Examining the sources of high school chemistry teachers’ practical knowledge of teaching with practical work: from the teachers’ perspective

Abstract

This research aimed to examine the contributions of different sources in developing high school chemistry teachers’ practical knowledge of teaching with practical work in China. The examination was conducted on a theoretical framework in which the conceptualization of PCK and nine sources of teachers’ PCK were involved. Through a questionnaire survey of 323 chemistry teachers, the findings included the following aspects. Firstly, among the nine sources, overall, ‘teaching practices’, ‘curriculum materials’, ‘classroom observations’, and ‘peer coaching’ were recognized as the core sources, whereas ‘learning experience’ was regarded as the peripheral source. Secondly, for the five components of PCK of teaching with practical work, the contributions of the nine sources are different. Thirdly, three sources were found to be significantly different among teachers who have different years of teaching experience: ‘pre-service training experience’, ‘classroom observations’, and ‘peer coaching’. In the last part of this paper, the implications of the findings and the suggestions for the further studies were discussed.

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Introduction

In the school science curriculum, the term practical work, is used to refer to activities carried out in the laboratory or various hands-on activities employed in science teaching (Gott and Duggan, 2007). Due to its close association with experimentation, practical work is usually regarded as a prominent feature of science teaching and learning (Hofstein and Lunetta, 2004; Hofstein et al., 2013). Moreover, as argued by Donnelly (1998), science teachers see the use of practical work as an essential part of what it means to be ‘a science teacher’. In recent years, practical work is often intertwined with inquiry or scientific practice, and performs an important role in the teaching and learning process in the sciences (Wellington and Ireson, 2012). Specifically, practical work plays its educational function at many aspects, including arousing students’ interest in learning science, helping students master scientific knowledge and skills, enlightening students’ scientific habits of mind, training students’ scientific methods, cultivating students’ scientific attitude and values (Abrahams, 2011). It is commonly recognized that effective teaching with practical work is very important for the development of students’ scientific literacy.

Over the past two decades, in the field of chemistry education, many research studies have been conducted on practical work and the topics involved a diversity of areas, including the role and effectiveness of practical work (Thompson and Soyibo, 2002; Taber, 2015), teachers’ understandings and aims about practical work (Lewthwaite, 2014; Yesiloglu and Koseoglu, 2020), students’ perceptions and views of practical work (Lyall, 2010; Sneddon and Hill, 2011), and the instructional strategies for practical work (Tesfamariam et al., 2017; Paterson, 2019). Although the research on practical work has been relatively rich, few researchers have addressed the topic of teachers’ practical knowledge about practical work. Only Wei and Liu (2018) have used single case study to explore an experienced chemistry teacher's practical knowledge of teaching with practical work. As we know, teachers’ practical knowledge, which often refers to pedagogical content knowledge (PCK) (Van Driel et al., 2001), is most closely related to teaching practice (Kind, 2009; Van Driel et al., 2014), it is crucial to study the topic about how to promote teachers’ practical knowledge of teaching in the laboratory so as to improve the quality of chemistry teaching. Given that the acquisition of teachers’ PCK results from a variety of experience during the whole career (Grossman, 1990; Loughran et al., 2006), it is convinced that examining the sources of teachers’ practical knowledge of teaching with practical work can help to construct the effective channels of chemistry teachers’ professional development in the pedagogy of practical work (Hofstein and Lunetta, 2004). In this study, sources refer to the ways that teachers develop their own knowledge. Furthermore, teachers are the person who acquires knowledge. We contended that their own voices on what sources have made to the development of their practical knowledge of teaching with practical work is an irreplaceable indicator that needs to be concerned with. Teachers’ voice can convey what sources are important and they need, which help chemistry teacher educators understand how to support teachers’ professional growth. Hence, in the present study, we have developed a questionnaire to examine the contributions of different sources in developing chemistry teachers’ practical knowledge of teaching with practical work from the teacher's perspective.

Moreover, according to Van Driel et al. (2001), teachers’ experiences play a key role in the development or change of their practical knowledge. The sources of teachers’ access to knowledge may change with the growth of their teaching experience (Loughran et al., 2006). Beijaard et al. (1999) applied story-line method to investigate teachers’ practical knowledge about relevant experiences and events, and revealed the differences in the development of teachers’ practical knowledge in different periods. Fan (2014) also confirmed that for mathematics teachers with different teaching experiences, there are differences in their evaluation of the importance of some sources of teaching knowledge. For the present study, since different teachers have different teaching years, their experience in the practical work can be diverse, so the contributions of different sources in developing their practical knowledge of teaching with practical work might be different. To address this issue, this study was designed to select years of teaching as the variable, investigating the differences in the teachers’ evaluations about the contributions of different sources for teachers with different teaching experience.

Theoretical framework

The conceptualization of PCK of teaching with practical work

In the original conceptualization of PCK, Shulman (1986, 1987) suggested it was this knowledge that distinguished teachers from their non-teaching peers. PCK covers a teacher's understanding of the ways for the transformation of disciplinary content into forms that are comprehensible and accessible to students (Shulman, 1987). According to Van Driel et al. (1998), The two key elements in Shulman's conception of PCK are knowledge of representations of subject matter and understanding of specific learning difficulties and student conceptions. Elaborating on Shulman's work, other scholars have extended the concept by including in PCK some other categories of knowledge (e.g., Grossman, 1990; Magnusson et al., 1999; Banks et al., 2005). Although there is no universally accepted conceptualization of PCK, one consensus has been reached that PCK is rooted in the classroom practice of teachers, that means for the nature of PCK, it is a kind of practical knowledge (Van Driel et al., 2001). Moreover, Carlson and Daehler (2019) developed the Refined Consensus Model (RCM) of PCK. A key feature of this model is the identification of three distinct realms of PCK—collective PCK (cPCK), personal PCK (pPCK), and enacted PCK (ePCK)—which describe the specialised professional knowledge held by multiple educators in a field, to the personalised professional knowledge held by an individual teacher in science, and the unique subset of knowledge that a teacher draws on to engage in pedagogical reasoning during the planning of, teaching of, and reflecting on a lesson. Collective PCK (cPCK) encompasses the knowledge that more than one person possesses, meaning knowledge that is not private, but rather knowledge that is public and held collectively. Personal PCK (pPCK) refers to a teacher's personal knowledge and unique expertise about teaching a given subject area, resulting from the cumulative experiences with and contributions from students, peers, and others. Enacted PCK (ePCK) represents the specific knowledge and skills utilised by a teacher in a particular setting to achieve particular student outcomes. As for teachers’ practical knowledge of teaching with practical work, it has the characteristics of the above three realms of PCK. Based on these considerations, we decided to use the term PCK to refer to teachers’ practical knowledge of teaching with practical work.

As mentioned above, the concept of PCK has been interpreted, explicated and revised by numerous science education researchers (Kind, 2009). Among a variety of PCK models, the model of Magnusson et al. (1999) which consists of five components was proposed specifically for science teaching and has been successfully employed to examine science teachers’ practices (e.g., Chen and Wei, 2015; Fraser, 2016). Abell (2008) also noted that the discrete components of PCK in the model of Magnusson et al. (1999) can serve as useful tools for researchers. Based on this consideration, the model of Magnusson et al. (1999) was adopted. When applying this model to this study, some modifications have been made so as to accommodate to the area of practical work. In the present study, the five components of PCK of teaching with practical work include: (a) orientations toward teaching with practical work, referring to knowledge and beliefs about the purposes and goals for teaching with practical work; (b) knowledge about curriculum and teaching materials of practical work, mainly referring to the amount, arrangement, and features of the laboratory teaching activities in curriculum; (c) knowledge about students’ learning in teaching with practical work, referring to teachers’ knowledge of students’ prior knowledge and ability before a certain laboratory activity and students’ difficulties in laboratory activities; (d) knowledge about instructional strategies for teaching with practical work, referring to knowledge of the specific procedures and strategies for carrying out instruction in laboratory; and (e) knowledge about the assessment in teaching with practical work, involving specific dimensions and methods of assessing students’ learning achievements in laboratory. In the rest of this paper, for the convenience of reading, these five components are briefly called orientations toward practical work, knowledge of laboratorial curriculum materials, knowledge of students’ learning in practical work, knowledge of instructional strategies for practical work, and knowledge of assessment in practical work, respectively.

The sources of PCK of teaching with practical work

In general, teachers’ development of their PCK refers to teacher learning. Teacher learning is the process teachers develop practical knowledge (Carter, 1990), or craft knowledge which was defined as integrated knowledge that represents teachers’ crystallization of wisdom with respect to their teaching practice (Van Driel et al., 1998). According to Grossman (1990), PCK is thought to be generated and constructed through (a) apprenticeship of observation activities whether as a student or student teacher; (b) disciplinary background instruction such as content courses; (c) classroom teaching experience; and (d) teachers’ professional education coursework. Similarly, Haston and Leon-Guerrero (2008) also defined the potential sources of PCK as intuition which is independent creative thought, apprenticeship of observation, method courses which are the required teacher training program education courses and cooperating teacher that refers to contact with a cooperating teacher while student teaching.

In addition, researchers have found some other sources that made to the development of PCK. These sources are suggested as follows: teachers’ daily exchanges with their colleagues (Appleton, 2006), teacher professional journal (Smylie, 1989), Internet (Russell et al., 2009) and curriculum materials (Marco-Bujosa et al., 2017). In short, different kinds of sources for teachers’ development of PCK have been identified, and it is commonly recognized that a teacher's acquisition of PCK could result from a variety of experiences during his/her whole career.

Since the major purpose of this research is to examine the extent to which various sources have made to the development of chemistry teachers’ PCK of teaching with practical work, it is necessary to construct a comprehensive framework that accommodates different sources. In an empirical study, Fan (2014) investigated the sources of PCK of 77 mathematics teachers in three outstanding high schools of Chicago. He constructed a conceptual framework about the sources based on relevant literatures and his personal experience. This framework consists of three main components: (1) experience as learner, referring to teachers’ experience as learners before they acquired formal pre-service training, which mainly happened in formal educational environments like a school; (2) pre-service training experience, including the courses about teaching specific subjects, the educational internship and the general pedagogy courses; and (3) in-service experience, referring to the experience after becoming a professional teacher (Fan, 2014). In the present study, making references to the relevant literature in the development of PCK as well as Fan (2014)'s comprehensive framework about sources, we articulated nine possible sources of chemistry teachers’ PCK of teaching with practical work as follows: (a) learning experience; (b) pre-service training experience; (c) in-service training experience; (d) classroom observations; (e) peer coaching; (f) professional journals; (g) online resources; (h) teaching practices; and (i) curriculum materials. The illustration of these nine sources is presented in Table 1.

Table 1 The illustration of nine sources

Sources	Illustration
Learning experience	Learning experience as a student in the primary and secondary school
Pre-service training experience	Coursework study and internship in normal universities
In-service training experience	Attending continuing education program, conferences, seminars, or workshops organized by the schools, universities, or the government
Classroom observations	Classroom visiting and observation among colleagues
Peer coaching	Daily exchange with colleagues
Professional journals	Reading professional journals about science/chemistry education
Online resources	Learning from online resources such as online training programs and teaching materials
Teaching practices	Personal teaching experience and self-reflection
Curriculum materials	Reading curriculum materials such as textbooks and teacher's guides

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Based on the literature discussed above, the present study aimed to provide empirical data to the following research questions:

(1) In chemistry teachers’ view, to what extent do the nine sources have made to the development of their PCK of teaching with practical work?

(2) Is there any significant difference of the contributions of the nine sources in developing their PCK of teaching with practical work between teachers with different years of teaching experience based on chemistry teachers’ reports?

Research method

This research was a quantitative questionnaire survey. According to Preston (2009), questionnaire survey is a technique for gathering statistical information about the attributes, attitudes, or actions of a population by a structured set of questions, providing broad coverage of populations and enabling us to explore social variations in people's attributes, attitudes, and actions. A questionnaire survey is effective when respondents have knowledge of the topic and they are competent to answer the questions. In the present study, the main focus was on the chemistry teachers’ perceptions of the contributions of different sources to the development of their PCK of teaching with practical work. Therefore, the questionnaire survey was adopted. Next, the instrument, the participating teachers and the procedure for data analysis are described in detail.

Instrument

According to the theoretical framework above, we developed ‘Questionnaire on Sources of Chemistry Teachers’ PCK of Teaching with Practical Work’ as the instrument of this research. The questionnaire was based on the five components and nine possible sources of PCK of teaching with practical work while reference was made to that developed by Fan (2014). To establish the content validity, in the process of developing the questionnaire, four experts and some high school chemistry teachers in Guangzhou had been consulted for their comments on the design of questions. The experts are the professors in the chemistry education area and have experience in questionnaire development. They were asked to give opinions about whether the content of each question was representative of the corresponding construct, wordings of each question was comprehensible to high school chemistry teachers in a Chinese context, and the instructions were clear. This work helped us modify the wordings and the expressions of the questionnaire. For instance, in the initial questionnaire, the illustration of nine sources was not presented. Both the experts and teachers suggested that the illustration should be presented in the questionnaire so that teachers could better understand the sources. Therefore, we followed the advice of the experts and teachers and added the illustration of the sources in the final version.

The questionnaire includes two parts: personal background information and main questions. Personal background information is used to understand and analyze teachers’ responses to the questionnaire. The main questions (questions 1–5) focus on five components of PCK of teaching with practical work. The detailed distribution of questions was shown in Table 2.

Table 2 The distribution of questions in the questionnaire

The Components of PCK	Content of the survey	Questions
Orientations toward practical work	Teachers’ perception about their orientations toward teaching with practical work	1A
	Teachers’ evaluation of the contributions of nine sources in developing their orientations toward practical work	1B
Knowledge of laboratorial curriculum materials	Teachers’ perception about their knowledge of laboratorial curriculum materials	2A
	Teachers’ evaluation of the contributions of nine sources in developing their knowledge of laboratorial curriculum materials	2B
Knowledge of students’ learning in practical work	Teachers’ perception about their knowledge of students’ learning in practical work	3A
	Teachers’ evaluation of the contributions of nine sources in developing their knowledge of students’ learning in practical work	3B
Knowledge of instructional strategies for practical work	Teachers’ perception about their knowledge of instructional strategies for practical work	4A
	Teachers’ evaluation of the contributions of nine sources in developing their knowledge of instructional strategies for practical work	4B
Knowledge of assessment in practical work	Teachers’ perception about their knowledge of assessment in practical work	5A
	Teachers’ evaluation of the contributions of nine sources in developing their knowledge of assessment in practical work	5B

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Each question is divided into part A and part B. Part A is an open-ended question, which inquires teachers’ perception about their PCK in a particular component. The purpose of setting part A is to stimulate teachers’ evaluations about the contributions of nine sources to each of the five components of PCK in part B. Part B includes the nine sources as its items and four responses as its options (4 = very much, 3 = somewhat, 2 = little, 1 = none). The higher the score selected by the teacher, the greater the contribution that the teacher thinks the source has. Questions 2 and 4 are presented as examples of the questionnaire in the appendix. Since teachers’ perception about their PCK in a particular component was not our concern, part A of the survey was not addressed in this work. This paper was mainly focused on the data collected from these part B questions.

Participants

This study was conducted in Guangzhou, the capital of Guangdong province in south China. Guangzhou is a metropolis with a high level of economic development. There are 11 administrative districts in Guangzhou, which can be classified as three types: the urban area, the newly expanded urban area, and the suburban area. In this study, we selected high school chemistry teachers from three urban areas, three newly expanded urban areas, and two suburban areas as the participants. To achieve this goal, the chemistry teaching supervisors† in these areas were commissioned to distribute questionnaires in their own area. It should be noted that the questionnaire filled out by participants was presented in Chinese. The distribution and collection work were carried out from September to October in 2019. When writing this paper, we translated the questionnaire into English. This research went through a rigorous ethics review at our university before data was collected. All of the participating teachers have signed consent letters for completing the questionnaire. From the 350 questionnaires distributed to the teachers in these areas, 27 questionnaires were not completely filled in and were therefore considered invalid. 323 valid questionnaires have been collected with the valid questionnaire recovery rate reaching 92.3%. The background information of the participants is presented in Table 3.

Table 3 Background information of participants

Attributes	N	P (%)
(1) District
Urban areas	92	28.5
Newly expanded urban areas	123	38.1
Suburban areas	108	33.4
(2) Years of teaching experience
1–3 years	69	21.4
4–9 years	81	25.1
10-plus years	173	53.5

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Data analysis

As this study reported on the contributions of different sources in developing teachers’ PCK of teaching with practical work, only the data collected from part B questions (1B–5B) were used. Totally, there were 45 items with a rating of each of the nine sources done for five components. Before the data analysis, I conducted Kolmogorov–Smirnov test to check if the data distribution of the items was normal. The results showed that the data of all items was normally distributed, which met the underlying assumption of parameter tests. Then the construct validation and the reliability of the questionnaire were examined. First, confirmatory factor analysis (CFA) was run by Amos 21.0. The purpose of conducting the CFA is to test the construct validation and confirm that the division of the nine sources in this study is reasonable. All goodness-of-fit indices (χ²/df = 1.684, GFI = 0.926, AGFI = 0.904, TLI = 0.945, and RMSEA = 0.042) indicated good model fit. Additionally, the correlation analysis was run by SPSS 23.0. The correlations between the nine sources are significant. However, the correlation coefficients are relatively small (r = 0.109–0.487), indicating that the sources are relatively independent. Therefore, we accepted the structure of the nine-factor model and divided the sources into nine categories. Second, the Cronbach α coefficient for each source was shown in Table 4, ranging from 0.860 to 0.927, which means this questionnaire had sufficiently high reliability and stability while being used in the data collection (Nunnally, 1978).

Table 4 The Cronbach α coefficient for each source

Sources	Number of items	Cronbach α
Learning experience	5	0.927
Pre-service training experience	5	0.871
In-service training experience	5	0.867
Classroom observations	5	0.865
Peer coaching	5	0.896
Professional journals	5	0.878
Online resources	5	0.898
Teaching practices	5	0.875
Curriculum materials	5	0.860

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The data analysis of this research mainly contained two aspects. The first was to compare the mean score and reveal the relative contribution of nine different sources to the development of teachers’ five components of PCK. In the process of analysis, Bonferroni test was adopted to run the pairwise comparisons (Holm, 1979). To gain a valid result, a reference object was needed at first. In order to classify the contribution of nine factors into different classes, we chose the source that the mean score was in the middle (the fifth one) as the reference to compare with other ones. If the evaluation of some source was significantly higher than the reference, then it belonged to the core source. If the evaluation of some factor was significantly lower than the reference, then it belonged to the peripheral source. The rest of factors and the reference belonged to the secondary source together. Based on the above analysis method, for different components of PCK, the reference sources (the reference score) were likely to be different. The division of core, secondary and peripheral was only for a certain knowledge component, and ‘core sources’ or ‘peripheral sources’ between different components of PCK were not comparable. That is to say, in this study, the core source, the secondary source and the peripheral source are relatively defined, and there are no absolute numerical standards. The second was to select years of teaching experience as the variable by taking into account the answers about background information of the questionnaire, and then carried out one-way ANOVA to test whether there was a significant difference of the contribution of each source between these groups.

Results

Chemistry teachers’ evaluations of the contributions of nine sources to the development of their PCK of teaching with practical work

The contributions of nine sources to the development of teachers’ PCK of teaching with practical work was shown in Table 5. For orientations toward practical work, ‘teaching practices’ (Source H) and ‘curriculum materials’ (Source I) belonged to the core sources; ‘in-service training experience’ (Source C), ‘professional journals’ (Source F), ‘online resources’ (Source G) and ‘learning experience’ (Source A) belonged to the peripheral sources; other sources belonged to the secondary sources. For knowledge of laboratorial curriculum materials, ‘curriculum materials’ (Source I) and ‘teaching practices’ (Source H) belonged to the core sources; ‘in-service training experience’ (Source C) and ‘learning experience’ (Source A) belonged to the peripheral sources; other sources belonged to the secondary sources. For knowledge of students’ learning in practical work, ‘teaching practices’ (Source H), ‘peer coaching’ (Source E), ‘Classroom observations’ (Source D), and ‘curriculum materials’ (Source I) belonged to the core sources; ‘learning experience’ (Source A) belonged to the peripheral source; other sources belonged to the secondary sources. For knowledge of instructional strategies for practical work, ‘teaching practices’ (Source H) and ‘curriculum materials’ (Source I) belonged to the core sources; ‘learning experience’ (Source A) belonged to the peripheral source; other sources belonged to the secondary sources. For knowledge of assessment in practical work, ‘teaching practices’ (Source H) belonged to the core source; ‘learning experience’ (Source A) belonged to the peripheral source; other sources belonged to the secondary sources.

Table 5 The contributions of nine sources to the development of teachers’ PCK of teaching with practical work

Sources	The components of PCK
	Orientations toward practical work	Knowledge of laboratorial curriculum materials	Knowledge of students’ learning in practical work	Knowledge of instructional strategies for practical work	Knowledge of assessment in practical work
Note: (1) for sources, A = learning experience, B = pre-service training experience, C = in-service training experience, D = classroom observations, E = peer coaching, F = professional journals, G = online resources, H = teaching practices, I = curriculum materials; (2) the number in the parenthesis is the mean score of each source.
Core sources	H(3.56)	I(3.57)	H(3.57)	H(3.57)	H(3.55)
	I(3.55)	H(3.55)	D(3.39)	I(3.50)
			E(3.39)
			I(3.35)
Secondary sources	B(3.45)	D(3.38)	F(3.18)	D(3.43)	E(3.38)
	E(3.39)	E(3.38)	C(3.16)	E(3.42)	I(3.37)
	D(3.37)	B(3.37)	G(3.14)	F(3.33)	D(3.36)
		F(3.32)	B(3.11)	G(3.33)	F(3.28)
		G(3.27)		C(3.31)	C(3.26)
				B(3.22)	G(3.26)
					B(3.16)
Peripheral sources	C(3.23)	C(3.20)	A(2.84)	A(2.75)	A(2.69)
	F(3.21)	A(2.83)
	G(3.21)
	A(2.87)
Analysis of variance	F = 50.992, p < 0.001, η^2 = 0.137	F = 55.579, p < 0.001, η^2 = 0.147	F = 51.337, p < 0.001, η^2 = 0.138	F = 67.193, p < 0.001, η^2 = 0.173	F = 66.755, p < 0.001, η^2 = 0.172
	H > D; I > D; C < D; F < D; G < D; A < D	I > B; H > B; C < B; A < B	H > F; D > F; E > F; I > F; A < F	H > F; I > F; A < F	H > F; A < F

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Overall, for all the five components of PCK, ‘teaching practice’ (Source H) was recognized as the core source. Besides, ‘curriculum materials’ (Source I) was another core source for the components of orientations toward practical work, knowledge of laboratorial curriculum material, knowledge of students’ learning in practical work, and knowledge of instructional strategies for practical work. In addition, teachers also evaluated ‘classroom observations’ (Source D) and ‘peer coaching’ (Source E) as the core sources for them to develop their knowledge about students’ learning in practical work. In contrast, ‘learning experience’ (Source A) was recognized as the peripheral source for all the five components of PCK. Besides, ‘in-service training experience’ (Source C) was another peripheral source for the components of orientations toward practical work, and knowledge of laboratorial curriculum material. In addition, teacher also evaluated ‘professional journals’ (Source F) and ‘online resources’ (Source G) as the peripheral sources for them to develop their orientations toward practical work. Moreover, if we take a close inspection at the data presented in Table 5, we can find that even though above sources were steadily identified as being the ‘core sources’ or ‘secondary sources’ across the five components of PCK, their values were different. That is to say, for a given topic, such as practical work in this study, the contributions of these sources were different for different components of PCK of the topic.

In order to examine the overall contributions of nine sources, five components of PCK were integrated into one dimension: the whole PCK of teaching with practical work. For each source, its overall contribution was the mean score of its contribution to the five components of PCK. Once more, the average overall evaluations of the nine sources were reorganized by the above classification to produce the contributions of nine sources to the development of teachers’ whole PCK of teaching with practical work (Table 6). The core sources were ‘teaching practice’ (Source H), ‘curriculum materials’ (Source I), ‘classroom observations’ (Source D), and ‘peer coaching’ (Source E), and the peripheral one was ‘learning experience’ (Source A). Other sources belonged to the secondary sources.

Table 6 The contributions of nine sources to the development of teachers’ whole PCK of teaching with practical work

Sources	The whole PCK
Note: (1) for sources, A = learning experience, B = pre-service training experience, C = in-service training experience, D = classroom observations, E = peer coaching, F = professional journals, G = online resources, H = teaching practices, I = curriculum materials; (2) the number in the parenthesis is the mean score of each source.
Core sources	H(3.56)
	I(3.47)
	D(3.39)
	E(3.39)
Secondary sources	B(3.26)
	F(3.26)
	G(3.24)
	C(3.23)
Peripheral sources	A(2.80)
Analysis of variance	F = 88.792, p < 0.001, η^2 = 0.216
	H > B; I > B; D > B; E > B; A < B

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The comparison of chemistry teachers’ teaching experience with their evaluations of the contributions of nine sources

The average evaluation of chemistry teachers with different teaching experience on the contributions of various sources to the development of their five components of PCK of teaching with practical work were counted respectively. Through one-way ANOVA and subsequent pairwise comparisons (Bonferroni test), the significant differences for each component among three groups were presented in Table 7. It should be noted that to adequately control for possible inflation of Type I error due to multiple tests, the Bonferroni corrected p values were used to indicate significance (0.05/45 = 0.001).

Table 7 Significant differences for each component among teachers with different teaching experience

Components of PCK	Significant difference (sources)	F	Effect size (η^2)	Pairwise comparisons
Note: X = 1–3 years, Y = 4–9 years, Z = more than 10 years.
Orientations toward practical work	Pre-service training experience	12.414	0.072	X > Z
Knowledge of laboratorial curriculum materials	Pre-service training experience	12.786	0.074	X > Z
	Peer coaching	11.490	0.067	X > Y; X > Z
Knowledge of students’ learning in practical work	None	—	—	—
Knowledge of instructional strategies for practical work	Pre-service training experience	16.991	0.096	X > Y; X > Z
	Classroom observations	15.631	0.089	X > Z
	Peer coaching	13.348	0.077	X > Z
Knowledge of assessment in practical work	Classroom observations	14.482	0.083	X > Z

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As shown in Table 7, for orientations toward practical work, there existed only one significant difference among three groups: ‘pre-service training experience’; for knowledge of laboratorial curriculum materials, there existed two significant difference: ‘pre-service training experience’ and ‘peer coaching’; for knowledge of students’ learning in practical work, there was no significant difference among three groups; for knowledge of instructional strategies for practical work, three significant differences were found on ‘pre-service training experience’, ‘classroom observations’, and ‘peer coaching’; for knowledge of assessment in practical work, one significant difference was ‘classroom observations’. The results showed that compared with the teachers with more teaching experience, beginning teachers thought that ‘pre-service training experience’, ‘classroom observations’, and ‘peer coaching’ have greater contributions to the development of their PCK of teaching with practical work.

Discussion and implications

In this study, we have comprehensively and simultaneously examined the contributions of different sources in developing chemistry teachers’ practical knowledge of teaching with practical work from the teachers’ perspective. In particular, inspired by the model of Magnusson et al. (1999), we revealed the contributions of various factors on five components of PCK, which made the research more systematic and in-depth. Moreover, we have tried to disclose the differences in the contributions of sources for teachers with different teaching experience. In this sense, we believe that this research contributed to existing knowledge base of practical work in the field of chemistry education.

As shown in the results, ‘teaching practice’ was the core source for all the five components of PCK. This finding was understandable. As we know, for the nature of PCK, it is a kind of practical knowledge, and its development is largely based on teachers’ personal teaching experience and self-reflection (van Driel et al., 2001). The finding also showed that in the pursuit of the development of their own PCK of teaching with practical work, chemistry teachers need to be diligent in reflection. Many researchers have reported the importance of teachers’ self-reflection on their teaching experience (e.g., Sung et al., 2009; Osmanoglu, 2016). This study provided new empirical data, which was basically consistent with the previous researchers’ suggestions. Besides, ‘curriculum materials’ was the core source for four components of PCK. In China, practical work is usually presented in the curriculum materials as teaching activities. Chemistry textbooks and accompanying teacher's guides describe in detail the objectives, procedures, and teaching strategies of each activity. By reading these materials, teachers can learn how to select, organize, and present practical work in practice. Moreover, we found that ‘classroom observations’ and ‘peer coaching’ were the other two core sources. For school administrators, the most valuable information revealed by this finding is that it may be very important and beneficial to promote classroom observation and daily exchange between teachers for the development of teachers’ PCK of teaching with practical work. From this point of view, school administrators should encourage chemistry teachers to observe more of the teaching of other colleagues and provide them with a working environment where they can easily communicate with each other (e.g., having all chemistry teachers work together in one or more offices). In other words, school administrators should help teachers build a community of professional development.

In contrast, ‘learning experience’ has been found to be the peripheral source for all the five components of PCK. This finding was basically consistent with Fan (2014)'s research, which did not support the assumption that existed in the field of teacher education: teachers teach the way they were taught (NCTM, 1991; Gardner, 1999). This result also showed that, in the view of teachers, learning experience as a student in the primary and secondary school has less impact than other sources on the development of their PCK of teaching with practical work.

Unfortunately, ‘in-service training experience’ was not highly rated by teachers and was even regarded as the peripheral source for the components of orientations toward practical work, and knowledge of laboratorial curriculum materials. As we know, the effective in-service training is very helpful to teachers’ professional development (Sneyers et al., 2016; Copriady et al., 2018). Hence, the finding in the present study was challenging for chemistry teacher educators. This means more quality in-service training on practical work is needed. For instance, in some continuing education program, seminars, or workshops, experts in the field of practical work and chemistry curriculum material designers should be invited to communicate with teachers on the purposes for teaching with practical work and the features of the laboratory teaching activities in curriculum. In addition, some representative cases of practical work in chemistry teaching (e.g., making galvanic cells; acid/base titration) can be selected in the training to discuss students’ difficulties, teaching strategies, and the methods of assessment, so as to help teachers enrich their practical knowledge of certain laboratory activities.

Furthermore, three sources were found to be significantly different among teachers who have different years of teaching experience: ‘pre-service training experience’, ‘classroom observations’, and ‘peer coaching’. Specifically, beginning teachers viewed their pre-service training experience more favorable for them to develop PCK than experienced teachers. This finding showed that in recent years, more and more attention had been paid to practical work in pre-service chemistry teacher training of normal universities in China, which was consistent with the idea of emphasizing the importance of practical work in the national chemistry curriculum standards (MoE, 2018) and the document of the Ministry of Education (MoE, 2019). Moreover, beginning teachers thought that their experience of classroom observations and peer coaching have more contributions for their development of some components of PCK than experienced teachers. In China, in the first few years of work for a beginning teacher, school administrators usually arrange for an experienced teacher as the master (called shifu in China) to guide and help the beginning teacher. In this way, a kind of ‘master-apprentice relationship’ has been formed (Feng, 2006). In the process of learning from experienced teachers, beginning teachers observe masters’ classroom teaching frequently and ask masters for advice on all aspects of teaching, which embodies the fact that PCK develops over time through experience, with particular expertise and individual idiosyncrasy. Therefore, it was not difficult to understand that beginning teachers thought they could obtain more knowledge about teaching with practical work from classroom observations and peer coaching. Based on this finding, we suggest that school administrators in other countries should follow the model of ‘master-apprentice relationship’ so as to provide the scaffold for the professional development of beginning chemistry teachers; at the same time, beginning teachers should also be willing to communicate and take the initiative to exchange ideas with colleagues, especially experienced teachers, to benefit from it.

Despite some theoretical and practical implications discussed above, there exist three limitations in this study. Firstly, the use of one tool ‘questionnaire’ for data collection limited the generalization of the findings. Secondly, this research relied on teachers’ evaluations of the relative contributions of each source. It is entirely possible that some of these sources contribute in ways that teachers cannot readily acknowledge or recognize. For example, it is likely impossible to accurately identify the many ways in which past learning experience has influenced one's current teaching practice. That is to say, while teachers’ metacognition can provide some meaningful information on the relative importance of these sources, it is not an absolute measure of the relative contributions of each source. Thirdly, as a quantitative research which focused on the current status, it was difficult for the present study to provide answers to the question about how different sources work together on the development of teachers’ PCK. Given that the environmental complexities experienced by teachers under different school cultures has a great impact on the development of their PCK, in the future, qualitative research should be conducted with chemistry teachers from the perspective of teacher learning and professional development (Simon and Cambell, 2012; Loughran, 2014) by observing and interviewing to explore the development of teachers’ PCK of teaching with practical work over time and along the teacher professional continuum. Such work will uncover the reasons behind teachers’ evaluations about these sources, and help chemistry teacher educators and school administrators better understand how to support teachers in developing their practical knowledge of teaching with practical work.

Conflicts of interest

There are no conflicts to declare.

Appendix

Question 2A

What do you think of your knowledge of laboratorial curriculum materials, referring to knowledge of the amount, arrangement, and features of the laboratory teaching activities in curriculum?

Question 2B

To what extent do the following sources have made to the development of your knowledge of laboratorial curriculum materials? Please select the number you approve of.

Sources	Very much	Somewhat	Little	Never
A. Learning experience	4	3	2	1
B. Pre-service training experience	4	3	2	1
C. In-service training experience	4	3	2	1
D. Classroom observations	4	3	2	1
E. Peer coaching	4	3	2	1
F. Professional journals	4	3	2	1
G. Online resources	4	3	2	1
H. Teaching practices	4	3	2	1
I. Curriculum materials	4	3	2	1

Question 4A

What do you think of your knowledge of instructional strategies for practical work, referring to knowledge of the specific procedures and strategies for carrying out instruction in laboratory?

Question 4B

To what extent do the following sources have made to the development of your knowledge of instructional strategies for practical work? Please select the number you approve of.

Sources	Very much	Somewhat	Little	Never
A. Learning experience	4	3	2	1
B. Pre-service training experience	4	3	2	1
C. In-service training experience	4	3	2	1
D. Classroom observations	4	3	2	1
E. Peer coaching	4	3	2	1
F. Professional journals	4	3	2	1
G. Online resources	4	3	2	1
H. Teaching practices	4	3	2	1
I. Curriculum materials	4	3	2	1

Acknowledgements

This research was sponsored by the Humanities and Social Sciences Research Program of the Ministry of Education of China, which is entitled the Transformation Mechanism of Science Curriculum Content Facing Society-Science Issues and Its Empirical Study (19YJA880045).

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Footnote

† In China, the education department of each administrative district set up a research department of teacher education, which will be equipped with 1–2 chemistry teaching supervisors whose regular work is to guide the teaching of teachers in the district, and regularly organize teaching and research activities to promote the professional development of teachers.

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