Elements constituting and influencing in-service secondary chemistry teachers’ pedagogical scientific language knowledge

Abstract

Chemish – the scientific language of chemistry – is crucial for learning chemistry. To help students acquire the competencies to understand and use Chemish, chemistry teachers need to have a sound knowledge of teaching and learning Chemish: Pedagogical Scientific Language Knowledge (PSLK). But still, despite the importance of this knowledge, the question remains what exactly it is. Based on a model for science teachers’ PSLK developed through a systematic review, this study seeks to validate the developed model by interviewing experienced chemistry teachers, filling the model with more detail, and examining further and systematising chemistry teachers’ PSLK. Therefore, semi-structured interviews with 19 German secondary chemistry teachers are conducted. The interviews are analyzed both deductively using the results of the systematic review and inductively following the approach of Grounded Theory. Finally, the elements of PSLK resulting from the systematic review, as they are knowledge of (i) scientific language role models, (ii) the development of the concept before the development of the scientific language, (iii) making scientific terms and language explicit, (iv) providing a discursive classroom, (v) providing multiple resources and representations, (vi) providing scaffolds for scientific language development, (vii) communicating expectations clearly, and (viii) specific methods and tools for teaching and learning the scientific language, could be validated and described in more detail, and even new elements, as they are the knowledge of (ix) the motivation when learning scientific language as well as (x) the knowledge of lesson preparation and follow-up, could be identified and described through the interviews. Furthermore, elements influencing the development of and PSLK itself are characterized. Implications to foster Pedagogical Scientific Language Knowledge during teacher preparation will be given.

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Introduction

Chemish (Markic and Childs, 2016), the scientific language of chemistry, plays a crucial role in chemistry class's teaching and learning process. Chemistry content cannot be learned without Chemish, as every activity in the classroom is bound to at least one dimension of language (Childs et al., 2015). In the sense of Halliday (1993), learning chemistry involves learning through, learning of, and learning about Chemish. The reasons that Chemish is so complex lie, e.g., in the use of technical and non-technical terms, the special syntax, mathematical elements, symbolic language, and different meanings of terms in the context of chemistry and everyday life (Lemke, 1998; Childs et al., 2015; Liu and Taber, 2016; Markic and Childs, 2016; Liu, 2018). And thus, Chemish is rather a hybrid composite than a ‘language’ including multiple modes of meaning making. but as such used as a system for meaning-making. However, the term ‘language’ is thus used for convenience. Additionally, Chemish includes three different representational levels: macroscopic, sub-microscopic, and representational (Johnstone, 1993) which are differentiated by the use of language. In contrast to learning an additional language where the native language can serve as a frame of reference or mediator, Chemish has to be learned simultaneously with its frame of reference, i.e., the chemical concept (Vygotskiĭ, 1986). Thus, Chemish can be an obstacle for students when learning chemistry (e.g., Wellington and Osborne, 2001). Being aware of this as a chemistry teacher and counteracting students’ difficulties with Chemish is especially important given the fact that students’ comprehension ability correlates with their performance in chemistry (Pyburn et al., 2013). In consequence, to foster students’ understanding in and of chemistry, chemistry teachers must act as linguistic guides (Laszlo, 2013) and thus help students master scientific language (Brown and Ryoo, 2008). Therefore, chemistry teachers need a special kind of teacher knowledge: Pedagogical Scientific Language Knowledge (PSLK).

Current research, on the one hand, identifies that (pre-service) teachers lack (i) knowledge of the scientific language (e.g., Gyllenpalm and Wickman, 2011; Carrier, 2013; Mayaba et al., 2013; Seah, 2016; Vladušić et al., 2016; Salloum and BouJaoude, 2020; Buxton and Caswell, 2020; Meier et al., 2020; Mönch and Markic, 2022a) and (ii) awareness of scientific language or their task to teach scientific language (Moore, 2007; Markic, 2015; Seah and Silver, 2022). On the other hand, less is known of science teachers’ actual teaching practice in terms of teaching scientific language (Yore and Treagust, 2006; Kelly, 2014; Childs et al., 2015) and what their knowledge is comprised of.

The present article is part of a PhD research project on Pedagogical Scientific Language Knowledge. This article is preceded by two other studies: in the first study, pre-service chemistry teachers’ PSLK is explored (Mönch and Markic, 2022a) and found to be rather scant. Thus, a need to know more about what Pedagogical Scientific Language Knowledge consists of emerged. In the second study, therefore, a systematic review was conducted to systematise science teachers’ PSLK (Mönch and Markic, 2022b). However, the model of PSLK needs further elaboration as research on teachers’ knowledge and their teaching practices of scientific language remains sparse, is mostly related to science in general but not Chemish in particular, and mainly relies on case studies. Thus, the present study aims to validate the developed model of PSLK focusing on the scientific language of chemistry and to further investigate and systematize German chemistry teachers’ PSLK and elements constituting and influencing it in more detail. This aims to use the final version of systematized PSLK during teacher preparation since “it is important to conceptually map out the types of knowledge to move towards adopting measures to facilitate their development in teachers” (Morton, 2018, 278).

Theoretical framework

Teacher knowledge

Shulman (1987) first proposed seven strands of teacher knowledge, Pedagogical Content Knowledge (PCK) being one of them. PCK is the “special amalgam of content and pedagogy that is uniquely the province of teachers, their own special form of professional understanding“ (Shulman, 1987, 8). These days, the construct of teacher knowledge has often been referred to and further developed, especially concerning PCK (an overview can be found in de Sá Ibraim and Justi, 2021). Carlson and Daehler (2019) lately presented the Refined Consensus Model (RCM) of Pedagogical Content Knowledge of Science Teachers which is on everyone's lips these days. According to Carlson and Daehler (2019), the foundation for PCK is the professional knowledge bases, namely (i) content knowledge, (ii) pedagogical knowledge, (iii) assessment knowledge, (iv) knowledge of students, and (v) curricular knowledge. Central to the model is the three distinct realms of PCK: collective (cPCK), personal (pPCK), and enacted PCK (ePCK). For these realms of PCK, the grain size (discipline-specific, topic-specific, or content-specific) can vary. cPCK is to be seen as explicit knowledge that has been articulated and shared publicly among researchers and science teachers. When it comes down to pPCK as a repertoire for teaching, it is strongly influenced by the learning context as well as by the teacher's amplifiers and filters. Behling et al. (2022, 15) identified “knowledge-based reasoning about relevant elements regarding students’ language proficiency” as an amplifier and filter lying between pPCK and ePCK concerning teaching scientific language. pPCK is shaped by the professional knowledge bases, by cPCK, and by a teacher's personal experience, and influenced by others, e.g., peers and students. ePCK is to be seen as a fragment of pPCK that is used in the cycle of planning, carrying out, and reflecting a particular lesson in a particular context to particular students and aims to achieve particular student outcomes and thus as “tacit knowledge in action” (Alonzo et al., 2019, 284). But the flow of knowledge of the different realms of PCK as well as the teacher's professional knowledge bases cannot be considered as going in only one direction rather than the different types of knowledge influencing each other (Carlson and Daehler, 2019).

Since PCK is tacit and not used consciously by the teachers (Kind, 2009) and therefore remains a rather theoretical construct, Loughran et al. (2000, 2001) have made several attempts to investigate science teachers’ PCK. As they recognize that teachers have difficulties articulating their knowledge about their practice, Loughran et al. (2004, 2006) end up constructing Content Representations (CoRes) as a research tool to capture and portray science teachers’ pPCK and therefore transform it into cPCK. These CoRes consist of several different questions concerning different aspects of PCK and were used within a workshop for science teachers to initiate the discussion about teaching a particular topic to elicit the topic-specific pPCK. However, in this way only the reported pPCK of teachers can be captured but not the ePCK, which in many cases is found to be lower than the reported pPCK (Alonzo and Kim, 2016; Mazibe et al., 2020).

Teacher knowledge of teaching (scientific) language

Since it is known that language is essential for teaching and learning (Wellington and Osborne, 2001; Yore and Treagust, 2006; Evagorou and Osborne, 2010; Childs et al., 2015), subject teachers need to know the language of their discipline as well. Therefore, several approaches to teacher knowledge about language have been developed (e.g., Love, 2009; Galguera, 2011; Bunch, 2013; Lucas and Villegas, 2013; Turkan et al., 2014; Fulmer et al., 2021) but most of them in the context of supporting second language learners in content learning.

No approach focuses specifically on the characteristics of the scientific language of chemistry, the Chemish, so far. But since chemistry teachers have to act as linguistic guides for their students to help them acquire scientific language (Laszlo, 2013), they need a special kind of teacher knowledge. This is why, starting from PCK and Pedagogical Language Knowledge which is defined as “knowledge of language directly related to disciplinary teaching and learning and situated in the particular (and multiple) contexts in which teaching and learning take place“ (Bunch, 2013, p. 307), Markic (2017) adapts it to the notion of Pedagogical Scientific Language Knowledge (PSLK) as a chemistry or science teachers’ “knowledge of scientific language related to teaching and learning chemistry, focusing on different scientific topics and contexts” (Markic, 2017, p. 181). PSLK nevertheless remains a rather theoretical construct and less is known about it. Hence, a systematic review (Mönch and Markic, 2022b) is conducted to conceptualize science teachers’ Pedagogical Scientific Language Knowledge. With the help of the framework of the RCM (Carlson and Daehler, 2019), several elements of PSLK are identified and a model of Pedagogical Scientific Language Knowledge of science teachers is developed (Fig. 1 (Mönch and Markic, 2022b, p. 15)). The systematic review reveals that professional knowledge bases, which aim as arrows to the middle of Fig. 1, are an important factor constituting PSLK. To summarize, (i) pedagogical knowledge results in PSLK in the way that it is important to provide a non-threatening and appreciative learning environment and many opportunities for the students to work in collaborative groups, (ii) curricular knowledge is needed to identify important scientific terms and scientific language objectives for the lesson as well as to have an overview of the curriculum regarding scientific language through all grade levels, (iii) content knowledge of scientific language itself as well as the concept behind different scientific terms and relationships between them, (iv) assessment knowledge on how to best assess students’ understanding and usage of scientific language – spoken and written, and (v) knowledge of students in general, more precisely about students’ prior knowledge of scientific language, their difficulties with scientific language and its use and potential roots of these difficulties, differences in students’ abilities across modes of language, differences in students’ language ability across subject areas, and students’ learning progress in language use (Mönch and Markic, 2022b, pp. 8–10). How these teacher professional knowledge bases result in PSLK is influenced by the teacher's amplifiers and filters as well as by the learning context. Regarding the teacher's amplifiers and filters, the teacher's knowledge of the scientific language and the teaching and learning of it is mainly filtered and influenced through their scientific language awareness (Mönch and Markic, 2022b) and thus by recognizing (i) the science teachers’ task to not only teach content but also teach scientific language and (ii) the abstractness of the concepts behind scientific terms, as well as the science teachers’ knowledge of (iii) the characteristics of the scientific language register, (iv) grammar and discourse norms of scientific language, (v) scientific terms and their morphology and (vi) semantic relations between them.

Fig. 1 Model of Pedagogical Scientific Language Knowledge (CC BY MDPI (Mönch and Markic, 2022b, p. 15)).

Regarding the learning context in which teaching and learning take place, chemistry teachers need knowledge about their students’ attributes to be able to adapt a particular lesson to particular students as well as the curriculum material that is available for their teaching. All these beforementioned factors influence science teachers’ PSLK. Through the systematic review, science teachers’ PSLK was found to include eight different elements, which can be found in the inner circle in Fig. 1: knowledge of (i) scientific language role models, (ii) the development of the concept before the development of the scientific language, (iii) making scientific terms and language explicit, (iv) providing a discursive classroom, (v) providing multiple resources and representations, (vi) providing scaffolds for scientific language development, (vii) communicating expectations clearly, and (viii) specific methods and tools for teaching and learning the scientific language (Mönch and Markic, 2022b).

Parallel to the named model of PSLK, Seah et al. (2022) lately propose a Language-Related Knowledge Base for Content Teaching (LRKCT) focusing on the discipline-specific language of a subject. LRKCT includes “knowledge of language, knowledge about language, knowledge of students and pedagogical knowledge (with a sub-component knowledge of the role of language) (Seah et al., 2022, p. 5). Seah and Silver (2022) build on the LRKCT framework when investigating science teachers’ language-related knowledge during an intervention aiming at raising science teachers' language awareness (TLA). Within their study, they can identify components of declarative Teacher Language Awareness (dTLA), more specifically twelve components of knowledge about (scientific) language (KAL) and seven components of knowledge about students’ language (KS) on three different levels: (i) the system-level, understanding scientific language as a system, (ii) the text-level, referring to particular text-types, and (iii) the lexicogrammatical-sentence-level, which refers to the meaning, features, and functions of different terms, as well as their role in sentence construction (Seah and Silver, 2022, p. 32). Furthermore, they investigate the procedural dimension of TLA (pTLA) in which KAL and KS are put into teaching practice. Here Seah and Silver (2022, p. 33) can identify six distinct ways: (i) use of metalanguage, (ii) activity design, (iii) task scaffolds, (iv) use of student writing as resources for teaching and learning, (v) use of visual aids to facilitate learning about language, and (vi) feedback for students.

Within the systematic review, only discipline-specific elements of PSLK are identified. Finally, one limitation of the systematic review is that it mainly consists of case studies so there is hardly a possibility to gain insights into the common practice of teaching scientific language. Additionally, the elements that are identified lack depth of content and do not focus solely on Chemish.

Goals and research question

Since the approach of Seah and Silver (2022) focuses on the knowledge acquired through an intervention and the model of PSLK needs to be validated and further elaborated, within the present study, we aim to validate the model of PLSK and elaborate on chemistry teachers’ actual personal Pedagogical Scientific Language Knowledge in more detail and therefore provide it as collective PSLK to the community. Another aim of the present study is to ascertain whether PSLK is only discipline-specific or if there is topic- or content-specific elements as well. The research questions guiding the present study are:

RQI: Can the factors influencing PSLK (teacher professional knowledge bases, teacher's amplifiers and filters, learning context) be described in more detail? If so, how?

RQII: What are the different elements (the ones from the systematic review (Mönch and Markic, 2022b) and new ones) of Pedagogical Scientific Language Knowledge of chemistry teachers comprised in detail?

RQIII: How can the elements of Pedagogical Scientific Language Knowledge be characterized in terms of their grain size (discipline-specific, topic-, or content-specific elements)?

Methodology

Research instrument and data collection

Since the approach of Loughran et al. (2006) has been taken up by many scholars to access science teachers’ PCK (Padilla et al., 2008; Chapoo et al., 2014; Chordnork and Yuenyong, 2014; e.g., Morton, 2016; Lawrie et al., 2019), the CoRes approach also seems to be promising to systematize PSLK. Therefore, an interview study along the lines of the CoRes approach is conducted, adapting the questions to the context of teaching scientific language. Contrary to the CoRes approach (Loughran et al., 2006), we do not conduct group interviews for two reasons: (i) we do not have the same setting as we do not provide teacher workshops during which the group interviews could take place and (ii) when the interviews are conducted in summer 2021, the regulations due to the covid pandemics do not allow to meet in person. Consequently, the interviews are conducted and recorded via Zoom. One could now note that group interviews could also be conducted online, but it did not seem possible for us to create an atmosphere online within which teachers would be comfortable discussing their knowledge and teaching practice of teaching Chemish with one another since one's teaching is a very sensitive topic. All interviews are conducted in German.

This interview study is non-interventional. The Declaration of Helsinki is followed. All participants are informed about their assured anonymity, why the research is being conducted, and how their data is going to be used. Informed consent is obtained from all subjects involved in the study. Furthermore, all participants of the study are older than 18 years of age, which means no further permission from a parent or guardian is required for their participation in the study. According to German legislation, no further ethical approval is required.

After a short “warm-up phase” in which the demographic data is gathered, the semi-structured interviews are divided into two parts:

(i) The first part is initiated by the open question “How do you teach scientific language in chemistry class? Please explain.” This question intends to stimulate a narrative passage. During this part, participants are only encouraged to talk more about their teaching practice of teaching Chemish, no further questions are asked here. When participants finish the first narrative passage, questions that come up during the first part are asked then.

After clarifying questions, the second part is guided by open questions. These questions are derived from the CoRes by Loughran et al. (2006) and adapted to the context of teaching scientific language. The list of guiding questions for the second interview part is to be found in Table 1. There is no particular order to ask these questions as in the sense of intensive interviews (Charmaz, 2014) it is important to remain flexible and to adapt to the language used by the interviewee. For example, questions may have already been answered during the first part of the interview, which can be referred to again in the second part of the interview. Since teachers’ knowledge and teaching practice are very sensitive topics, special care has been taken not to formulate questions in a suggestive or judgemental manner. This requires a particularly sensitive approach on the part of the interviewer.

Table 1 Interview guide (translated from German)

Why is it important for students to learn the scientific language?

What should the students learn when it comes to the scientific language?

How does students’ prior knowledge influence the teaching of scientific language?

Are there other factors that (can) influence the teaching of scientific language in chemistry classes?

Why is scientific language a challenge for students?

What are the ways to diagnose students' understanding/misunderstanding when teaching scientific language?

In what way do you consider scientific language during the planning or implementation of your lessons? Also concerning certain groups of students?

Are there particular teaching methods you use for teaching scientific language? Which are the reasons for using them?

What have you already tried out while teaching scientific language? What has worked well, and what has not worked well?

You as a teacher know more about scientific language than your students need to know. Is this a challenge for you sometimes?

Thinking back to your time as a teacher until now, how does your teaching scientific language have changed?

Is there anything you may not have thought about before but during this interview?

In summary from your point of view, what are the most important points to consider when teaching scientific language?

What else would be helpful when teaching scientific language? What else would help when teaching scientific language?

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Data analysis

The audio files of the interviews are transcribed verbatim using a transcription guide (Kuckartz, 2010, 2018). Since there are no known approaches to investigating chemistry teachers’ PSLK and it has been a mostly theoretical construct so far, an open approach is chosen to excerpt the maximum information possible. It is systematized through deductive and inductive coding, using the software MAXQDA.

Since the aim of the study is to validate the model, but also to identify elements that are not yet known, and knowledge is characterized by complex interrelationships, the Grounded Theory approach (Strauss and Corbin, 1990) was chosen. The approach focuses on inductive coding in the first step to allow for new findings to be made. For us, coding deductively from the beginning entailed the risk of not remaining open to discovery and not being able to identify possible new elements. However, according to Strauss and Corbin (1990), one is always influenced by previous knowledge and in this case the previous development of the model of PSLK may have impacted the coding process and thus the reliability of the results.

For the analysis, in the first step of open coding, the data is summarized, labelled, or paraphrased. In the step of axial coding, codes focusing on the same topic are grouped into categories and connections between codes are drawn. In this step, some of the codes can already be grouped into the elements influencing and constituting PSLK which were identified in the systematic review (Mönch and Markic, 2022b), and therefore deductive coding is applied. In the last step of selective coding, the findings are then grouped back together and integrated into the model of PSLK. The individual steps are validated communicatively within a group of chemistry teacher educators and chemistry teachers (Swanborn, 1996).

The Grounded Theory approach allows that these three steps are not worked through one after another, but that the steps overlap or are worked through again. This means that collected data is selectively and repeatedly coded from different perspectives or regarding different questions. Comparisons are constantly made between different interviews to be able to fully represent the individual aspects in the sense of axial coding of a category. In the sense of theoretical sampling, this means that data collection, coding and analysis take place simultaneously, so that a theoretical saturation can be achieved, and further data is only evaluated as needed in the sense of the current research question.

Sample

19 chemistry teachers participated in the study. As we conduct the interviews online, chemistry teachers from five different federal states in Germany are interviewed. That means the curriculum they use to teach depends on the federal state they teach in and is also dependent on the type of school they teach in. The teachers are between 27 and 55 years old (M = 35.3, SD = 7.2), twelve identify themselves as female and seven as male. At the time of the interviews, the teachers already have between two to 16 years of teaching experience as chemistry teachers (M = 7.3, SD = 5.0). Out of 19 teachers, 15 teach in lower and upper secondary, three only in lower (grade 5–10, age 10–15 years), and one only in upper secondary schools (grade 11–13, age 15–18 years).

Results

Since this study aims to describe the elements of PSLK in more detail, identify potential new elements of PSLK (RQII), and potentially gain new insights into the factors influencing PSLK (teacher professional knowledge bases, teacher's amplifiers and filers, and the learning context) (RQI), the results presented in the following subsections can be seen as an extension to the findings on PSLK already obtained in the systematic review (Mönch and Markic, 2022b). According to the findings, the model of PSLK has been revised (Fig. 2, newly identified elements are coloured in dark blue). In terms of the second research question, two additional elements are identified, i.e., knowledge of the motivation when learning scientific language as well as knowledge of lesson preparation and follow-up and therefore added to the PSLK elements in the inner circle in Fig. 2. Regarding teacher professional knowledge bases (aiming as arrows to the middle of Fig. 2), teacher's amplifiers and filters (outer circle in Fig. 2), as well as the learning context (middle circle in Fig. 2), all sub-elements are displayed in Fig. 2. In the following, all elements of PSLK are described in more detail. Where appropriate, examples from the interviews are used and referred to with the code LX/Y (whereas X stands for the transcript number and Y for the respective paragraph) to illustrate the findings either in text or can be found in numerical order in the Appendix (see Table 2). These examples have been translated from German to English by the authors. The translations have been validated by two independent chemistry educators. The first translated the examples from German into English, and the second translated the examples from English back into German. The examples were used only when the translations matched.

Fig. 2 Revised model of Pedagogical Scientific Language Knowledge.

Teacher professional knowledge bases

(i) Curricular knowledge. Within the systematic review, we identified knowledge of the curriculum and (alternative) materials which serves to identify core scientific terms, define language objectives, and analyse material, as well as vertical curricular knowledge which serves to identify key scientific terms that are important across multiple grade levels and to be able to identify terms students’ should already know (Mönch and Markic, 2022b). Through the interviews, it appears that the focus for teaching Chemish is on vertical curricular knowledge, i.e., on identifying and omitting scientific terms (L16/42), as well as on connecting prior knowledge of scientific terms acquired in lower grades with newly acquired knowledge (L18/40). Since the curricula in Germany are spiral curricula, an overview of potential different meanings of terms through grade levels and the connectivity of terms to other terms is helpful for chemistry teachers (L9/54).

In addition to the vertical curricular knowledge, we found in the interviews that horizontal curricular knowledge is mentioned as needed to make connections to other subjects to distinguish the meaning of the term within chemistry from the meaning of the term in another subject or to show that the meanings are the same.

Teacher amplifiers and filters

(i) Scientific language awareness. In general, almost all teachers characterized Chemish at the beginning with scientific terms when asked to explain their teaching practice of Chemish. During the interviews, some teachers include more and more other characteristics of Chemish (e.g., non-technical terms, symbolic language, syntax/text types, derivates from Greek/Latin). Others are very uncertain about what belongs to Chemish or use Chemish imprecisely or technically incorrectly during the interviews. Only seldom are all characteristics of Chemish named. One teacher didn’t even think about Chemish beforehand (L4/120). Additionally, chemistry teachers report that Chemish is so natural to them that they can’t always identify terms unknown to students.

Taking their second teaching subject into consideration, teachers who teach a language are more language aware and therefore consider Chemish more actively. Additionally, five teachers first state that students’ general language competencies are important and therefore need to be taken into account before considering Chemish (L10/2).

The results bring more detail in the sub-elements of scientific language awareness:

• awareness that teaching scientific language is a task of chemistry teachers: Chemistry teachers acknowledge that they need to teach Chemish because the content is inextricably bound to language (L16/28) and Chemish is like a foreign language to students. Additionally, Chemish is part of the curriculum and therefore must be taught to students.

• awareness of grammar and discourse norms of scientific language: Chemistry teachers report explicitly focusing on these when teaching Chemish, mainly on different text types, mathematical elements, pictures from experimental setups, or tables, as well as on passive voice, lab jargon, and the accurate separation of different representational levels (L11/7).

• awareness of scientific terms and their morphology: Knowing the origin and structure of scientific terms help chemistry teachers to derive the scientific terms and explain the systematic structure of terms to students as well as to dissect new scientific terms with students. Furthermore, chemistry teachers report that it is helpful for students to introduce genus and plural of scientific terms.

• awareness of semantic relations between scientific terms: Semantic relations are important to know for the teacher to draw interconnections as well as to be aware of which interconnections students are already or not yet able to make based on their knowledge, and that chemistry teachers accordingly use Chemish that is adequate for the students’ concept. However, chemistry teachers report it to be difficult for them to recognize that students haven’t heard of scientific terms before or only heard of them once and have not yet internalized the concept (L18/48).

• awareness of the difference between the scientific language register in comparison to other language registers: Teachers state that the scientific language register of Chemish is very precise, unambiguous, and an international language and thus differs from the academic language register and the everyday language register. Hence, an ambiguity of some terms results. Therefore, teachers report that the different registers must be used accurately and separated from each other. Additionally, communicating different representational levels requires different accuracies and possibly also different language registers.

• awareness of the abstractness of the concepts behind the terms: Some concepts are very abstract and thus very difficult for students to understand and express linguistically. Then again Chemish plays a crucial role since the imagination is formed only through the language and the imagination is expressed through the language. As stated in the interviews, models are often used but limitations must be openly discussed.

(ii) Experience. From the interview, it is obvious that teachers’ experiences as students and on their way of becoming and while being teachers act as amplifiers and filters when teaching Chemish.

• oneself as a student: Teachers adapted the methods of their chemistry teachers. Some methods and tools were perceived as not helpful. Some methods and tools were perceived as especially positive.

• teacher training: Chemistry teachers explain that by experience in internships they became aware that Chemish is an obstacle for many students. They get to know different methods and tools. Trying out these methods and tools in internships and revising and creating authentic material was helpful. By doing so, chemistry teachers first get to know the advantages and disadvantages of the methods and tools and develop a feeling for the dose of Chemish.

• working as a teacher: It becomes clear that time, i.e., professional experience, also strongly influences teaching Chemish and expectations towards Chemish in class. It is stated that at the beginning of the teaching career, the focus was less on Chemish caused by new work. An explicit focus on Chemish in teaching and in reflecting on one's own Chemish use is then laid after some time (L16/46). They become more confident in teaching Chemish and using methods and tools for teaching Chemish over time. More experienced chemistry teachers report that they no longer focus explicitly on Chemish but consider it intuitively.

Learning context

(i) Student attributes. Students’ attributes are an upcoming topic in the interviews as they influence the way of teaching Chemish (L13/91). In detail, the following insights have been gained through the interviews:

• Students’ prior knowledge of and about scientific language is reported to influence the level of Chemish to be taught and not to overwhelm students with Chemish or to make students feel anxious. Therefore, chemistry teachers sum up that the diagnosis of students’ prior knowledge is crucial.

• Students’ difficulties with scientific language and its use are reported to occur mainly when addressing different representational levels, the syntax, and discourse norms of Chemish, or command words.

• Students’ abilities across modes of language are described generally to be better in oral modes, i.e., listening and speaking, than in written modes, i.e., reading and writing.

• Students’ learning progress in language use is important to consider when adapting the level of Chemish.

• Students’ experiences and cultures are mentioned by teachers not only to be important for being able to connect to students’ experiences and use their home language but also to help the teacher to understand the importance of chemistry, and thus Chemish, in students’ culture. Additionally, this knowledge aims to adjust the expectations towards the Chemish level of their students (e.g., non-chemical career aspiration (L12/26) or their general linguistic abilities). Chemistry teachers discuss that students’ general language proficiency influences the way of teaching Chemish as a certain level of (academic) language proficiency is needed as a basis for Chemish. Furthermore, students’ native language can serve as a frame of reference to better understand Chemish but at the same time, it is difficult since students sometimes do not have concepts of terms in their native language and therefore cannot rely on their native language.

(ii) Curriculum material. As already found (Mönch and Markic, 2022b), curriculum material influences the way of teaching Chemish since the teacher must be knowledgeable of how Chemish is used therein. In Germany, schools decide on which textbook they want to use and thus buy it for their classes. Chemistry teachers see problems in the overload of scientific language and the usage of other scientific terms or definitions than they want their students to know. Thus, chemistry teachers must either prepare material themselves, which is often a time problem, or draw students’ attention to differences and discuss these with students.

(iii) Internal school curriculum for chemish. An internal school curriculum, in which scientific terms and definitions of these terms (within chemistry and other subjects in which scientific terms also play a role) are prescribed, is reported to be helpful. Thus, teachers can rely on scientific terms and other scientific language objectives set in the internal school curriculum and this eases their work (L1/2.1) but also helps students when the terms are used consistently by teachers.

(iv) Colleagues. Colleagues turn out to be a very important factor in teaching Chemish since communication and close cooperation between chemistry teachers and a consensus on which scientific terms should be used facilitates Chemish teaching, especially when teaching the same grade. They stated that they see the need to discuss the Chemish level as well as scientific terms students already know when handing over a class. An exchange between colleagues is beneficial as it allows teachers to try different approaches and to directly consider each other's experiences regarding students’ difficulties with Chemish.

However, colleagues are described also as an obstacle since they can have a lack of scientific language awareness, see no need to agree on scientific terms, or there is no exchange between each other.

(v) School organization. Chemistry teachers state that if lessons are early in the morning or late in the afternoon, focusing on Chemish is harder, especially for students. Additionally, the type of school influences Chemish teaching and learning because there might be different levels of differentiation within a class. Additionally, the organization around chemistry lessons influences Chemish teaching and learning: in some schools, no homework can be given and thus chemistry is only taught within the lessons, in some schools, chemistry is only taught for half a school year every year with half a year pause between.

Pedagogical Scientific Language Knowledge

(i) Knowledge of scientific language role models. The knowledge of scientific language role models includes three aspects, the last of which emerged in the interviews:

• knowledge of the chemistry teacher serving as a scientific language role model: Teachers report of consciously using Chemish, always using scientific terms correctly and always the same ones (L1/2.2). The casual use of Chemish and its explanation is reported to facilitate understanding (L7/2). Being conscious of the role as a scientific language role model helps the teacher to also become aware of expectations of the students' Chemish use (L16/48). However, chemistry teachers report that they cannot always monitor their Chemish usage and therefore communicate to students that a chemistry teacher can also make mistakes.

• knowledge of students serving as scientific language role models: Chemistry teachers report that groups foster communication in Chemish since the hurdle is lower than speaking in front of the whole class. Such procedure functions as a controlling instance since students within a group need to build a mutual understanding (L10/44). Furthermore, chemistry teachers make use of students as scientific language role models by discussing students’ answers.

• knowledge of other instances serving as scientific language role models: Since teachers know that students may adapt the scientific language unreflectively (L2/34), chemistry teachers draw on their knowledge of how to use other instances acting as scientific language role models to make students aware of the incorrect and in some cases deliberately wrong Chemish use.

(ii) Knowledge of providing a discursive classroom. The focus here is on the importance to create a language-rich and discursive learning environment to reach a process of enculturation in chemistry (L11/11).

This PSLK element contains the following sub-elements:

• knowledge of providing opportunities for students to practice scientific language: Chemistry teachers often practice collaborative group work in their classes. Students are found to be more likely to contribute to the lesson discussion when they had the opportunity to talk with their peers first (L12/12).

• knowledge of incorporating multiple dimensions of language: Talking Chemish, talking about Chemish, and writing and reading Chemish is reported to be very important for students’ Chemish development. Chemistry teachers combine different dimensions of language, use models or graphics and let students draw or sketch to further students’ understanding.

• knowledge of asking questions: Chemistry teachers report using questions to encourage students to use Chemish and by doing so to (i) monitor students' understanding and (ii) encourage students to think.

• knowledge of using mistakes as learning opportunities: Creating an appreciative and non-threatening learning environment is described as crucial for mistakes to be seen as learning opportunities and to reduce scientific language anxiety on the side of the students.

One sub-element identified within the systematic review (Mönch and Markic, 2022b) could not be sufficiently substantiated in the interviews: knowledge of negotiations of term meanings. In the systematic review, we identified that negotiations of term meanings and thus creating mutual understanding can foster students’ understanding in three ways: when (i) students make sense of term meanings individually, (ii) negotiations take place among students in the group, and (iii) when negotiating term meanings in the whole class (Mönch and Markic, 2022b).

(iii) Knowledge of communicating expectations clearly. Chemistry teachers express that expectations are transported implicitly since the teacher acts as a scientific language role model. Communicating expectations clearly also means for chemistry teachers in this study to point out when it is an exercise situation in which students are allowed to make mistakes and when it is an evaluation situation in which students must be very careful about their use of Chemish. Command words are named explicitly for students to correctly assess the requirements of a task and for chemistry teachers to set tasks (L3/55). Chemistry teachers emphasize that it is important to disclose the criteria for assigning grades at the beginning of the school year and to hand out an expectation horizon for grading regarding Chemish.

(iv) Knowledge of providing multiple resources and representations. Providing multiple resources and representations is stated as a chance to minimize the abstractness of concepts behind scientific terms, especially on the sub-microscopic level and to help students form a more holistic idea of a concept, especially if connected to everyday life. Within the interviews, chemistry teachers mainly mention the use of visualizations to foster students’ understanding (L18/28), e.g., to connect scientific terms with pictures or drawings to create visual anchors. Moreover, chemistry teachers report using mnemonic bridges, pictograms, symbols, comics, models, videos, animations, and drawings. With the help of role plays, animisms, anecdotes, and analogies, chemistry teachers make a connection to students’ everyday life. Chemistry teachers state that caution is advised to avoid misconceptions or misunderstandings (L16/12) and not to use them unintentionally. Thus, a meta-discourse is described as helpful to discuss limitations.

(v) Knowledge of the development of the concept before the development of the scientific language. Knowing that slowly abstracting from everyday language on a phenomenological level and thus avoiding scientific language at this stage can lead to misconceptions about scientific language after conceptual understanding appears to be an important point (L19/2). According to the teachers, attention must be paid to the differentiation from and the interconnection with other terms and concepts. As a result, chemistry teachers state that not every lesson focuses on Chemish, and sometimes Chemish has to cut back, e.g., in favour of an experiment, but then has to be taken up again in the next lesson. Other ways to achieve conceptual understanding on the part of students are to use animisms, analogies, and models (compare the knowledge of providing multiple resources and representations).

Teachers also indicate that understanding a concept is inextricably linked to the right use of Chemish. Thus, teachers state that if students can use Chemish correctly, it can be concluded that students have understood what they are talking about.

(vi) Knowledge of making scientific terms and language explicit. Chemistry teachers draw students’ attention to scientific terms by discussing their morphology, e.g., prefixes, suffixes, and root words, pointing out the genus therefore always use the article when mentioning a term, and the plural of scientific terms, the meaning of lower and upper case in symbolic language, as well as to interconnect different terms and concepts. Discussing scientific terms also serves to help students develop their metalinguistic skills (L19/34). Besides pointing out Chemish orally, chemistry teachers report making Chemish explicit by writing down important scientific terms, not only in students’ notebooks but also visibly in the classroom. In addition, chemistry teachers report paying attention to the clear distinction of the use of a scientific term in the chemical context as opposed to the use in other language registers. Humour is also used to make students aware of imprecise Chemish use. Knowing about lab jargon and thematizing it is seen as fruitful to making conventions of Chemish explicit and avoiding misunderstandings. Chemistry teachers place particular emphasis on separating representational levels linguistically and always make students aware of which level they are on at any given moment. Therefore, gestures, facial expressions, and intonation are used supporting.

Different scientific text types are also thematized, introduced in small steps, and requirements are made explicit. Chemistry teachers point out that text comprehension strategies which are also practised in other subjects cannot necessarily be relied upon.

(vii) Knowledge of specific methods and tools for teaching and learning scientific language. Chemistry teachers mention different strategies for teaching and learning Chemish which can be divided as followed:

• knowledge of introducing Chemish: Chemistry teachers report to introduce scientific terms and text types gradually and dosed. Lab reports can be introduced by starting to let students describe a picture and point out the difference to an interpretation and then slowly introducing one step of the lab report after another.

• knowledge of practising Chemish: To repeat key scientific terms, chemistry teachers report letting students define them but giving all students the same chance to catch up on the content of the last lesson. Another way is having a ‘chemist of the week’ at the beginning of every lesson who summarizes the last lesson using scientific terms. Some teachers report designating ‘Chemish guards’ to let students monitor the Chemish use of the teacher and students and provide feedback at the end of the lesson. Chemistry teachers report in the interviews that they use memory with pictures and names and structural formulas, card games, and crossword puzzles, and often use digital resources like Quizlet, learning apps, and Kahoot for quizzes, drag and drop tasks, and cloze texts. However, cloze texts are seen critically as it checks mainly the mastery of grammatical structures. Another possibility chemistry teachers in this study report is to let students draw and then explain their drawing orally or by writing a text. Concept maps, graphic organizers, and mind maps are also used to help students draw interconnections and point out differences between scientific terms and put them into words. To initiate practising Chemish, chemistry teachers often use students’ statements or artefacts, advertisements, newspaper articles, songs, and videos and then have students evaluate the Chemish use and improve it if necessary. When practising reading scientific texts, chemistry teachers report that they start reading texts together and chemistry teachers clarify unknown scientific terms directly with students.

• knowledge of summarizing Chemish: The most common method named by chemistry teachers in this study to summarize scientific terms is to use a glossary. The glossary can include a scientific term and its definition, but also examples, mnemonic bridges, pictures, and drawings. Some teachers also include articles and plurals for nouns, irregular verb forms, and comparatives of adjectives in the glossary. When chemistry teachers do not use a glossary, they use memory sentences or definitions. Also here chemistry teachers state to use concept maps to have an overview of and highlight connections and differences between scientific terms or to have them serve as visual anchors. Visual anchors are as well used for important terms or lab equipment.

• knowledge of monitoring students’ use of Chemish: Chemistry teachers state that they continuously monitor students’ use of Chemish by listening to students during group work or taking a look at student artefacts as this often reveals whether students are using scientific terms in the right context. Another way stated by chemistry teachers to monitor whether students use Chemish correctly is to let them explain scientific terms. This can be done in two ways: (i) have individual students explain in plenary or (ii) have students explain scientific terms to each other and have the task of giving each other feedback. The other way round, students can be provided with an explanation and have to write down the belonging scientific term.

(viii) Knowledge of providing scaffolds for scientific language development. Chemistry teachers know the lower the grade level the more scaffolds are needed but the number of scaffolds also depends on students’ attributes. The following scaffolding strategies regarding Chemish are indicated by the teachers:

• oral strategies: Questions are often used to help students formulate a correct answer regarding Chemish. Casually mentioning and defining scientific terms is another oral scaffolding strategy.

• visual aids: Chemistry teachers state that letting students draw or sketch helps students to become clearer about the concept and then it is easier for them to express themselves linguistically. Pictures or film bars, which are a sequence of images to represent a process, are used as a formulation aid for talking about a process or writing texts. Regarding students’ difficulties in expressing different representational levels, explicitly indicating on which level one is communicating at the moment (i) with different objects, e.g., by putting on and taking off a scientific hat, (ii) by changing the position in the classroom, or (iii) drawing the Johnstone triangle on the blackboard and indicating on which level they are talking right now scaffolds students precise use of Chemish and their scientific language awareness.

• written strategies: Chemistry teachers report to use (i) text puzzles (a text is cut into sentence strips which must be connected to form a coherent text), (ii) sentence puzzles (sentences are cut into two to three parts and must be connected to form a coherent text, the same sentence parts, e.g., verbs, are coloured the same way to make it easier to find matching sentence parts), (iii) sentence starters (the characteristic beginnings of the expected sentences are given and provide clues about the expected content), (iv) sentence patterns (standardized phrase in which several variations exist for each clause, the verbs and norms are given in fixed forms and by varying the words used students can then create different sentences), (v) concept maps (connections between different scientific terms are represented), (vi) word fields (unordered set of words on a specific topic, can include articles and plurals of nouns and irregular verb forms), and (vii) word rails (list of given words to write a sentence).

(ix) Knowledge of motivation when learning scientific language. Finding the adequate Chemish level (L3/104) as well as focusing on Chemish only after conceptual understanding (L17/58) seems to be essential for motivation. According to chemistry teachers in the study, motivation plays an even more important role at the very beginning of chemistry classes when students have their first encounters with chemistry. Using too much Chemish can then directly discourage students ever to learn chemistry. To keep students’ motivation high, chemistry teachers point out the use of multiple resources and representations, especially the integration of (social) media content to draw connections to students’ interests and thus show relevance for students’ everyday life. Providing scaffolds can also increase motivation. To increase the motivation of particular students, chemistry teachers report selectively picking those who can give a correct answer and thereby also increase their self-efficacy. Moreover, Chemish proficient students can be assigned to less Chemish proficient students to help them with Chemish which also increases the motivation of both and the self-efficacy of Chemish proficient students. Chemistry teachers report that letting students monitor the teacher's Chemish use might increase their motivation as well since students are then able to criticize their teacher. Chemistry teachers also state that by making the purpose and necessity of Chemish transparent students can be motivated to learn Chemish. In general, chemistry teachers state that giving feedback also increases students’ motivation to learn Chemish.

What chemistry teachers address separately is how to deal with students who lack general language proficiency. Keeping them motivated is a much bigger challenge, as students must put much more effort into learning Chemish when they do not even understand the language of instruction (L10/20). Often students having difficulties with language are provided with even more scaffolds and tasks, but the overload of tasks is mainly demotivating them since this often means a lot more work.

(x) Knowledge of lesson preparation and follow-up. Chemistry teachers report that not every lesson focuses on Chemish, as there are many other competencies to be fostered within chemistry class. The following sub-elements are found to be important during lesson preparation and follow-up:

• knowledge about Chemish as lesson objectives: Chemistry teachers stated that the detailed formulation of lesson objectives focusing on Chemish and checklists or glossaries can help to check if the objective has already been achieved during the lesson.

• anticipating students’ prior knowledge and potential problems: Chemistry teachers report to anticipate students’ previous knowledge about scientific terms (i) in chemistry itself, (ii) in other subjects, and (iii) in everyday life as well as which terms students might use to describe a phenomenon that is central to the lesson to counteract problems already in the planning stage (L16/16).

• selecting and defining scientific terms: Chemistry teachers distinguish between important scientific terms that occur more often from unimportant ones by drawing on their curricular knowledge. The principle can be formulated as ‘as little as possible, as much as necessary’ (L16/14). Hence, defining scientific terms beforehand helps chemistry teachers to become knowledgeable of the meaning they want to convey to their students. Additional to scientific terms, non-scientific terms and language can be an obstacle for students and therefore are also considered in planning a lesson.

• checking, adapting, and creating material regarding Chemish: Chemistry teachers report as important to check the material that is going to be used for Chemish but also for consistent use of scientific terms without the use of synonyms. All material is going to be adapted to the Chemish proficiency of the actual class and is therefore influenced by students’ attributes which in turn requires diagnosis (L3/4). The textbook is seldom used. Teachers report sometimes struggling as they do not have enough time to prepare all material themselves. Thus, when using material with other terms it is therefore essential to discuss this issue with students during the lesson, and through that make Chemish explicit and foster students’ scientific language awareness. Teachers also formulate tasks and impulses in advance in order to use Chemish correctly, especially at critical points during the lesson, and also to communicate expectations to students clearly by using command words. Special attention is paid to a uniform layout of working sheets, and when chemistry teachers plan a note on the board they make sure that the focus is directed to important terms.

• reflection on one's own and students’ use of Chemish: In lesson follow-up, chemistry teachers find it helpful for the reflection to check student artefacts for Chemish and take up unprecise use of Chemish in the next lesson.

Regarding RQIII on the grain size of PSLK, it turns out that there are discipline-, as well as topic-, and concept-specific aspects. Since the questions within the interview guide (Table 1) address Chemish as discipline-specific for chemistry, the identified elements can be seen as discipline-specific aspects of PSLK. Within the interviews, it appears that chemistry teachers sometimes give insights into concept- and topic-specific aspects, but these do not occur in an amount that allows them to be systematized. Nevertheless, we are able to gain interesting insights into teaching Chemish within particular topics, e.g., one teacher makes an example of an analogy for learning the electron shell model because the concept is very abstract (L2/32). Therefore, to answer the third research question, PSLK can be seen as including all three different grain sizes. However, when asked to give concrete examples, chemistry teachers often did not have any at hand, since often it happens out of the situation in the classroom (L13/57).

Discussion

A limitation of this study might be that the interviews were conducted only in Germany and the school system as well as teacher education differs in other countries and therefore the PSLK might differ in nuances. By integrating teachers from lower and upper secondary schools and different federal states, we nevertheless tried to explore a broad knowledge and see the chance to make implications.

Through the interviews, we were able to validate the model of PSLK developed in the systematic review (Mönch and Markic, 2022b), investigate elements constituting and influencing PSLK in more detail, and even identify two new elements: knowledge of lesson preparation and follow-up as well as knowledge of the motivation when learning the scientific language. According to the grain size of PSLK, besides discipline-specific aspects as identified within the systematic review (Mönch and Markic, 2022b), a few concept- and topic-specific elements came to light. Since questions in the interview guide (see Table 1) are more general focusing on discipline-specific PSLK, an option to explore topic- and concept-specific PSLK would be to adapt the questions to a specific topic or concept and conduct another qualitative study. Additionally, one must not neglect that teachers’ knowledge is very complex and different components are mutually dependent. Furthermore, other studies investigating the differences between reported pPCK and ePCK brought to light that the reported PCK is often higher and teachers fail to put their pPCK into practice (e.g., Mazibe et al., 2020). On the other hand, some teachers were found to have higher scores in ePCK than in pPCK which might come from the fact that teachers are not used to articulating their knowledge and originates in the tacit nature of this knowledge (Mazibe et al., 2020). It is to question whether this applies also to PSLK in this study and therefore one might also need to investigate chemistry teachers' ePSLK since it encompasses “teachers’ understanding and enactment” (Park and Oliver, 2008, 278). In this way, our attempt to systematize PSLK and identify the factors influencing PSLK (teacher professional knowledge bases, teacher's amplifiers and filters, learning context) could be one step towards the possibility to know what to look for when observing lessons with regard to eliciting teachers’ PSLK and therefore the operationalization of PSLK. Nevertheless, one cannot neglect the fact that the construct of PSLK is very complex as well as the factors influencing PSLK are multifaceted. E.g., horizontal and vertical curricular knowledge is needed when making scientific terms and language explicit for being able to draw connections to terms used within chemistry or other subjects. Once again it became clear that teachers’ knowledge cannot be seen as isolated components but as strongly intertwined aspects that mutually influence each other.

Whether Chemish plays a role at all in teaching and planning lessons depends on the teacher's amplifiers and filters and thus mainly on their Scientific Language Awareness (Mönch and Markic, 2022b). Only if teachers consciously focus on scientific language, they can consider it when planning lessons, during lessons to monitor both their own and the students’ scientific language use and adapt it depending on the situation. We came to notice during the interviews and data analysis that chemistry teachers who are language teachers as well are more aware of Chemish than teachers who do not teach a language. But this is here only in the means of a few cases. In general, research indicates that teachers lack scientific language awareness (Osborne, 2002; Moore, 2007; Gyllenpalm and Wickman, 2011; Nagy and Townsend, 2012; Markic, 2015; Meier et al., 2020; Tang and Rappa, 2021; Mönch and Markic, 2022b). To counteract that issue, scientific language awareness, as well as PSLK, could be fostered already during teacher education to put the focus actively on the language demands of Chemish. As chemistry teachers report, it helped them to have a focus on Chemish and its teaching and learning already during their teacher training program so that they were sensitized about the demands of Chemish and better prepared to teach Chemish when starting their career at school (Mönch and Markic, 2023).

Chemistry teachers who were already sensitized about Chemish through their teacher education program – as they reported – said that they focused on other aspects than Chemish at the beginning of their career as a teacher because there were so many tasks to complete they were not able to consider Chemish additionally. This raises the question of whether a stronger focus on Chemish during the teacher education program can change the teachers’ thinking of Chemish as an additional issue to consider as an integrated aspect that is automatically taken into account in their actions as chemistry teachers. As chemistry teachers report, knowledge of students’ difficulties when learning scientific language develops as teaching experience increases. This has also been shown for teachers’ knowledge of students’ difficulties in science in general (van Driel et al., 2014). In conclusion, the goal of fostering pre-service teachers’ PSLK cannot be to equip pre-service chemistry teachers with all the knowledge rather than to sensitize them to the issue of Chemish to enable them to make their own experiences and therefrom build their own base of PSLK. Therefore, it is necessary to provide pre-service teachers with the possibility to practice in authentic settings.

Comparing our results with those of Seah and Silver (2022), we can conclude that despite using a different framework for systematizing teacher knowledge about scientific language and its teaching and learning results are similar in many ways. However, this study focuses on Chemish and therefore has more Chemish-specific results. Moreover, since the model of PSLK (Mönch and Markic, 2022b) also takes into account the learning context, important insights could be gained regarding its influence on teaching and learning Chemish. Additionally, the focus of this study is on chemistry teachers’ actual PSLK. In contrast, Seah and Silver (2022) explicitly fostered TLA and therefore elements they found are influenced by their intervention. However, all elements Seah and Silver (2022) identified as procedural knowledge are described by the participants of our study as well from which we can conclude that chemistry teachers in our study have a reflective approach to their practice and can also communicate their pedagogical practice.

Since chemistry teachers had difficulties making concrete examples from their lessons, asking them about teaching Chemish in the context of a concrete topic would be helpful. In this way, topic- and concept-specific PSLK could be mapped and with its help, Chemish-supportive and Chemish-sensitive teaching material could be developed.

Starting from the listed results as well as the study by Mönch and Markic (2022a), the issue of differences and overlap of PSLK with other facets of teachers’ professional knowledge needs to be discussed. When we began our research on PSLK, we based it on Shulman's (1987) definition of PCK being an amalgamation of content knowledge (CK) and pedagogical knowledge (PK). We then assumed that PSLK had an overlap with PCK as well as CK but also that some parts of PSLK are independent since it is not only tied to specific content areas. Thus, this showed us that some general knowledge of teaching and learning Chemish must be given. Since there is much research carried out on teachers’ professional knowledge, several different models of pedagogical content knowledge have arisen – most recently the Refined Consensus Model of Pedagogical Content Knowledge (Carlson and Daehler, 2019). We were drawing on this model to carry out our research since it respects different grain sizes of PCK and thus addresses our observation within our first assumption that PSLK is not only tied to specific content areas but parts of PSLK also focus on the characteristics of Chemish in general and therefore are universally applicable to the discipline. Thus, we can say that the research we carried out on PSLK so far has shown us that PSLK can be seen as (i) a part of a chemistry teacher's PCK focusing on teaching and learning Chemish for different topics and contents (topic- and content-specific) and (ii) as a part of chemistry teacher's PCK which is general for teaching and learning Chemish for different topics and grade levels (discipline-specific). Furthermore, PSLK is found to be influenced by all the teacher professional knowledge bases, the learning context and the teacher's amplifiers and filters (see Fig. 2) and therefore is very complex.

Conclusions and implications

As we found, similar to the findings of the systematic review (Mönch and Markic, 2022b) and other studies (Markic, 2015; Meier et al., 2020; Tang and Rappa, 2021), that chemistry teachers mainly focus on scientific terms when talking about Chemish but not, e.g., on the syntax or the symbolic language, the PSLK seems to be very heterogeneous. One conclusion that can be drawn therefrom is that PSLK needs to be fostered in general. Therefore, it is even more important to raise the scientific language awareness and the PSLK of university teacher educators since they also act as scientific language role models for their pre-service chemistry teachers. It is found that pre-service chemistry teachers lack knowledge of the scientific language and its teaching and learning (Mönch and Markic, 2022a). Regarding the complexity of elements influencing and constituting PSLK, it seems important to focus on both, PSLK acquisition and PSLK application in teacher education since PCK acquisition and enactment are found to be two interdependent factors and especially the enacted PCK depends on the learning context (Park and Oliver, 2008). Therefore, the model of PSLK (Fig. 2) can be used to guide professional development. Another crucial point is to integrate Chemish as well as its teaching and learning into the curriculum at the university. Thus, the focus in university teacher training could be put specifically on teaching and learning Chemish and including all teacher professional knowledge bases. As teachers reported, it seems important to focus not only on the application of knowledge but also on the sensitization and application of acquired knowledge in authentic settings.

But, where to start? One way to foster pre-service chemistry teachers' PSLK has just recently been proposed (Mönch and Markic, 2023). Since scientific language awareness seems to be the main amplifier and filter hindering (prospective) chemistry teachers to consciously perceive and consider Chemish, sensitizing pre-service chemistry teachers about Chemish and introducing them to the characteristics of Chemish and students’ difficulties with Chemish is the first step. In the next step, pre-service teachers analyse curriculum material in terms of Chemish and learning objectives set in the curriculum. After analysing the curriculum material, pre-service chemistry teachers then are introduced to methods and tools for fostering Chemish and Chemish-sensitive teaching. Thus, they are acquiring PSLK in theory. The work done here was focusing on pre-service chemistry teachers’ knowledge on explicating scientific language, knowledge on methods and tools as well as scaffolding. With this knowledge, they revise the analysed material in a more Chemish sensitive way and thus put their knowledge into practice (Mönch and Markic, 2023).

In addition to scientific language awareness as a basic prerequisite for the formation of PSLK, however, it is not yet known whether some elements of PSLK are more important than others. This could also be a starting point for further research.

As has been shown already for PCK (Kind, 2009) and as becomes evident from the interviews, classroom practice is also crucial to acquire PCK and therefore apply also for PSLK. So, going further than just offering a seminar, a more promising option to foster pre-service chemistry teachers’ PSLK and internalize it would be to put the focus on Chemish during their internships and let pre-service teachers try out methods and tools in practice. Once again, the focus in the internship and accompanying courses could be on methods and tools of teaching Chemish. Pre-service chemistry teachers should be encouraged to try out these methods and tools in practice and therefore shape their PSLK and make methods and tools part of their teaching repertoire. In addition, their mentors’ feedback on their use of Chemish would be crucial to stimulate their reflection on their use of Chemish. However, as became apparent through the interviews, some chemistry teachers are not aware of Chemish and therefore had to be sensitized beforehand as well.

Another point for further work would be that chemistry teachers mentioned that there is hardly any material available that is prepared in a Chemish-sensitive manner, but that most of it is generally language-sensitive with regard to the German language. Thus, topic- and content-specific PSLK could be investigated and with its help and the approach of participatory action research (e.g., Markic and Eilks, 2006), material could be developed that is specifically designed to foster Chemish in a Chemish-sensitive way.

Author contributions

Conceptualization, C. M.; methodology, C. M.; software, C. M.; validation, C. M. and S. M.; formal analysis, C. M.; investigation, C. M.; resources, C. M.; data curation, C. M.; writing – original draft preparation, C. M.; writing – review and editing, C. M. and S. M.; visualization, C. M.; supervision, S. M.; project administration, C. M.; funding acquisition, S. M. All authors have read and agreed to the published version of the manuscript.

Conflicts of interest

There are no conflicts to declare. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Appendix: Interview quotes

 

Table 2 Interview Quotes

Transcript/position	Quote
L1/2.1	“I have also already noticed that this is sometimes difficult with colleagues and that it would be important to agree within the school on terms for specific contexts. Because it super often causes confusion. For example, I also had higher classes that asked me ‘Huh, what's that?’ when I used certain terms. And I said, ‘Yeah, you’ve known that since grade 7, that's this and that.’ And they would say, ‘Oh, that's that!’.”
L1/2.2	“It's important that as a teacher you always use the terms correctly and always use the same terms. Especially if you as a teacher have maybe ten other terms in your head and somehow, well, you just have to consciously decide on one term beforehand and then follow through with it.”
L2/32	“As an analogy to the configuration of the electron shells, there is a parking garage, for example, where the cars drive in bit by bit and the first shell so to speak the first car deck, there only two cars fit in, that is just the smaller one and then comes the next car deck where eight electrons so eight cars can drive in and so the parking garage is just filled up according to certain rules. Just this connection between the parking deck and electron shells and cars and electrons”
L2/34	“For example, CO2, in the news is constantly spoken of CO2, but CO2 is now not a big problem, but carbon dioxide is the problem, so the gas that is created from the CO2 molecule. Of course, there is a connection, but it already starts with the scientific language difficulties, terms that are used wrongly, partly wrongly, by society. And of course, this is imprinted because misconceptions are then simply passed on, which then must be overcome at that moment.”
L3/4	“When I create texts myself, […] you can pay attention to this when constructing sentences, i.e., from easy short word sentences with subject, predicate, object in the lower levels up to grade ten with sentences over three lines with ten subordinate clauses.”
L3/55	“Command words […] really make sense, you notice that very quickly because you can do a lot with them. Even if you make it clear what the difference is between ‘naming’ and ‘explaining’. That is an essential difference, also in the requirements.”
L3/104	“[…] adapt to the students, neither too difficult nor too easy, otherwise the motivation is gone”
L4/120	“These are things that I have never thought about, that's why I asked you earlier, scientific language, what exactly scientific language is. Yes, I haven't really thought about it. For me, these are simply scientific terms […].”
L7/2	“So here now an electron donation takes place, so an oxidation.”
L9/54	“[…] because the oxidation concept is often introduced in three stages. Sometimes reaction with oxygen and then at the end with oxidation numbers and in between as an electron transfer reaction. […] it is easiest and most sensible to introduce it by declaring it only in the tenth grade as oxidation and before that to not speak of oxidation, but for example of a reaction with oxygen […]”
L10/2	”Especially when I think about many methodical things, it is not primarily only chemical knowledge that I need, but also basically linguistic knowledge. That is before I plan a lesson and carry it out, I first think about what are simply also non-linguistic things or non-technical things that can become linguistic difficulties.”
L10/20	“[…] it is also again a quite large motivational effect if one notices that the teacher does not understand what I would like to say. Perhaps the student has understood it cognitively but I as the teacher cannot ascertain it. And the student also notices oneself that there is not any progress or has no self-efficacy, then it's naturally extremely demotivating for the student, and if that happens more often, it's naturally a vicious circle because then the student has less and less desire to get involved at all.”
L10/44	“I don’t just see myself as the key person, but above all, I see the cooperative exchange with fellow students. In other words, always offer discussion phases or occasions for discussion in which they can, of course, express their concerns, their fears, or whatever ideas they have. But they have to bring these into contact or exchange them with others. And they may encounter irritation or even agreement or the complete opposite.”
L11/7	“Then, of course, this whole solubility topic, that you switch quite clearly between the substance and particle level, […] that if, for example, you have drawn something like ethanol, that is already wrong. I didn't draw ethanol, I drew an ethanol molecule.”
L11/11	“I think the point is simply also to speak, yes, that is […] if you want to understand scientific language also as enculturation in a subject, then, of course, you also have to speak, that is then nothing different in language teaching”
L12/12	“[…] sometimes weaker students or those who are less confident are also challenged to discuss in a small group.”
L12/26	“[…] the topic of oxygen affinity. That is, for example, a term where I then also differentiate within the class, where I say ok some want to go in upper secondary, I expect you to work with the term ‘oxygen affinity’, while I say to others, it is enough if you say ‘preference for oxygen’, so to speak, that you find some synonyms.”
L13/57	“It's always hard to make it up as I go along, it's always situations like that when I notice that there's uncertainty somewhere, then I always spontaneously make up something.”
L13/91	“[…] what kind of class I have in front of me, that I just always have to get to know the class for two weeks first and then it develops how and on what level I can communicate with them and it's actually the case that I develop a different concept with each class”
L16/12	“The topic of chemical equilibrium starts with the type of chemical equilibrium, i.e., the chemical equilibrium as a dynamic equilibrium. If one then says, ‘the chemical equilibrium is like a balance’ and compares this with something static, this linguistic formulation can also lead to problems.”
L16/14	“But I don’t let the students learn all the scientific terms, for God's sake. […] I just pick out certain ones that you need for it. […] That means that I clearly start from the principle of what is really relevant for the students. I think this is also an important point with scientific language. So which terms are compatible and which terms do the students need later on when they continue to choose chemistry in upper secondary school. And I focus more on these than on terms that perhaps only appear once.”
L16/16	“[…] if I plan a lesson on electrolysis again because that was such a present example for me from the last school year, then I already have in mind there could be problems that have to do with the scientific language, that means at a particular time in the lesson I have to pay attention to my scientific language and maybe make a note about it in my lesson plan.”
L16/28	“[…] there is the concept of linguistic relativity, so the boundaries of my language are somehow also the boundaries of my world […]”
L16/42	“I have the principle of ‘keep it simple’ in my head and think, ok, if we don’t have certain scientific terms, then we don’t have them, it doesn’t matter, they’ll never need them again anyway.”
L16/46	“But it is nevertheless the case that the more experience I had, the more capacity and time I had to focus more on scientific language.”
L16/48	“[…] the expectations I have of my students are more a reflection of my expectations of myself. So I have to somehow make the students aware that scientific language is really important. And if I don't manage to do that, then I can't expect the students to somehow improve on their own.”
L17/58	“[…] at the beginning of a lesson it is more important to me that they develop the motivation, that they develop a good motivation. And as we progress, it's more important to me that they articulate precisely.”
L18/28	“I try to go through my materials again and see if I […] visualize it in some way. […] I don’t just try one method with an idea of how to do it, but try the second and the third, and see where I notice, okay, something is slowly forming in the student's head, where you can say okay, a certain basic understanding is there.”
L18/40	“But we often have enough points of intersection in the textbooks where you can say, ‘Ah, look, we had that topic, and it's important now because …’”
L18/48	“In the upper school, I sometimes forget that they are just big lower secondary students. That they haven't had it like that and can't make this connection if I don't show them the links. I notice that that's a big point with scientific terms.”
L19/2	“I think, e.g., the first encounter with a scientific term is very, very important for teaching scientific language. And I think you have to think very carefully about how you do that. […] So I think it's always very important to use scientific terms only if the concept has been worked out beforehand, i.e., the content of the term has been worked out very clearly. So I think that's always very important: conceptual content before scientific terms”
L19/34	“What I also find important sometimes is […] that they also understand how such a term originates. So when you get to know a term like lipophilic or hydrophobic, they can also do a translation from a foreign language. So what is actually also important to me, when I introduce scientific terms, is that they are not simply put as a label after the concept has been developed, but that the students can also provide an explanation as to why this particular term and not another one for the same content.”

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Acknowledgements

This research was part of the project “ESTA – Educating Science Teachers for All” that is co-funded by the Erasmus+ Programme of the European Union, under the grant number 609719-EPP-1-2019-1-DE-EPPKA2-CBHE-JP. The European Commission's support for the production of this publication does not constitute an endorsement of the contents, which reflect the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

This publication represents part of the first author's doctoral (Dr phil.) thesis at Ludwigsburg University of Education, Germany. We thank all teachers who participated in the study.

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