The Nature of Relationships Among the Components of Pedagogical

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The Nature of Relationships among the Components of PedagogicalContent Knowledge of Preservice Science Teachers: Ozone layer depletionas an exampleOsman N. Kaya a

a Firat University, Elazig, Turkey

To cite this Article Kaya, Osman N.(2009) 'The Nature of Relationships among the Components of Pedagogical ContentKnowledge of Preservice Science Teachers: 'Ozone layer depletion' as an example', International Journal of ScienceEducation, 31: 7, 961 — 988To link to this Article: DOI: 10.1080/09500690801911326URL:http://dx.doi.org/10.1080/09500690801911326

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International Journal of Science EducationVol. 31, No. 7, 1 May 2009, pp. 961–988

ISSN 0950-0693 (print)/ISSN 1464-5289 (online)/09/070961–28© 2009 Taylor & FrancisDOI: 10.1080/09500690801911326

RESEARCH REPORT

The Nature of Relationships among theComponents of Pedagogical ContentKnowledge of Preservice ScienceTeachers: ‘Ozone layer depletion’as an example

Osman N. Kaya * Firat University, Elazig, Turkey

Taylor and Francis Ltd TSED_A_291298.sgm10.1080/09500690801911326International Journal of Science Education0950-0693 (print)/1464-5289 (online)Research Report2008Taylor & Francis0000000002008Dr. [email protected]

The purpose of this study was to explore the relationships among the components of preservicescience teachers’ (PSTs) pedagogical content knowledge (PCK) involving the topic ‘ozone layerdepletion’. An open-ended survey was first administered to 216 PSTs in their final year at theFaculty of Education to determine their subject matter knowledge of ozone layer depletion. Then,the PSTs were classified as high-ability, average-ability, and low-ability groups according to theirscores on the survey. The interviews were carried out with 25 randomly selected PSTs from eachof these ability groups in order to determine their pedagogical knowledge and investigate the inter-relationships and intra-relationships among the components of the PSTs’ PCK for teaching thetopic ‘ozone layer depletion’. The results showed that there was a significant inter-relationshipbetween the subject matter and pedagogical knowledge of the PSTs. There were also significantintra-relationships among the components of the PSTs’ pedagogical knowledge, except for theknowledge of assessment. The results of statistical analyses (multivariate analyses of variance)revealed that there was a significant difference in the degree of the PSTs’ pedagogical knowledgeby the level of PSTs’ subject matter knowledge. These significant results were further supported by

evidence from qualitative analyses of the interview data. The implications drawn contribute to theimprovement of science teacher education.

Introduction

Pedagogical content knowledge (PCK), a special amalgam of content and pedagogi-cal knowledge that is unique and represents teachers’ special form of professional

* Department of Science Education, Firat University, Elazig, 23169, Turkey. Email: onafizk@

yahoo.com



962 O. N. Kaya

understanding, was first introduced by Shulman (1986, 1987). In Shulman’s view,PCK is the knowledge of how to transform subject matter so that it is comprehensi-ble to students, with the focus primarily on the teacher as a transformer of subjectmatter knowledge in teaching. Accordingly, PCK, which is connected with the

teaching of specific topics, may differ from subject matter knowledge. However,some scholars have argued that there is not always a sharp distinction between PCK and subject matter knowledge because subject matter knowledge functions as asource to be transformed for teaching (Tobin, Tippins, & Gallard, 1994). SinceShulman developed his idea of PCK, many science educators (e.g., Cochran,Deruiter & King, 1993; Lederman & Gess-Newsome, 1992) have discussed andrevised his model of PCK. For example, Cochran et al. (1993) revised Shulman’smodel of PCK as pedagogical content knowing by adding two other componentsbased on the constructivist view of teaching and learning. Lederman and Gess-Newsome (1992) used an analogy of the ideal gas law to demonstrate thatShulman’s model of PCK does not completely describe classroom teaching, just likethe behaviour of real gases is not explained by the law of the ideal gas. Van Driel,Verloop, and De Vos (1998) proposed another view of PCK, emphasizing morecraft or practical knowledge, meaning that PCK would be context dependent.Magnusson, Krajcik, and Borko (1999) also conceptualized a teacher’s knowledgefor the effective teaching of science as consisting of three forms of knowledge:subject matter, pedagogical knowledge, and contextual knowledge. In the PCK model of Magnusson et al. (1999), there are five components related to pedagogicalknowledge as follows: orientation toward science teaching, knowledge of the

curriculum, knowledge of science assessment, knowledge of science learners, andknowledge of instructional strategies.

As shown in the literature, there is no universally accepted view of what consti-tutes PCK. Many researchers have criticized and extended Shulman’s view of PCK by either including in PCK some of the knowledge categories (Van Driel et al.,1998), or by proposing different views of PCK (e.g., Cochran et al., 1993; Gross-man, 1990). In fact, Shulman’s initial description of teacher knowledge includedmany more categories (such as curriculum knowledge, knowledge of educationalcontexts, etc.) in his different publications (e.g., Shulman, 1986; Shulman & Gross-

man, 1988). A common view of PCK is that it is a combination of a teacher’spedagogy and understanding of content such that it influences the teaching in waysthat best engender students’ learning for understanding (Barnett & Hodson, 2001;Van Driel et al., 1998). With respect to science education, most science educatorsagree on the following components of PCK: subject matter knowledge and peda-gogical knowledge that consists of knowledge of students’ learning difficulties andconceptions, and instructional strategies (Van Driel et al., 1998). In addition tothese initial components of PCK, knowledge of curriculum and knowledge of assessment are also considered individual elements of PCK in this study becausehaving strong knowledge about the curriculum will enable science teachers tounderstand goals and objectives for students in the subject(s) that they are teaching,as well as the articulation of those guidelines across topics addressed during the



Relationships among the Components of PSTs’ PCK 963

school year (Magnusson et al., 1999; National Research Council [NRC], 1996). Interms of knowledge of assessment, most science teachers prefer to use traditionalassessment methods in many courses including laboratories (Abraham et al. 1997;Wiggins, 1996; Zoller, Ben-Chaim, & Kamm, 1997). However, the National

Science Education Standards document (NRC, 1996) specifically declared thateffective teachers of science must be knowledgeable about the various educationalpurposes for assessment, and it clearly emphasized that teachers should know howto implement and interpret a variety of authentic assessment approaches in theirscience classrooms and laboratories in order to improve students’ understanding of science. The purpose of this study was to investigate the inter-relationships andintra-relationships among the components of preservice science teachers’ (PSTs’)PCK involving the topic ‘ozone layer depletion’. Figure 1 represents the compo-nents of PSTs’ PCK investigated in this study, and the following research questionsformed the basis for this study.

● Is there a significant relationship between the subject matter and pedagogicalknowledge of the PSTs involving the topic ‘ozone layer depletion’?

● Are there significant intra-relationships among the components of the PSTs’pedagogical knowledge involving the topic ‘ozone layer depletion’?

● Are there significant differences in the degree of the PSTs’ pedagogical knowl-edge, including its components, by the level of PSTs’ subject matter knowledgeinvolving the topic ‘ozone layer depletion’?

Figure 1. C omponents of the PSTs’ PCK investigated

Literature Review

In the past two decades, there have been many studies (e.g., Lederman, Gess-Newsome, & Latz, 1994; Van Driel, De Jong, & Verloop, 2002) investigatingpreservice teachers’ PCK in science. The results of these studies showed thatmost PSTs had not only very superficial knowledge and various alternativeconceptions in science topics, but they also did not have adequate pedagogicalknowledge of the effective teaching of science. However, these results are notsurprising and should be expected because Magnusson et al. (1999), for example,

state that a teacher education programme could never completely address all thecomponents of PCK for PSTs. The studies of PSTs’ PCK also indicated that athorough and coherent understanding of subject matter acts as a prerequisite forthe development of PCK that is necessary for the effective teaching of science(Borko, 2004; Van Driel et al., 2002). For example, in a series of studies withPSTs, Van Driel et al. (2002) concluded that the development of preservice teach-ers’ PCK depends to a large extent on their subject matter knowledge becausePCK refers to the ability to transform subject matter knowledge in a manneraccessible to students.

In science education literature, very little is known about the ways PCK develops in PSTs (De Jong & Van Driel, 2004). However, a few scholars haverecently focused on investigating the nature and development of PSTs’ PCK after






an educational innovation was implemented in teacher education programmes inThe Netherlands (e.g., De Jong & Van Driel, 2004; De Jong, Van Driel, &Verloop, 2005; Van Driel et al., 2002). For example, Van Driel et al. (2002)specifically designed a teacher education course to investigate the development of

PCK within a group of 12 preservice chemistry teachers. They identified that thegrowth of PCK was influenced mostly by the preservice teachers’ teaching experi-ences, university-based workshops, and meetings with mentors. The results of thisstudy also showed that there were positive changes for most preservice teachers intheir knowledge of students’ learning difficulties and teaching activities and strate-gies although this development varied among students. They deduced that theobserved variations in the preservice teachers’ PCK were most probably becauseof differences in their subject matter knowledge. In another study, De Jong andVan Driel (2004) examined the development of eight preservice teachers’ PCK of the multiple meanings of chemistry topics; that is, the macroscopic, microscopic,and symbolic meaning. The preservice teachers were asked to choose and teach achemistry curriculum topic with a focus on the macro–micro–symbolic issue. Theresults of this study obtained from the individual interviews showed an increase inmost preservice teachers’ PCK. For example, preservice teachers not only elabo-rated but also added new teaching and students’ learning difficulties at the end of the study. In a recent study, De Jong et al. (2005) also investigated the changesof preservice teachers’ PCK in an experimental introductory course module. Theirmodule emphasized learning from teaching, rather than learning of teaching, byconnecting authentic teaching experiences with institutional workshops. Their

findings indicated that through learning from teaching, the preservice teachersfurther developed their PCK of using particle models. For example, all preserviceteachers demonstrated a deeper understanding of their students’ specific learningdifficulties. They concluded the module succeeded in contributing to the develop-ment of the preservice teachers’ PCK.

As a result of these studies, Van Driel and his colleagues reached two majorresearch findings related to the ways PCK develops in preservice teachers. First,certain components of the preservice teacher education programme such as class-room teaching experiences and feedback from mentors have strong effects on this

development. Second, there were noticeable relationships between the develop-ment of preservice teachers’ subject matter knowledge and their knowledge of students’ learning difficulties and instructional strategies. These kinds of relation-ships between subject matter knowledge and the components of the pedagogicalknowledge of science teachers were also reported by Halim and Meerah (2002).They found strong relationships between the subject matter and the components of pedagogical knowledge of 12 PSTs, such as the unawareness of students’ miscon-ceptions due to teachers’ lack of content knowledge of several physics concepts.These results indicated that one of the major obstacles to changing pedagogicalpractice in science classrooms was the poor knowledge of teachers in terms of thescience content that they were supposed to teach. As a result, Van Driel andcolleagues recommend addressing the subject matter knowledge explicitly as a



966 O. N. Kaya

basis for the development of preservice teachers’ PCK in science teacher educationprogrammes.

Significance of the Study

The significance of this study can be summarized under three headings. First, allprevious studies (e.g., De Jong & Van Driel, 2004; De Jong et al., 2005; Van Drielet al., 2002) opened a fruitful avenue of exploration of the complex relationshipsamong the components of preservice teachers’ PCK in science. However, in the fieldof science education, there has not been a study investigating these kinds of relation-ships with PSTs—especially from a quantitative perspective. Thus, there is a need tostudy the relationships among the components of PSTs’ PCK to be able to betterunderstand how PCK is developed in PSTs when they are becoming teachers of science. All of the previous studies were also carried out involving Shulman’s two keyelements of PCK, the knowledge of students’ learning difficulties and knowledge of instructional strategies, from only a qualitative perspective with a small number of preservice teachers. However, this study from both quantitative and qualitativeaspects particularly focuses on exploring the relationships among the components of the PSTs’ PCK involving an environmental science topic.

Second, the selection of the topic of ozone layer depletion could be seen animportant difference because the National Science Education Standards document(NRC, 1996) specifically declared that students in the middle school level startdeveloping awareness of the issues related to various natural phenomena, including

ozone layer depletion. The results of the studies (e.g., Boyes, Chamber, & Stains-street, 1995; Boyes & Stainsstreet, 1994; Dove, 1996) related to ozone layer deple-tion indicated that students at different educational levels had various alternativeconceptions that may result in an ill-informed citizenry with a reduced possibility of appropriate preventive actions by these citizens (Boyes et al., 1995). In this situa-tion, teachers can play an important role in teaching these concepts. With this inmind, an investigation of the relationships among the components of PSTs’ PCK inan environmental science topic becomes important as these PSTs will soon beteachers in schools preparing students to meet the general obligations that all

citizens face in our society.Third, this research was simultaneously conducted with one of the most compre-hensive science education reforms carried out in the past 60 years in Turkey(Turkish Ministry of National Education, 2005). The PSTs participated in thisstudy were the first teachers of science who graduated from the science teachereducation programmes to implement the new Science–Technology–Society (STS)-oriented curriculum in Turkey. The PSTs are expected to teach students majorenvironmental problems, including the ozone layer depletion, through contemporaryteaching approaches. Accordingly, understanding the relationships among thecomponents of the PSTs’ PCK involving an environmental science topic can help inconceptualizing how science teachers could be trained and develop their PCK betterin Turkey as an example for other developing countries.




Method

Sample

The subjects were 216 students (118 females and 98 males, aged 21–23 years) in

their final year (fourth year of their undergraduate degree) enrolled in scienceteacher education programmes at two universities in Turkey. They were seniors whocompleted their BA of Education degree three months later after this study. Seventy-five students (40 females and 35 males) were randomly selected from these 216students based on the level of their subject matter knowledge in order to explorepossible relationships among the PSTs’ PCK.

Science Teacher Education in Turkey

In Turkey, PSTs are placed in undergraduate teacher education programmesthrough a nationwide university entrance examination after graduating from highschools. Students must submit a list of programmes that they would like to study intheir order of preference after taking the examination. Students’ grade point aver-ages in high school are also important to be accepted by science teacher educationprogrammes. Most of the candidates for science teacher education programmescome from science programmes in Turkish high schools. These students take morescience courses and more advanced science courses at the high school level thanother students.

There are currently 37 universities that have middle school science teacherpreparation programmes in Turkey. Specifically, the middle school science teachereducation programme is a four-year programme (eight semesters) in all educationfaculties after the government established the Turkish Higher Educational Councilin 1981. The PSTs’ sole responsibility is to teach science to their students fromGrades 6 to 8 after graduating from the faculty. In this programme, the PSTsneeded to complete 154 credits of course work distributed in six areas: generalscience and laboratory courses; more specific science courses, such as analyticalchemistry; mathematics courses; general culture and language courses; generaleducation courses, such as Educational Psychology; and science methods courses(Turkish Higher Educational Council, 2006). Currently, most faculty membersteaching PSTs in the science teacher education programmes have backgroundsand research interests in science such as analytic chemistry and solid-state physicsrather than science education because science education is a very new academicfield in Turkish higher education. Many Turkish graduate students have beensupported by the Turkish Higher Educational Council and the Turkish Ministryof National Education for completing masters and PhD theses in science educa-tion in universities in the UK and the USA for the past 7–10 years. As in anyother developing country, because of the lack of financial resources and a huge

number of teacher candidates, ‘chalk and talk’ is the dominant teaching methodin the programmes.



968 O. N. Kaya

Data Collection

Subject matter knowledge of the PSTs. A five-item open-ended survey was used todetermine the PSTs’ conceptual understanding of ozone layer depletion. The surveywas developed based on the literature on preservice teachers’ understanding of ozone layer depletion (Boyes et al., 1995; Dove, 1996; Khalid, 2003). The literaturereview indicated that there were five main areas in which preservice teachers did nothave adequate conceptual understanding but rather held various alternative concep-tions related to the depletion of the ozone layer. The survey therefore focused onthese five main areas involving ozone layer depletion as follows: nature of the ozonelayer; causes of ozone layer depletion; consequences of ozone layer depletion; func-tions of ozone in the stratosphere; and relationships among ozone layer depletion,global warming and acid rain. To further substantiate the instrument’s validity, threespecialists (one each in the fields of environmental education, environmental

science, and survey construction) have examined the items on this survey. The alphareliability coefficient of the survey was 0.87. All survey questions are stated inAppendix A.

Pedagogical knowledge of the PSTs. A semi-structured individual interview was usedto determine the PSTs’ pedagogical knowledge on ozone layer depletion. Develop-ment of the interview questions was based on the review of the relevant literature(e.g., Magnusson et al., 1999) and negotiation with non-participant PSTs ( n = 30)in the previous academic year. The structure of the interviews was composed of four main sections that make up the pedagogical knowledge for teaching the topicof ozone layer depletion. Each section of interviews individually dealt with eachcomponent of the pedagogical knowledge. In choosing the PSTs for the interviewportion of the study, all 216 PSTs were first placed into one of three ability groupsbased on the level of their subject matter knowledge as determined by theirresponses to the open-ended survey. These groups briefly described below werecreated based on two important reasons: First, classification of these groups shouldallow making possible random selection of the 25 PSTs from each group in orderto avoid or minimize possible researcher bias and thus statistically better facilitate

the investigation of the relationships among the PSTs’ PCK. Second, the levels of subject matter knowledge of the PSTs in these three groups should be significantlydifferent from each other because one of the major goals of this study was to exam-ine whether or not the differences in the degree of the PSTs’ subject matter knowl-edge could be used to understand the differences in the degree of their pedagogicalknowledge involving the topic of ozone layer depletion. Different types of classifi-cations were also possible, but the grouping below is the most appropriate in termsof the nature and purpose of this research and the requirements of the statisticalanalyses.

● High-ability group: PSTs giving the appropriate answers to four or all of the fivequestions.




● Average-ability group: PSTs giving the appropriate answers to two or three of thefive questions.

● Low-ability group: PSTs giving the appropriate answer to only one of the fivequestions at most.

The semi-structured individual interviews were conducted with 75 randomlyselected PSTs (40 females, 35 males). There was no time limit for the interviews.Each interview conducted by the researcher lasted about 30–40 min. All interviewswere audio-recorded and transcribed verbatim. Some of the interview questions arepresented in Appendix B.

Data Analysis

PSTs’ responses to the open-ended survey and interview questions were assessed

based on the same three knowledge categories (appropriate, plausible, and naive)that were used by Vazquez-Alanso and Manassero-Mas (1999). A scoring outlinefor the three knowledge categories (3.5/1/0), suggested by Vazquez-Alanso andManassero-Mas (1999), was used to evaluate the PSTs’ responses to the surveyand interview questions. This gradual scoring rubric assesses respondents’ answersaccording to their proximity to the category scheme that judges have derived fromcurrent scientific knowledge of ozone layer depletion and current understandingin the reform documents (e.g., NRC, 1996) and the pertinent literature (e.g.,Gess-Newsome & Lederman, 1999) about the pedagogical knowledge that ascience teacher should have. These three knowledge categories are brieflydescribed below:

● Appropriate (3.5 points): PST’s response expresses an appropriate view.● Plausible (1 point): While not completely appropriate, PST’s response expresses

some plausible points.● Naive (0 point): PST’s response expresses a view that is inappropriate or not

plausible.

An example of the scoring rubric, criteria for the open-ended survey and interview

questions are given in Appendix C. Sample comments from three PSTs on thesecond question of the survey are included in Appendix D to illustrate differencesamong the three knowledge categories and how the scoring was done. The interviewtranscripts for all 75 PSTs were read and interpreted by the researcher. Cumulativescores of PSTs’ pedagogical knowledge were calculated using individual scores of allcomponents of their pedagogical knowledge. PSTs’ responses to the surveys andinterview questions such as ‘I do not know’ and ‘no response’ were assigned to thenaive category. One external expert cross-checked the analyses of the PSTs’ surveyand interview data with the original surveys and transcripts of the PSTs based on thescoring rubric and criteria. There were 95.30% and 94.70% agreements between theexpert and the researcher for the analyses of the PSTs’ survey and interview data,respectively.



970 O. N. Kaya

The inter-relationships and intra-relationships among the components of thePSTs’ PCK were investigated using the Pearson product-moment correlation coeffi-cient. To qualitatively identify the relationships between the subject matter andpedagogical knowledge of the PSTs, the transition of each PST in the three ability

groups of the subject matter knowledge level to the knowledge categories of appro-priate, plausible, and naïve in each component of their pedagogical knowledge weretracked. Multivariate analysis of variance (MANOVA) was conducted to explore theimpact of the level of PSTs’ subject matter knowledge on their pedagogical knowl-edge and its components. In this analysis, the level of PSTs’ subject matter knowl-edge was independent variable, and the levels of the PSTs’ pedagogical knowledgeand its components were dependent variables. SPSS 14.0 was used for tests of assumptions for MANOVA, analysis of variance, and inferential statistical analyses.

Results

The result section has been divided into the three following subsections: generalresults of the PSTs’ subject matter and pedagogical knowledge, inter-relationshipsand intra-relationships among the components of PSTs’ PCK, and differences inthe degree of PSTs’ pedagogical knowledge by the level of their subject matterknowledge.

PSTs’ Subject Matter and Pedagogical Knowledge

The results of all 216 PSTs’ responses to the open-ended survey of ozone layerdepletion are presented in Table 1 according to their understanding of each questionin the survey. The results showed that, on average, 101.40 (46.94%) PSTs hadnaïve, 52.80 (24.44%) PSTs had plausible and 61.80 (28.61%) PSTs had appropri-ate understanding about the topic of ozone layer depletion. Comparison of the mean( M = 6.23, SD = 5.70) of all 216 PSTs’ total scores with the maximum value of 17.50 of the survey indicated a success rate of 35.60%, which is low. However, thisresult is not surprising and is compatible with those of the previous studies onpreservice teachers’ understanding of ozone layer depletion (e.g., Boyes et al., 1995;

Dove, 1996; Khalid, 2003). With respect to the level of the PSTs’ subject matterknowledge, 126 (58.33%) PSTs were classified in the low-ability group because of giving only one appropriate answer in the survey at most. It was found that therewere 45 (20.83%) of the PSTs in the average-ability group because they were able togive an appropriate answer to two or three questions of the survey. Forty-five(20.83%) of the PSTs were classified in the high-ability group because of givingappropriate answers to four or all questions in the survey.

Compared with the results of other questions in the survey, the PSTs had a betterunderstanding of the nature of the ozone layer and consequences of ozone layerdepletion. For example, 97 (44.91%) PSTs were well informed about the location of the ozone layer in the atmosphere as well as the chemical structure and somephysical properties of ozone. In the third question, 95 (43.98%) PSTs had sound




understanding that the ozone layer protects human beings or other forms of life onEarth from harmful radiation, and more ultraviolet radiation that the ozone layerfilters out increases the incidence of skin cancer, eye problems and immunosuppres-sive diseases in humans and other animals. However, in the second question, only39 (18.06%) of the PSTs referred to the role of chlorines in chlorofluorocarbons(CFCs) splitting the chemical structure of ozone and could explain how chlorinefrom CFCs break down the ozone molecule into free oxygen. With respect to thefunctions of the ozone layer, 125 (51.87%) PSTs did not fully understand howozone works in the stratosphere; 135 (62.50%) PSTs also constructed incorrect rela-

tionships among ozone layer depletion, global warming and acid rain. For example,some PSTs had an alternative conception that depletion of the ozone layer is one of the main reasons for global warming because the increase of high-frequency radia-tion as a result of depletion of the ozone layer will produce more heat on the Earth.

All results in relation to the components of PSTs’ pedagogical knowledgeobtained from the interviews are presented in Table 2 based on the three knowledgecategories. The clear finding was that about one-half of the 75 PSTs had plausibleknowledge in all four components of the pedagogical knowledge, and only about25% of the PSTs had appropriate knowledge in the components of the pedagogical

knowledge, except for the knowledge of assessment. Regardless of the level of thePSTs’ subject matter knowledge, there were on average 14.50 (19.33%) PSTs inappropriate, 38.75 (51.67%) PSTs in plausible, and 21.75 (29.00%) PSTs in naïveknowledge categories with regard to their pedagogical knowledge involving the topicof ozone layer depletion. In general, the results of PSTs’ subject matter andpedagogical knowledge indicated that most PSTs did not have enough knowledge tobe able to teach the topic of ozone later depletion. However, this result should beconsidered reasonable for beginning teachers because of the following two reasons.First, many science teacher educators agree that the crucial factor in the develop-ment of PCK is teaching experience in authentic classrooms; however, the PSTs willadequately have this opportunity only after graduating from education faculties(Grossman, 1990; Lederman et al., 1994; Magnusson et al., 1999; Van Driel et al.,

Table 1. Number (percentage) of all 216 PSTs responding to the survey questions of ozone layerdepletion based on the knowledge categories

Knowledge category

Question Appropriate Plausible Naïve

Nature of the ozone layer 97 (44.91) 33 (15.28) 86 (39.81)Causes of ozone layer depletion 39 (18.06) 59 (27.31) 118 (54.63)Consequences of ozone layer depletion 95 (43.98) 78 (36.11) 43 (19.91)Functions of ozone in the stratosphere 50 (23.15) 41 (18.98) 125 (57.87)Relationships among ozone layer depletion,global warming and acid rains

28 (12.96) 53 (24.54) 135 (62.50)

Mean 61.80 (28.61) 52.80 (24.44) 101.40 (46.94)



972 O. N. Kaya

2002). Second, most science teacher education programmes do not integratecourses on subject matter, pedagogy, and field experiences in order to developpreservice teachers’ PCK as a whole (Van Driel et al., 2002).

The Inter-relationships and Intra-relationships among the Components of PSTs’ PCK

Pearson correlation coefficients among the components of the 75 selected PSTs’PCK are presented in Table 3. The results showed that there were significantpositive correlations between the PSTs’ subject matter and pedagogical knowl-edge, including all of its components. With respect to intra-relationships amongthe components of PSTs’ pedagogical knowledge, there were also significant posi-

tive correlations, except for the relationships between PSTs’ knowledge of assess-ment and other components of the pedagogical knowledge ( p > .05). Based onCohen’s (1988) interpretation of the strength of correlation coefficients into threelevels— r = 0.10–0.29 (small), r = 0.30–0.49 (moderate), and r = 0.50–1.0(large)—there were quite strong relationships between the PSTs’ subject matterand pedagogical knowledge ( r = 0.77, p < .0001), and the components of thepedagogical knowledge ( r = 0.63, 0.55, 0.60, p < .001), except for the knowledgeof assessment ( r = 0.33, p < .01), which is moderate. There were generally moder-ate intra-relationships among the components of the pedagogical knowledge,

except for the knowledge of assessment. For example, a significant correlation wasfound between PSTs’ knowledge of curriculum and knowledge of students’ learn-ing difficulties ( r = 0.49, p < .001) and instructional strategies and activities ( r =0.32, p < .01). There was also another significant correlation ( r = 0.48, p < .001)between the PSTs’ knowledge of students’ learning difficulties and instructionalstrategies and activities.

The significant relationships between PSTs’ subject matter and the componentsof the pedagogical knowledge as well as intra-relationships among the componentsof their pedagogical knowledge as revealed from the statistical analyses are alsoclearly shown in Table 4 and Figure 2 in terms of the qualitative perspective. Withrespect to the PSTs in the high-ability group of the subject matter knowledge level(see Table 4 and Figure 2), about 60% of the PSTs had appropriate knowledge of all

Table 2. Number (percentage) of the 75 PSTs with respect to the level of pedagogical knowledgebased on the knowledge categories

Pedagogical knowledge

Knowledgecategory

Knowledgeof

curriculum

Knowledge ofstudents’ learning

difficulties

Knowledge ofinstructional strategies

and activities

Knowledgeof

assessment Mean

Appropriate 18 (24.00) 17 (22.67) 19 (25.33) 4 (5.33) 14.50 (19.33)Plausible 39 (52.00) 38 (50.67) 36 (48.00) 42 (56.00) 38.75 (51.67)Naïve 18 (24.00) 20 (26.67) 20 (26.67) 29 (38.67) 21.75 (29.00)




components of their pedagogical knowledge, except for the knowledge of assessment(see Figure 2d). The tabulated data for the PSTs of the high-ability group showedthat there were on average 12.50 (50%) PSTs in appropriate, 8.25 (33.00%) PSTsin plausible, and only 4.25 (17.00%) PSTs in naïve knowledge categories in allcomponents of their pedagogical knowledge. Most PSTs in the high-ability groupcould distinguish the differences between the old and new curriculum with respectto not only the topic of ozone layer depletion but also the structure and generalobjectives of the curriculum. Most of them appropriately mentioned the status of thesubject and speculated about the balance between the environmental topics and theother science topics in the new STS-oriented science curriculum. Many PSTs gave

details about the possible learning barriers of students together with appropriatereasons indicating why students may have these difficulties or develop alternativeconceptions. Most of the teaching strategies and activities presented by the PSTs inthis ability group were the contemporary teaching approaches, emphasized in thereform documents (e.g., NRC, 1996) and the literature (e.g., Grandy & Duschl,

Table 3. Correlation coefcients among the components of PSTs’ PCK

Measures 1 2 2.1 2.2 2.3 2.4

1. Subject matter knowledge –

2. Pedagogical knowledge 0.77*** – 2.1. Knowledge of curriculum 0.63** 0.63** – 2.2. Knowledge of students’ learning difficulties 0.55** 0.76** 0.49** – 2.3. Knowledge of instructional strategies andactivities

0.60** 0.76** 0.32* 0.48** –

2.4. Knowledge of assessment 0.33* 0.42* 0.01 −0.01 0.17 –

* p < .01; ** p < .001; *** p < .0001.

Table 4. Relationships between the level of the PSTs’ subject matter knowledge and thecomponents of their pedagogical knowledge with respect to the knowledge categories

Level of subject matter knowledge

Components ofpedagogical knowledge High ( n = 25) Average ( n = 25) Low ( n = 25)

Knowledge of curriculum 16 A, 7 P, 2 N 2 A, 18 P, 5 N 14 P, 11 NKnowledge of students’learning difficulties

15 A, 4 P, 6 N 1 A, 20 P, 4 N 1 A, 14 P, 10 N

Knowledge of instructionalstrategies and activities

15 A, 7 P, 3 N 4 A, 16 P, 5 N 13 P, 12 N

Knowledge of assessment 4 A, 15 P, 6 N 15 P, 10 N 12 P, 13 NMean 12.5 A, 8.25 P, 4.25 N 1.75 A, 17.25 P, 6N 0.25 A, 13.25 P, 11.5N

A, P and N, knowledge categories of appropriate, plausible and naïve, respectively.



974 O. N. Kaya

2005; Yager, 2000), such as conceptual change strategies, inquiry-based learning,and problem-based learning. For example, in their teaching approaches they firstfocused on elaborating students’ learning difficulties and then incorporating theminto their teaching. With respect to the knowledge of assessment, more than one-half of the PSTs mentioned some authentic assessment approaches such as portfolio

assessment and concept mapping, but most of them did not successfully intertwinethe assessment with their teaching to improve students’ learning as revealed from thestatistical analysis. The following interview excerpts of one PST in the high-abilitygroup exemplify about these kinds of relationships among the PSTs’ subject matterand the components of the pedagogical knowledge as well as the intra-relationshipsamong the components of PSTs’ pedagogical knowledge. The codes A , P and N atthe end of each interview excerpt represent appropriate, plausible and naïve knowl-edge, respectively. All of the interviews were carried out in Turkish, the nativelanguage of all participants.

There was nothing about the topic of ozone layer depletion or other environmentalproblems. Fortunately, in the new curriculum, we have some aspects related to ozonelayer depletion because of the effects of the new STS approach to the curriculum.

Figure 2. Percentage distributions of the PSTs in the components of their pedagogicalknowledge with respect to the three ability groups of their subject matter knowledge level in thetopic ‘ozone layer depletion’




However, it is not enough to have environmentally literate citizens who keep theseproblems in mind because even new curricula do not have specific educational objec-tives emphasizing the ozone layer depletion. The environmental issues are used as frag-ments to make several science units such as matter and energy more related to the life of humans or other living creatures. (Knowledge of curriculum— A )

Students may have difficulties in understanding especially how ozone is depleted andprevents UV radiation from reaching the earth probably because of their age and levelof their chemistry knowledge. They may also have difficulties in linking the depletionof ozone layer to other environmental issues. For example, they may think that thedepletion of the ozone layer is one of the main reasons for global warming because thehole in the ozone layer allows a greater penetration of sunlight which results in raisingthe temperature of the earth. (Knowledge of students’ learning difficulties— A )

I start revealing my students’ prior ideas about the ozone layer depletion. How can youidentify their preconceptions? I ask them to draw what they know about the ozone layerdepletion on paper and explain their drawings in a small paragraph. Then, I ask themto form small groups of 3-4 and share their drawings with their peers in their groups.What do you expect to have after this activity? At least I will have a clear picture of whatmy students already know about the topic and so am ready to teach this topic. How do

you teach the topic then? For example, I can develop either several scenarios that arewritten as text or a 3-D model about the ozone layer depletion based on my observa-tions of my students’ preconceptions. Some parts of the scenarios or the model willcertainly have incorrect scientific information about ozone layer depletion. Studentswill be asked to evaluate the scenarios or the model and determine their scientificvalidity. At the end of a paragraph in which a question is posed, students are asked tostop reading. The evidence is presented that a misconception is incorrect, or a conceptis explained scientifically. Then, I ask them to discuss the statements in the text

among them and with me. During these discussions, I direct students along a paththat would lead them to correct conclusions. (Knowledge of instructional strategiesand activities— A )

I can ask them to draw what they learned about ozone layer depletion and explaintheir drawings in a small paragraph again. Then, the students may be also asked tocompare their pre and post-drawings and paragraphs as self-assessment. Looking atthe changes in students’ drawings and their own explanations will not only show mewhat they learned but also provide feedback to them about their own success in learn-ing about ozone layer depletion. (Knowledge of assessment— A )

Figure 2. Percentage distributions of the PSTs in the components of their pedagogical knowledge with respect to the three ability groups of their subject matter knowledge leve l in the topic ‘ozone layer depletion’

As shown in Table 4 and Figure 2, most PSTs in the average-ability group of thesubject matter knowledge level have plausible knowledge in all four components of their pedagogical knowledge. For the PSTs of this ability group, it was found that,on average, 1.75 (7%) PSTs have appropriate, 17.25 (69%) PSTs have plausible,and six (24%) PSTs have naïve knowledge in all components of their pedagogicalknowledge. In detail, many PSTs in the average-ability group had some knowledgeabout the new curriculum involving the topic ozone layer depletion and were able totalk about the general changes in the science curriculum. Most of them could iden-tify the possible learning difficulties of students but not with the appropriate reasonsof how or why students may have these learning difficulties or develop alternativeconceptions in the topic ozone layer depletion. The teaching approaches representedby most PSTs in this ability group were between traditional and contemporary



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teaching methods. Even though they believed teaching science should be student-centred rather than teacher-initiated, they could not appropriately portray theseideas in the relevant part of the interviews. Their approaches to assessment weregenerally traditional and did not allow them or students to monitor students’

progress in conceptual understanding, reflecting lower-order thinking skills. Inparticular, their purpose for assessment of 10 PSTs in this ability group was to testwhat their students learned rather than to improve the learning and teaching. Thefollowing interview excerpts of one PST in the average-ability group supportsthe claim that the subject matter and the components of pedagogical knowledge of the PSTs as well as the components of their pedagogical knowledge are stronglyrelated to each other.

Teachers can teach this topic within the new curriculum because it is developed basedon the STS perspective although there may not be a specific educational objective in the

curriculum related to this subject. (Knowledge of curriculum— P

)Some specific difficulties for students are the process of ozone layer depletion and therelationship between the ozone layer depletion and other environmental problems …Many middle school students may be used to thinking that there was a hole in ozonelayer in a physical meaning. (Knowledge of students’ learning difficulties— P )

I teach ozone layer depletion in five to six headings such as how it is depleted andwhat the consequences of ozone layer depletion are. I use several different deodorantsto show them the primary responsibility for the depletion of ozone layer goes tochlorofluorocarbon (CFC) gases. At this point, I ask questions such as do you thinkthese deodorants are harmful to the living creatures? If the ozone layer does not exist,what will be happen? As a result of their answers, I try to understand their priorunderstanding and then lead them to the more scientific conceptions. Can you explainmore how you lead them to the scientific conceptions? I use pictorial models representingthe scientifically accepted ideas related to each of my questions. (Knowledge of instructional strategies and activities— P )

At the end of each lesson, I will ask the students to keep a journal indicating what theylearned … At the end of my teaching, I also administer a survey that I develop based onthe students’ learning difficulties in the topic of ozone layer depletion. (Knowledge of assessment— P )

As seen in Table 4 and Figure 2, a certain type of the relationships between the

subject matter knowledge and the components of the pedagogical knowledge alsoexists for the PSTs in the low-ability group of the subject matter knowledge level. Itwas deduced from Table 4 that on average 11.50 (46%) PSTs had naïve, 13.25(53%) PSTs had plausible and only 0.25 (1%) PSTs had appropriate knowledge inall four components of the pedagogical knowledge. More than one-half of the PSTsin this group had superficial knowledge about the status of the subject in the newcurriculum, and the remaining PSTs had no knowledge about the curriculum withrespect to either any change in the curriculum or the status of the subject. In theknowledge of students’ learning difficulties, many PSTs, except for only one, hadeither plausible or naïve knowledge because they could not speculate the possiblelearning barriers of the students together with the logical reasons for these difficultiesin the topic of ozone layer depletion. The teaching approaches presented by many




PSTs in this ability group were close to the traditional teaching methods. Theybelieved teaching science primarily involves lecturing, explaining basic facts of ozonelayer depletion to the students. The primary underlying principle was that knowl-edge resides with the teacher and that it is the teacher’s responsibility to transfer that

factual knowledge to students. Much of their teaching approaches did not have astructure that presents many opportunities for students to contextualise science interms of their own experience and prior knowledge. With respect to the knowledgeof assessment, about one-half of the PSTs preferred to use traditional assessmentmethods, a single-occasion and timed exercise, after they taught the subject tostudents. The relationship between the PSTs’ subject matter and pedagogicalknowledge as well as the intra-relationships among the components of PSTs’ peda-gogical knowledge are portrayed in the following interview excerpts of one PST inthe low-ability group.

The curriculum has been recently changed based on the contemporary teachingapproaches. The old curriculum might not emphasize this subject. But I do not havedetailed information about what changed in it. (Knowledge of Curriculum— N )

Students may have more alternative conceptions or partial understanding about ozonelayer depletion than many other science topics. But, unfortunately, I have no opinionabout their possible learning difficulties related to this subject. (Knowledge of students’learning difficulties— N )

I can teach the subject based on some video records of TV programs, newspaper andmagazine articles and other visual materials. While students observe and read thesematerials, I first explain to them what the ozone layer is. Can you explain it more? I can

tell them, the ozone is a gas which occurs when three oxygen atoms are combined.Based on these materials, I can ask some students to answer certain critical questions inrelation to this topic …. If their responses to my questions are not enough, I can explainto them what the response should be in detail. At the end of the lesson, I summarizethe important points of the topic that students had difficulties in understanding.(Knowledge of instructional strategies and activities— N )

After teaching the topic, I will use a survey consisting of multiple choice and short-answer questions to determine what they learned. Following the exam, I explain thecorrect answer for each question to my students. (Knowledge of assessment— N)

Differences in the Degree of PSTs’ Pedagogical Knowledge by the Level of their Subject Matter Knowledge

The results of the 75 selected PSTs’ responses to the open-ended survey indicatedthat high-ability, average-ability, and low-ability groups had means and standarddeviations as follows: M high = 15.68 ( SD = 1.38), M ave = 7.76 ( SD = 1.15), and

M low = 1.34 ( SD = 1.28). The results of MANOVA, as shown in Table 5, indicatedthere was a statistically significant difference among the three ability groups on thedependent variables, consisting of the pedagogical knowledge and its components,simultaneously, F (10,136) = 11.49, p < .001; Wilks’ Lambda = 0.29; η 2 = 0.46.Based on Cohen’s (1988, pp. 283–288, see Table 8.2.2) interpretation of thestrength of partial eta squared values into three levels—0.01 (small effect), 0.06



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(moderate effect), and 0.14 (large effect)—this value ( η 2 = 0.46) indicated that themagnitude of significant difference among the three ability groups with respect tothe level of the PSTs’ pedagogical knowledge and its components was very large.

The results of analyses of variance presented in Table 5 indicated that there was a

statistically significant difference with respect to the PSTs’ pedagogical knowledge, F (2,72) = 56.94, p < .0001, and the components of the pedagogical knowledge, F KC (2,72) = 28.04, p < .001; F KSLD (2,72) = 15.08, p < .001; F KISA (2,72) = 18.90, p < .001; F KA (2,72) = 5.57, p < .01, among the three ability groups. As shown inTable 6, the results of post-hoc comparisons indicated that there was a significantincrease ( p < .001) in the mean scores of PSTs’ pedagogical knowledge from low-ability to average-ability groups, and from average-ability to high-ability groups. Withrespect to each component of the pedagogical knowledge, there was also a significantdifference ( p < .001) in favour of the PSTs in the high-ability group. However, thedifferences in mean scores were not statistically significant ( p > .05) in any componentof the pedagogical knowledge between average and low-ability groups.

Both quantitative and qualitative analyses of the interview data of the 75 PSTsregarding the level of their subject matter knowledge provide strong evidence for therelationships between the PSTs’ subject matter and pedagogical knowledge, includingall of its components, as well as among the components of their pedagogical knowledge,except for the knowledge of assessment. The qualitative results given in Figure 2 andTable 4 also show that there were, of course, some discrepancies between the surveyand interview data of the PSTs. For example, 24% of the PSTs in the high-abilitygroup of the subject matter knowledge level had naive knowledge in the following two

components of their pedagogical knowledge: the knowledge of students’ learning diffi-culties and assessment (see Figure 2b,d and Table 4). The MANOVA results alsoshowed that the level of the PSTs’ pedagogical knowledge significantly depends onthe level of their subject matter knowledge in the topic of ozone layer depletion.

Discussion

Since Shulman stated ‘the key to distinguishing the knowledge base of teaching liesat the intersection of content and pedagogy’ (1987, p. 15), teachers have been

Table 5. Results of multivariate and univariate analyses of variance for PSTs’ pedagogicalknowledge and its components with respect to the three ability groups of the PSTs

Analysis of variance

VariableMANOVA, F (10,136)

Pedagogicalknowledge,

F (2,72)

Knowledgeof

curriculum, F (2,72)

Knowledge ofstudents’ learning

difficulties, F (2,72)

Knowledge ofinstructionalstrategies and

activities, F (2,72)

Knowledgeof

assessment, F (2,72)

Group 11.49** 56.94*** 28.04** 15.08** 18.90** 5.57** p < .01; ** p < .001; *** p < .0001.




considered specialists at this intersection. Today there is a connection betweensubject matter and pedagogical knowledge in science teaching, either implicitly orexplicitly emphasized in many of the statements in the current science educationreform documents (e.g., NRC, 1996). Thus, if the aim is to improve science learn-ing, it must start with science teaching, requiring more research on this complexintersection among the components of the PSTs’ PCK because it will help us betterunderstand how PCK develops in the PSTs and what the nature of their PCK is.

The purpose of this study was to explore the nature of the PSTs’ PCK involving

the topic of ozone layer depletion. Accordingly, the results of this study contributeto the literature with respect to what are the kinds of relationships among thecomponents of their PCK, and, thus, how PSTs’ PCK can be developed better inscience teacher education programmes. In particular, science teacher educationreforms currently taking place in many developing countries, including Turkey,can benefit from the results of this study. These first showed that many TurkishPSTs, who are supposed to teach science based on the newly developed STS-oriented curriculum, are not capable of the primary purpose of universal scienceeducation—that is, to prepare students to act appropriately as citizens, which

includes participating in issues related to the environment. However, this result,showing the starting point of the PSTs’ PCK, should be considered reasonable ornormal because becoming a successful teacher takes many years in real classroomsettings.

The first research question of this study was to examine the relationship betweenthe subject matter and pedagogical knowledge of the PSTs involving the topic of ozone layer depletion. The statistical results indicated that the PSTs’ subject matterand pedagogical knowledge, including all of its components, are significantly relatedto each other ( p < .001). In other words, for the PSTs with strong subject matterknowledge, there was more appropriate pedagogical knowledge, whereas there wasmore naïve pedagogical knowledge for those with low subject matter knowledge.This statistically significant relationship was further supported by evidence from

Table 6. Descriptive statistics of the 25 PSTs in each ability group with post hoc comparisons forPSTs’ pedagogical knowledge and its components

High-abilitygroup (1)

Average-abilitygroup (2)

Low-abilitygroup (3)

Measure M SD M SD M SD Post hoc

Pedagogical knowledge 8.32 3.03 3.74 1.57 2.30 1.22 3 < 2 < 1Knowledge of curriculum 2.52 1.36 1.00 0.85 0.56 0.51 3, 2 < 1Knowledge of students’ learning

difficulties2.26 1.58 0.94 0.65 0.70 0.68 3, 2 < 1

Knowledge of instructionalstrategies and activities

2.38 1.43 1.20 1.09 0.52 0.51 3, 2 < 1

Knowledge of assessment 1.16 1.12 0.60 0.50 0.52 0.51 3, 2 < 1



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qualitative analysis of the interview data. For example, it was found that most of thePSTs with the less knowledge of the subject matter had very superficial knowledgeabout the newly developed STS-oriented curriculum that they are supposed tofollow in their own teaching probably within three–four months following the study.

On the other hand, PSTs who are more knowledgeable in subject matter have beenable to better know, discuss and adapt the curricular materials, guidelines andmandates to cover the interests, knowledge, and abilities of the students in order toincrease student understanding. In contrast to the PSTs with low knowledge in thesubject matter, the PSTs with sound understanding of the subject matter had abetter understanding of the knowledge of the students’ difficulties in learning thetopic of ozone layer depletion because they could present and speculate possibleconceptions that students have some challenges in understanding and alternativeconceptions that students already had before learning the topic or develop when theylearn the topic. With respect to the instructional strategies and activities, the PSTswho have more subject matter knowledge also have a better understanding of manypossible strategies that can be used to diagnose students’ preconceptions. They arealso aware that students’ preconceptions should be the starting point for instructionrather than starting with the textbook or lecture. Moreover, these PSTs are moreknowledgeable about how to ascertain and challenge learners’ ideas in productiveways and represent the subject matter in the interface between teaching andlearning. These results are consistent with the results of the previous studies withPSTs (e.g., De Jong & Van Driel, 2004; De Jong et al., 2005; Van Driel et al.,2002). These researchers reporting similar results from the qualitative perspective

found that the level of PSTs’ subject matter knowledge plays an important role inthe development of their PCK.

A significant correlation ( r = 0.33, p < .01) was also found between the subjectmatter knowledge and knowledge of assessment of the PSTs; however, this correla-tion was not as strong as other relationships. The reason for this inconsistent result isthat only four of the 75 PSTs had appropriate assessment knowledge. Regardless of the level of the PSTs’ subject matter, the assessment methods of most PSTs weretraditional rather than authentic. They thought that assessment and instruction areseparate entities rather than partners, and the purpose of the assessment was usually

giving students traditional tests to only inform them about their grade or rankingafter the instruction. This finding may be understood when the assessmentapproaches that the PSTs experienced in the education faculties in Turkey wereconsidered because most of the assessments of the PSTs’ conceptual understandingparticularly in science courses have been primarily done through traditional meth-ods, usually objective paper and pencil measures. This result about the PSTs’knowledge of assessment is compatible with the findings of Magnusson et al. (1999),who defined the knowledge of assessment as one of the components of scienceteachers’ PCK. They reported that research examining science teachers’ use of assessment showed that science teachers at all levels of schooling largely dependupon teacher-constructed objective tests to evaluate their students’ conceptualunderstanding.




The second research question of this study was to explore the intra-relationshipsamong the components of the PSTs’ pedagogical knowledge involving the topicozone layer depletion. The statistical analyses indicated that there were significantcorrelations among the components of the PSTs’ pedagogical knowledge. This means

that the PSTs who had more appropriate knowledge in one of the components of thepedagogical knowledge had a better understanding of other components of the peda-gogical knowledge. This finding, however, is not valid for the PSTs’ knowledge of assessment, which is not significantly related to the other components of their peda-gogical knowledge. Thus, the component of knowledge of assessment seems that itmay not be an appropriate element of the PSTs’ pedagogical knowledge. This contra-dictory result may be due to the way that the PSTs were educated from pre-schoolsto universities because of specific cultural factors (elementary-level, secondary-level,and university-level curricula, assessment system, textbooks, etc.). For instance, theselection of PSTs for teacher education programmes in Turkish universities is prima-rily based on the results of a central examination in which they have to answer 180multiple-choice questions in 195 min after high school. Moreover, although the PSTsin all Turkish universities have to complete 154 credits of course work distributedover six areas, there is only one course concerning the assessment strategies and tech-niques named measurement and assessment in the category of general education coursesas a three-credit hour. None of the courses in science teacher education programmesprovide the PSTs with another opportunity concerning assessment methods inscience. As a result, the Turkish PSTs do not have fruitful experience to learn andpractice their knowledge of assessment as a science teacher using science content. A

reasonable explanation for this situation is that the development of PSTs’ knowledgeand practice of assessment may be considered the last skill in PSTs’ PCK in mostscience teacher education programmes; alternatively, science teacher educatorsassume that this knowledge can be spontaneously and simultaneously developed inPSTs without specifically focusing on it during training. This explanation is alsosupported by the view of Magnusson et al. (1999) that science teachers’ knowledgeand practice in assessment methods is the most urgent need to be changed in all of thecomponents of teachers’ PCK over the next 10 years.

The last research question of this study was to investigate the effect of the level

of PSTs’ subject matter knowledge involving the topic of ozone layer depletion onthe degree of the PSTs’ pedagogical knowledge, including its components. TheMANOVA results supporting the correlational findings of this study also showed thatthe poor pedagogical knowledge of the PSTs could be explained equally well by thelack of their subject matter knowledge in the topic of ozone layer depletion. Theresults of qualitative analyses of the interview data are strong evidence for this signif-icant difference in favour of the PSTs in the high ability group. For example, mostPSTs in the high-ability group had either appropriate or plausible knowledge ratherthan naïve knowledge in terms of all components of the pedagogical knowledge, whilemost PSTs in the low-ability group had either plausible or naive knowledge ratherthan appropriate knowledge with respect to all components of the pedagogical knowl-edge. One of the possible reasons for this finding of this study may be the structure of



982 O. N. Kaya

Turkish science teacher education programmes because Turkish PSTs are learningmuch of their subject matter knowledge when taking science and laboratory coursesduring their first two years. They then take methods courses, which aim to promotethe PSTs’ pedagogical knowledge, in their last two years when they are becoming

teachers of science at education faculties in Turkey. Accordingly, this structure, withpedagogy and subject matter knowledge as separate entities in the programme, willimpede the PSTs, who gain low subject matter knowledge in the first two years, todevelop appropriate pedagogical knowledge in the last two years in the Turkisheducation faculties. In contrast, the PSTs with strong subject matter knowledge fromthe first two years may have more opportunities to integrate their content knowledgeinto their pedagogical knowledge that results in pedagogical content knowledge forscience education. Additionally, in all 61 courses that the PSTs have to take tobecome a science teacher, there are only three (5%) science methods courses in whichthey may develop their pedagogical knowledge for the effective teaching of science.

Overall, the major concern based on the results of this study may be what we asscience teacher educators need to do for the PSTs having inadequate PCK to be ableto teach science to students after graduating from science teacher educationprogrammes. Most teacher educators agree that there is an urgent need to have coursesintegrating all the components of PCK as a whole in science teacher educationprogrammes so that PSTs adequately develop their PCK before graduating from theprogrammes (e.g., De Jong & Van Driel, 2004; Lederman et al., 1994; Van Driel et al.,2002). However, in the Turkish middle school science teacher education programme,there is no such course focusing on combining subject matter, pedagogical knowledge,

and field experiences. Because the current programme is already very intensive, areasonable solution may be to include an additional year to the programme as a post-undergraduate teacher education programme. There should be only a single goal of this programme: to provide an opportunity for the PSTs to develop their PCK. Thiswill be a very fruitful opportunity especially for the PSTs who have low or averagelevels of PCK at the end of their undergraduate years. At the beginning of thisprogramme, teacher educators should first identify the pre-existing level of eachcomponent of PSTs’ PCK in specific science topics and pay attention to the PSTs’pedagogical content concerns. Therefore, the PSTs who are more aware of the level

of their PCK and teaching concerns explicitly will be easily motivated to develop theirPCK, and teacher trainers will be also more effective to help the PSTs (De Jong, 2000).This should be the beginning step in this programme because changing PCK, likescientific knowledge, will not occur through replication but through reconstruction.If PSTs try to develop their PCK, they must undergo a process of conceptual change.

Implications for Science Teacher Education

The results of this study allow us to begin to ask important questions of the model of PCK as related to science teacher education, such as ‘How do the relationshipsamong the components of the model of PCK help us think differently about scienceteacher education?’ and ‘How can we as science teacher educators help the PSTs,




who have low and average subject matter knowledge, to improve their pedagogicalknowledge for the effective teaching of science?’ First, the results of this study implythat the current structure of the programme—that pedagogy and subject matterknowledge are separate entities—should be changed. For example, while waiting for

the third year at the education faculties, the PSTs may simultaneously take theircourses of subject matter and pedagogical knowledge beginning from the first yearsin the programmes so that there are more opportunities for the PSTs, who came tothe programme with low science background from the high school or gain lowknowledge in science in the programme, to develop appropriate pedagogical knowl-edge in the following years.

Second, science teacher education programmes should also have specific coursesrelated to all components of pedagogical knowledge. For example, besides the currentmethods courses, other courses should be added to the programme related to thefollowing: the structure, general aims, and content of the current curriculum; students’learning difficulties in science topics; teaching strategy and activities for specific sciencetopics; and assessment approaches in science. Even if the recommended changes aboveare accomplished, it may not be thought enough to sufficiently develop PSTs’ PCK within the current undergraduate programme, or these changes may be consideredunfeasible or unrealistic for the current programme, consisting of 154 credits of coursework ( n = 61). Accordingly, another way to efficiently develop PSTs’ PCK is an addi-tional year on a post-undergraduate teacher education programme. The sole goal of this programme would be to develop PSTs’ PCK for the effective teaching of science.Furthermore, in this programme, the knowledge of assessment can be examined as

an individual part of PSTs’ PCK through their experiences with authentic assessmentapproaches such as portfolios and concept mapping.

The major limitation of this study was that the PSTs’ practical or craft knowledgeinvolving ozone layer depletion could not be investigated because the PSTs did nothave a long enough practicum period, and most of the school administrators andmany inservice science teachers with whom the PSTs are doing their practicum asstudent-teachers are anxious and reluctant to let the PSTs teach the topic of ozonelayer depletion due to the newly developed and practiced STS-oriented sciencecurriculum. Accordingly, future research should focus on questions related to the

triadic relationships among the subject matter, the pedagogical and practicalknowledge of the PSTs and especially the way they transform their subject matterknowledge into the real classroom settings. In particular, future research should alsoinvestigate the difference of how PSTs having different levels of PCK, such as highsubject matter/high pedagogical knowledge versus high subject matter/low pedagogi-cal knowledge, are teaching science topics to students in real classrooms.

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Appendix A. Survey questions

1. What is the ozone layer? Please also explain the chemical structure and physicalproperties of ozone.

2. What is the main cause of ozone depletion? Explain how it depletes the ozonelayer.

3. What are the effects of ozone depletion on human beings or other forms of lifeon the planet? Explain your answer with reasons.

4. Explain how the ozone works in the atmosphere?5. What do you think are the relationships among ozone layer depletion, global

warming and acid rain? Explain your answer with reasons.

Appendix B. Some interview questions in each component of thepedagogical knowledge

The knowledge of curriculum

● What do you know about the place of ozone layer depletion in the middle schoolcurriculum?

● Is there any specific educational objective in the curriculum related to thissubject?

The knowledge of students’ learning difficulties ● Do you know the possible learning difficulties (e.g., alternative conceptions or

partial understanding) of students on the concepts related to ozone layer depletion?● Can you explain how students may or develop these difficulties in learning the

concepts related to ozone layer depletion?

The knowledge of instructional strategies and activities

● What kinds of teaching approaches do you think to use for teaching the conceptsof ozone layer depletion to the middle school students?

● What would you do in your teaching to help students gain a better understandingof the concepts of ozone layer depletion?

The knowledge of assessment

● What kinds of assessment approaches do you think to use to evaluate students’understanding of the concepts of ozone layer depletion?

● Could you explain how you assess students’ learning of the concepts of ozonelayer depletion?




Appendix C. Examples of the scoring rubric, criteria for the survey andinterview questions

Appropriate (3.5 points) Plausible (1 point) Naïve (0 point)

Causes ofozone layerdepletion

(1) Referring the CFCs as themain cause of ozone layerdepletion.(2) Explaining how chlorinefrom CFCs breaks down ozonemolecule into free oxygen.

(1) Referring the CFCsas the main cause ofozone layer depletion.

(1) Referring othersources such as caremissions and toxicgases for the main causeof ozone layer depletionrather than CFCs.

Knowledgeof students’

learningdifficulties

(1) Giving details aboutstudents’ difficulties in

understanding the subject,including alternativeconceptions and partialunderstandings.(2) Explaining how and whystudents may have theselearning difficulties or developalternative conceptions.

(1) Giving detailsabout students’

difficulties inunderstanding thesubject, includingalternative conceptionsand partialunderstandings.

(1) Not describing anystudents’ difficulty in

understanding thesubject.



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Appendix D. Sample comments from three PSTs on the second question ofthe survey

PST-17: Ozone is a molecule composing of three oxygen atoms. Depletion of ozone

means splitting the chemical structure of ozone, leading to the decrease of its concen-tration. Destruction involves chemical reactions. This occurs because of humanrather than natural input. I mean we introduce chemicals into the atmosphere thatcause the ozone to be destroyed because these chemicals were either used as solvents,propellants, or refrigerants. The major chemical is chlorofluorocarbons (CFCs). I cansummarize this chemical process as follows: First, the CFCs in the stratosphere arebombarded with UV radiation from the sun. This causes the CFC molecule to releasea chlorine atom which is free to interact with other atoms. Then, the free chlorineatom can collide with an ozone molecule. The chlorine atom strips an oxygen atomfrom the ozone molecule, leading to the formation of two new molecules, O

2 and

ClO. Each chlorine atom will probably destroy over a thousand ozone moleculesbecause the chlorine monoxide can interact with a free oxygen atom, resulting in theformation of oxygen molecule and a free chlorine atom again. This chlorine atom isnow free to react with more ozone molecules. (Appropriate idea)PST-78: The depletion of the ozone layer means decreasing the number of ozonemolecules in the stratosphere. Unfortunately, they are being catalyzed by chemicals.The major threat is chlorofluorocarbons (CFCs). This chemical is used in industrysuch as solvents and in our refrigerator or freezer. The amount of the CFCs deter-mines the degree of ozone depletion, making the ozone layer thinner than before.

(Plausible idea)PST-197 : The hole in the ozone is getting bigger because of human impact onnature. Our environment is becoming worse compared to a hundred years agobecause today there are many more factories and other facilities in our lives such asour cars. CO and CO 2 from car emissions and all atmospheric pollution especiallycoming from factories are responsible for ozone layer depletion. (Naïve idea)

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The Nature of Relationships Among the Components of Pedagogical