driven orientations (Table 4). Those using guided inquiry (Rainy, Sandy, and Arty) believed that students could work collaboratively to answer teachers' questions. They also believed that students could investigate using various tools prepared by the teacher. Nana's orientation was activity-driven. She stated that students could conceptualize scientific models by making real models to observe a natural phenomenon and gain deeper understanding of the model in the process. By using a project-based approach, Giftsy believed that students could learn NOS by conducting science projects autonomously and in collaboration with their peers. Paul stated that his students learn NOS by engaging in real-world situations. Nana preferred using multiple activities to encourage her students.
Table 4 Teacher's orientation to teaching NOS
Orientation Teacher Example of responses
Guided inquiry Rainy In this titration task, I give students the question and let them work collaboratively to facilitate discussion. Then, they need to bring the scientific equipment that I provide to the front of the class. Then, they are to use their science process skills and debate within their group.
Sandy I let students solve problems devised by me and let them design their scientific investigation—for instance, to answer a problem, the students prepared model comprising balls to explain isomerism.
Arty I use a jigsaw game to let students find the answers which given by me. Students use their skills of observation and science process, and finally, they evaluate their findings. The teacher assigns standard scores to student assignments and compares the findings of each group, thus allowing students to discuss their findings.
Activity-driven Nana I ask students to make an atomic model or the shape of a covalent molecule. That will help them see the real picture, enhance their understanding to an extent greater than that achieved by seeing a picture in the text book.
Project-based science Giftsy I let them do science projects. Students can learn NOS by working collaboratively in groups, conducting scientific investigation, designing experiments, and collecting data.
Inquiry Paul The teacher should let the student observe the real situation—for instance, in the case of polymers, let them build on a question about polymers; send them to a village to observe polymer waste, or bring them to the factory to see how polymers are managed.

We adapted Faikhamta's (2013) approach to distinguish between explicit and implicit instruction. It is no surprise that all participants' responses were categorized as implicit instruction because all of them believed that students learn autonomously about NOS through activity and without explicit debriefing. Despite the views they expressed through questionnaires and interviews, most of the participants' teaching practices did not align well with their orientations. For instance, Paul (whose orientation to teaching NOS was inquiry-based) was categorized as didactic and emphasizing academic rigor in his teaching, with no NOS element. In teaching four chemistry concepts (calculation of pH and pOH, covalent bonding energy, hydrolysis of salt, and half life of radioactive substances), he always started by revising and eliciting responses to students' prior knowledge. He then corrected students' alternative conceptions via explanation on the blackboard. He used many exercises from student workbooks and national tests before explaining. Similar to most of the other teachers (Nana, Giftsy, Sandy, and especially Arty), he taught carbohydrates, protein structure, and protein testing by first questioning and explaining the concepts, and using questioning techniques and essay worksheets. He randomly asked students to answer exercises in the worksheet and awarded extra points to students who answered correctly. He always added additional detail to the concept and asked students to note said details in their worksheets.

Only Rainy (who favored guided inquiry to teach NOS) employed multiple teaching strategies. She used guided inquiry activity in teaching metal coating, allowing her students to find what would happen and to generate their own explanations of the underlying phenomena. She started by revising her students' prior knowledge about galvanic cells, cathodes, and anodes before moving to electrolytic cells and asking students to note the differences between the two types of cells. She then asked students to get the required equipment and briefed them about experimental procedures. Finally, she asked students from each group to share and discuss their results and draw conclusions. In the remainder of the lesson on electrolytic cells, she sought to elicit and review students' prior knowledge about metal coating. She then used PowerPoint to explain and brief them about the previous activity. She started by explaining the concept of electrolytic cells, as used under melting and aqueous conditions. With regard to the elements and compounds in the industry process lesson, she encouraged her students to acquire knowledge from multiple sources. Students were required to present experimental results to their peers.

Knowledge of the NOS curriculum—assertion: although most teachers realized that NOS was addressed in the national standards, no one explicitly portrayed NOS as a key learning objective in lesson planning or teaching practice. With the exception of Arty, the teachers (Nana, Paul, Giftsy, Rainy, and Sandy) knew that NOS was addressed in the national standards (Thai science curriculum standards). They realized that they should integrate NOS whenever they taught chemistry concepts, but only a few of them included NOS as a learning objective when planning chemistry lessons. Instead, they focused exclusively on chemistry concepts. In the case of an atomic structure, the following are examples of learning objectives planned by Nana:

(1) Explaining the origin and formation of petroleum

(2) Explaining the principle of fractional distillation

(3) Explaining the products of fractional distillation

(4) Working collaboratively with peers

(Nana's lesson plan)

Nana based these learning objectives on the science textbook, and she already knew the scope of this content. Her learning objectives focused mainly on the chemistry content. As in other lessons (e.g., solutions, polymers, and preparation of solutions), her learning objectives followed the same pattern. After each teaching period, the researcher asked her about these objectives again. Nana responded by stating that her task was accomplished by each goal that she had set. Nana, however, mentioned about NOS in the curriculum. She stated: “…Today, I met the requirements I had set; they need to understand how petroleum is the product of fractional distillation of crude oil. I set these objectives from the curriculum and textbooks…”

The same was true of the other teachers. For instance, in teaching the shape of covalent molecules, Giftsy wanted her students to understand how each molecule's shape was formed and to be able to explain the arrangement of balloons in those shapes. Her objectives were as follows:

(1) Explain the meaning of covalent molecules' shape

(2) Explain the factors affecting the shape of covalent molecules

(3) Predict the shape of covalent molecules

(4) Explain how to use the valence shell electron pair repulsion (VSEPR) theory

(5) Conduct activities on the arrangement of balloons in the shape of molecules rather than atomic arrangements

(Giftsy's lesson plan)

She mentioned that she set her objectives by considering that students should understand the big picture. As she said, “all learning objectives that I write should be related to the national standards.” However, in meeting the requirements of said standards, none of the participants' objectives acknowledged that NOS is as important as chemistry content, and it was unsurprising that most participants' lesson plans and teaching practices did not include NOS in the learning objectives.

Interestingly, most teachers mentioned that in the curriculum, NOS was similar to scientific process skill, which scientists use to discover explanations for natural phenomena. They believed that they were teaching NOS by allowing their students to conduct experiments. The following is an example of this perception.

R: Did you integrate NOS in your teaching today?

Sandy: I could not integrate it completely, but at least I allowed them to work in groups to investigate through their textbooks or the Internet. Students need to use this data for mind mapping, and they can learn NOS through this activity.

It is obvious that most teachers had inadequate knowledge of this component, given how all of them relied on the chemistry textbook. While they realized that NOS is part of the science curriculum, their lesson plans and teaching practices did not reflect this.

Knowledge of students' conceptions and learning of NOS—assertion: all teachers emphasized only learner difficulties in chemistry concepts, but NOS was still missing. All teachers emphasized learner difficulties and prior conceptions of chemistry concepts every time they taught. They planned many strategies to deal with difficulties that they may encounter at any time in real situations, as in the following conversation between Rainy and a student when she taught metal coating for the first time.

Rainy: Do you remember the electrode charges and which is positive or negative?

S: Yes, I do.

Rainy: And what about E0 cell? Which cell has negative E0?

S: Electrolytic cells—galvanic cells are the opposite.

Rainy: You should know the basic principles of the two cells first.

After teaching, she expressed her concerns about prerequisite student understandings before they learned about electrolytic cells: “In this lesson, if I did not revise the previous lesson about galvanic cells, my students would be confused about electrode polarity. Hence, I need to clarify the distinction between galvanic and electrolytic cells, and then move to metal coating.” This statement confirms her concerns about students' difficulties and prior knowledge.

Similarly, before her third time of teaching (about alcohol and ether), Sandy stated that “They should understand about the poles in molecules, positive and negative, and I'm really concerned that the topic for today—the reaction of alcohol and ether—is a difficult one that may confuse them.” Drawing on her experience of teaching this topic last year, she tried to explain after asking her students to make a presentation. Sandy explained that “the alcohol group based on alkane was added to the OH group. The formula is R–OH, where R refers to an alkyl, in which alkane is substituted by the hydroxyl group in the H atom.”

Arty, who was quite aware of learner difficulties, relied on his worksheet to summarize and rearrange the sequence of chemistry content from many textbooks because he believed that one textbook would be inadequate for his students. As he described it, “I try to rearrange the sequence of the content by following the textbook, but I simplify and adapt it in my own words to make it easy for diverse learners to understand.”

In conclusion, although all the teachers emphasized learner difficulties and prior knowledge of chemistry concepts whenever they taught, they never asked or probed students about NOS. In failing to recognize that NOS is as important as chemistry content, it could be said that all teachers had limited understanding of students' difficulties and conceptions of NOS.

Knowledge of the NOS instructional strategy—assertion: most participants used lecture-based instructions to teach chemistry. Based on classroom observations and interviews, most teachers were found to rely on teacher-centered teaching over the entire semester. While these teachers (Nana, Paul, Giftsy, Sandy, and Arty) depended on lecture-based teaching as their main strategy, Rainy tried to use various strategies, including structured inquiry and lectures, to teach chemistry. All teachers' patterns commenced with a short question-and-answer session, followed by a lecture and practice in the student workbook. The following is an example of Paul teaching pH and pOH calculation.

Paul: As you know, the formula is pH + pOH = 14. I will give you a new formula for calculation… (Paul shows how to derive the new formula) and look in your worksheet.

SS: [jot down in their worksheets]

Paul: You can do it by yourself—it is quite easy, right?

SS: Yes.

Paul: Move to the next example; now it's your turn. I'll give you three minutes to complete this.

Paul's teaching pattern remained the same throughout the rest of his teaching. According to Paul, he did not rely on strategies other than lectured-based teaching because he strongly believed that lectured-based teaching was more effective in this context than other teaching approaches: “In my experience, I think lecture-based teaching is quite effective because when I studied chemistry at university, our teachers always used this strategy, and I understood well.” In another example, he again relied on lecture-based activity. He started by revisiting concepts from the previous period and explaining them to students. He then completed the lesson by asking students to solve the problems in the test.

Arty used a didactic approach, relying on questioning techniques and students' worksheets. Students were randomly selected by number to answer each question, with extra points awarded to those who gave the correct answer. Similarly, Nana, who taught four topics (petroleum, solutions, polymers, and preparation of solutions) always started the observed sessions by eliciting her students' prior knowledge and lecturing on content, using the blackboard. Nana often allowed her students to sit in groups to jot in their notebooks. As a way of checking her students' conceptions, she always used questioning techniques. She always gave them many everyday examples and simplified difficult concepts by using language that was understandable to students. In assignments, she often allowed students to help each other.

Interestingly, in the three topics that Giftsy taught (the shape of covalent molecules, preparation of solutions, and solution units), she ran guided inquiry activity only for the first topic. After revising students' conceptions of covalent molecules and conducting a pre-test, she described the VSEPR theory and the method for identifying the shape of a covalent molecule. To see the shape, she initiated a balloon activity, asking students to discover the shape of covalent molecules and explain the results of shaping. For the remainder of the lesson (solution preparation and solution units), she used a lecture-based approach to explain the meanings of solution and units. Having taught a calculation technique to solve the test problems, she continued to rely on lecturing over the rest of the lesson. Similarly to Sandy, she encouraged her students to create mind mappings from their textbooks about ether and alcohol during two classes. In the other classes, she relied on teacher-centered teaching to explain alkanes, alkenes, and alkynes.

Only Rainy, who held well-informed NOS views, employed multiple strategies to teach chemistry. In her metal coating class, she began by revising students' understanding of the electrolytic cell and the advantages of this cell. She then divided her students into two groups to try to coat a nail with copper. Students were required to connect the positive and negative electrodes to the nail. She asked the students to investigate what would happen if they connected the electrodes in the reverse fashion. At the end, the students were required to communicate their results to their peers. She briefed the reactions again and summarized the experiments.

It is not surprising, then, that no one explicitly taught or reflected NOS in their teaching practices compared to their lesson plans. However, Giftsy unconsciously reflected NOS in describing the work and characteristics of scientists to her students. In her lesson on preparation of solutions, she began by explaining both the formula for solution preparation (N1V1 = N2V2 and mol = NV/1000) and the associated calculation steps. While describing the scientific apparatus used for solution preparation on the blackboard, she mentioned NOS: “…preparation of solution is the one of many duties of chemists. They use such tools to prepare the solution as we learned today, doing as scientists do in the laboratory. They need to be careful when preparing—it's not as simple as the small scale we attempted…”

Knowledge of NOS assessment—assertion: teachers did not assess students' NOS in lesson planning or teaching practices. Although in the questionnaires and interviews all teachers mentioned using both formative and summative assessment to assess students' understanding of NOS, they did not include these strategies to assess NOS in either their lesson plans or teaching practices. For instance, Rainy (who was categorized as having more informed views of NOS) did not consider NOS as a learning outcome that she needed to assess, nor did she know when she should assess it or where she should place it in the lesson plan. When asked why she did not assess NOS, Rainy said “I think my students could learn NOS simultaneously; through my activity, I can see their development. Actually, I do not know where should I add NOS assessment in my lesson plan because my school has a fixed lesson plan form, and I need to follow the form” (Rainy—first post-teaching interview).

All teachers always used informal assessments such as questioning, quizzes, and students' worksheets to assess chemistry concepts, as well as questioning techniques. For instance, Arty (who always relied on questioning techniques) used questioning and scoring techniques whenever he taught. He claimed that he tried to encourage active learning by selecting students randomly by number: “I use questioning to engage my students in learning activities. In some questions, students are required to explain a concept in detail, and I can check their understanding immediately. It is quite useful in some periods, but I often find that the same students answer my questions.” The following is an example of his questioning technique.

Arty: Go to number two, how can we test proteins?

S1: Use the biuret solution.

Arty: What is the biuret test?

S1: We can test protein substances by using the biuret reagent.

Arty: Yes, how can we prepare the biuret solution?

S1: By adding CuSO4 to nitrate.

Arty: No, to NaOH; ok next…

In addition, teachers always used formal assessment (i.e., summative assessment) to evaluate their students' understanding, including tests, quizzes, homework, tasks, worksheets, and journal logs. For instance, Nana always asked her students to work in their groups to accomplish tasks that she set. In her polymer unit, students were asked to work in groups to elicit crucial content from a textbook before presenting it to other students. Each group was also required to ask and answer peer questions: “I often asked my students to complete tasks in groups in class. I need to evaluate their understanding; I know they do not want to do paper-pencil tests, but sometimes, it is useful to assess what they have understood.” Sandy did the same and added further student tasks, including mind mapping and content summary. She also observed students’ presentations and corrected their work. Sandy assessed and evaluated students' performance on the basis of their work.

Rainy used both formative and summative assessments in her class. She began with questioning and then invited other students to answer. Experiment reports were used as for summative assessment, and each group was required to submit one. For instance, in her metal coating class, she allowed her students to design experiments in their own way, write the procedure, and explain why they designed it in that way. Finally, she asked her students to write a journal log once a week and used this as another means of assessing their understanding and reflecting her teaching. She said “I love giving multiple tasks to my students, and I always urge them to explain what they understood. Questioning is the most important technique for checking students' progression. Whenever I ask my students to perform an experiment, they are required to send a report to me. And each week, they are required to send their journal logs to me.”

To conclude this component, teachers used formative and summative assessments, including questioning, tests, quizzes, journal logs, worksheets, and presentations, to assess their students' understanding. However, none of them assessed NOS either formatively or summatively in their lesson plans or teaching practices, emphasizing only the chemistry content.

Conclusions, discussion, and implications

This study attempted to picture novice chemistry teachers' transforming NOS in real practice in school through the lens of PCK for NOS. The findings show that all participating teachers had limited PCK for NOS in each component, despite having mostly informed views of each aspect of NOS. Although the interview data suggested that they understood PCK for NOS and held adequate views of each NOS component, their practices did not align well with those data because they integrated few, if any, NOS components in their lesson plans and teaching practices, and they did not explicitly demonstrate that they understood PCK for NOS or NOS aspects. Almost all of the participating teachers embraced a teacher-centered pedagogy, focusing on rote memorization and relying on chemistry textbooks. They concentrated on the chemistry content and used lecture-based learning almost exclusively. This is consistent with the findings of Al-Amoush et al. (2012) and Al-Amoush et al. (2011) that chemistry teachers typically adopt a teacher-centered style. However, one participant (Rainy) tried to use various learning activities that suited both the chemistry content and her students, such as experiments, lecture-based teaching, and hands-on activity. In general, however, it could be said that these teachers exhibited only a superficial understanding of PCK for teaching science/chemistry or PCK for NOS at the subject-specific level, and they could not advance to the topic-specific level. One factor that might account for this deficiency is the failure of teacher preparation programs. Science (chemistry) teacher preparation programs might be the central causes of teachers' limited of PCK for NOS. Although the courses in these programs have addressed NOS (its definition, importance, teaching strategies, and activities), these courses do not focus enough on how to explicitly adapt NOS specifically to chemistry. Therefore, the result of the present study show that teacher preparation institutions succeed somewhat in promoting teachers' understanding of NOS and importance of the role of NOS, but they fail explicitly in helping teachers represent or transform NOS in chemistry classes. As we saw in the findings through the lens of PCK for NOS, most teachers hardly explicitly integrate or reflect NOS in their practices and lesson plans. In addition, some of them believe that NOS could be learned implicitly through teaching activity, without explicitly emphasizing it.

Although all of these teachers held adequate views of NOS or had strong backgrounds in chemistry, they could not necessarily transform those advantages into lesson plans and practices. Despite claiming to understand NOS, most failed to explicitly demonstrate concrete knowledge or ability in their teaching practices, interviews, and lesson plans. This is consistent with the findings of Abd-El-Khalick et al. (1998), Shah (2009), Dogan et al. (2013), Sarieddine and BouJaoude (2014), and Deniz and Adibelli (2015) that even teachers with adequate understanding of NOS did not always transform this in the classroom, possibly because most of them had no experience of NOS professional development programs, which is consistent with other findings that the lack of NOS experience, NOS resources, and models of how to transform and integrate NOS in action or in chemistry textbooks without explicitly emphasizing NOS may critically impede NOS teaching (Schwartz and Lederman, 2002; Abd-El-Khalick et al., 2008; Hanuscin et al., 2011; Niaz and Maza, 2011; Bektas et al., 2013; Dogan et al., 2013; Demirdöğen et al., 2015). Interestingly, although these teachers were aware of the vital role of NOS, they did not teach or add any aspect explicitly, perhaps because they understood NOS as referring to the body of knowledge acquired through the scientific method. Most of their teaching was lecture-based, and therefore, it was difficult for them to integrate NOS. Aydin (2015) argued that having rich and deep knowledge of chemistry enabled teachers to design NOS content-embedded activities, but our findings suggest otherwise. The findings of the present study also indicate that robust chemistry content, adequate NOS understanding, or pedagogical knowledge alone is not sufficient to transform NOS in practice. The study participants neither designed nor taught chemistry content at both subject-specific and topic-specific levels. All participants, from both science and engineering backgrounds, had robust experience in chemistry, scientific work, and chemistry content. Yet, compared to teachers from the faculty of education, they could not use NOS content-embedded activities or examples of NOS in chemistry, despite having at least one or two years of experience in education. However, it is not clear whether teachers who graduated from the faculty of education could reflect NOS in chemistry teaching. Some (Giftsy and Rainy) continued to rely on implicit NOS activity; while Rainy, for instance, believed that her students could learn NOS through activities in class or she believed that she taught NOS, but did not do so explicitly. By contrast, Nana and Paul did not integrate NOS in their practices, perhaps because their teacher preparation programs did not place sufficient emphasis on NOS and explicit-reflective NOS (Bektas et al., 2013; Dogan et al., 2013; Sarieddine and BouJaoude, 2014), or mentioned NOS only superficially. Examples of NOS alone may not be enough to help chemistry teachers to foster their PCK for NOS; as Bektas et al. (2013) and Wahbeh and Abd-El-Khalick (2014) suggested, any such course or professional development program should not include only explicit reflective NOS but should also focus on embedding NOS content in specific chemistry topics. In addition, courses should not overlook adding the definition of NOS, because our findings indicated that a few teachers never knew of NOS before and had hardly paid attention to it, despite the mention of the topic in the national standards. One possible cause might be the nature of school teachers' context. First, they lack classroom experience related to NOS. Second, based on these participants' duties in school, all were required to teach at least 18 periods per hour in addition to performing other duties in the school. Third is the class size handled by the teachers—there were at least 45–50 students in each class. Fourth, administrators' policies focus only on students' achievements and success in terms of examination scores at the university level. Teachers might face some struggle and have limited time to deal with and prepare their lessons.

In collecting and analyzing data, a few questions emerged. Are the existing models of PCK for NOS sufficient to explain teachers' PCK for NOS? Do we need to modify or revise the existing models? Are there any interplays or relationships between PCK for teaching science/chemistry and PCK for NOS? If yes, what are they? Are there relationships among subject matter knowledge, NOS knowledge, and PCK for teaching science/chemistry? If yes, what are they? Does PCK for teaching science/chemistry influence PCK for NOS, or does PCK for NOS influence PCK for teaching science/chemistry? If yes, how? In the present study, none of the participants had ever enrolled in an NOS professional development program since they started teaching chemistry. Because we could not directly use the PCK for NOS lens to capture the teachers' understanding from the outset, we looked through the lens of PCK for teaching science/chemistry to explain the teachers' PCK for NOS.

One implication of this study is the need for science teacher educators, lecturers, professional developers, curriculum developers, and other researchers to rethink how science teacher preparation programs address NOS to meet the required standards. The measures of introducing NOS knowledge and NOS teaching strategies have proved to be inadequate thus far. How can we prepare pre-service chemistry teachers and help novice teachers to transform NOS in the chemistry classroom? To this end, the literature suggests the use of PCK for NOS as a conceptual framework to design NOS experiences for both pre-service and in-service chemistry teachers (Dogan and Abd-El-Khalick, 2008; Faikhamta, 2013; Vesterinen and Aksela, 2013; Demirdöğen et al., 2015). This would be of value not only for understanding and teaching NOS but also for integrating NOS at the topic-specific level. Moreover, the intersection of NOS content, chemistry content, and pedagogical knowledge in the chemistry classroom is required. This study also supports the PCK for NOS models described by Schwartz and Lederman (2002), Abd-El-Khalick (2013), and Wahbeh and Abd-El-Khalick (2014), according to which teachers' PCK for NOS should cover three dimensions to teach NOS successfully. Teachers should incorporate all the three dimensions. As Hanuscin (2013) pointed out, beyond teaching NOS alone, we should place greater emphasis on other PCK for NOS components such as assessing NOS at both subject-specific and topic-specific levels. In addition, courses such as science methods in teacher preparation programs should afford students the opportunity to put theory into practice by writing lesson plans and teaching in real classrooms. There should be a program to offer ongoing support to practicing teachers. While we did not provide any such experience to the teachers, there is possibly a relationship between PCK for teaching science/chemistry and PCK for NOS. Future studies should investigate the effectiveness of teacher preparation programs in terms of their emphasis (or the lack of it) on PCK for NOS.

Limitations

First, this study was limited to only six novice chemistry teachers from Thailand, who had no more than five years of experience teaching chemistry. Our findings may not be generalizable to other novice teachers, but our multiple case studies do provide in-depth knowledge of teachers' understanding and practices in the early years of their teaching career. Second, we used an adapted PCK for the NOS model (Hanuscin et al., 2011; Faikhamta, 2013) to portray teachers’ transforming NOS in actual chemistry class. In future CoRe could be used as another tool to help science educators capture teachers' PCK for NOS or to investigate the factors that impede or support novice teachers’ transforming NOS at the high school level.

Appendix I: guiding for classroom observation

PCK for NOS components Observation
Orientation to teach NOS – Analyze and clarify how teachers teach NOS when teaching chemistry, aims of science teaching
Knowledge of the NOS curriculum – Analyze and identify teachers' objectives in teaching practices and lesson plans
– Analyze and identify instructional media used by teachers' in their classes
Knowledge of students’ learning and conception – Analyze and identify teachers' probing of NOS in students
– Analyze and identify teachers' understanding of student's difficulties with regard to NOS
Knowledge of the NOS teaching strategy – Analyze and seek teachers' strategies of representing NOS in chemistry teaching
Knowledge of NOS assessment – Analyze and identify teachers' use of assessment tools and methods to evaluate students’ conceptions of NOS
(Adapted from Buaraphan, 2006).

Appendix II: example of an interview protocol

Pre-teaching

(1) What are your objectives in terms of students' learning?

(2) How will you teach your students to meet said objectives? What approach you intend to use and why did you choose it?

(3) Do you integrate NOS with your chemistry teaching? If yes, please explain how you do that. If not, why?

(4) Do you think your objective of NOS integration is suitable for the chemistry concepts you taught? Please explain how.

Post-teaching

(1) How was your teaching?

(2) Did you think your students have reached your objectives as you intended? If so, how did they get there?

(3) Did you integrate NOS with your objectives? If yes, which aspect of it did you integrate and why?

(4) Did you think your teaching reflected NOS? If yes, explain how and why.

(5) Could you capture your students’ alternative conceptions of NOS? If yes, what are those and how did you detect them?

(6) Have you assessed students’ conceptions of NOS? If yes, how?

(7) What problems did you face during teaching?

Acknowledgements

The research was supported in part by the Graduate Program Scholarship from the Graduate School, Kasetsart University. The authors sincerely thank Associate Professor Dr Kim Chwee Daniel Tan, Dr Wendy Nielsen, and Associate Professor Sunan Sangong for reviewing and improving the first draft of this paper. The authors would also like to thank Assistant Professor Bussba Thontong and Mrs Pabi Maya Das for their help in revising the writing style.

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