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Teaching and Teacher Education 25 (2009) 259–267

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Teaching and Teacher Education

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Teachers’ views on understanding evolutionary theory: A PCK-study in theframework of the ERTE-model

Esther M. van DijkDidaktisches Zentrum, Carl von Ossietzky University Oldenburg, D-26111 Oldenburg, Germany

a r t i c l e i n f o

Article history:Received 14 December 2007Received in revised form 28 August 2008Accepted 18 September 2008

Keywords:Pedagogical Content KnowledgeTeacher educationPre-scientific conceptionsTheory of evolutionNature of science

E-mail address: e.van.dijk@uni-oldenburg.de

0742-051X/$ – see front matter � 2008 Elsevier Ltd.doi:10.1016/j.tate.2008.09.008

a b s t r a c t

The study of Pedagogical Content Knowledge (PCK) that is presented in this paper aims to obtain animpression of teachers’ knowledge and beliefs concerning teaching evolutionary theory. The startingpoint of this project was the development of the Educational Reconstruction for Teacher Educationmodel (ERTE). The PCK-study shows that teachers’ attitudes toward students’ conceptions of evolu-tionary theory are not always constructive and that teachers often lack awareness of the historical natureof biology. Scenario questions proved to be effective interview items in order to acquire a detailed pictureof teachers’ ways to react to students’ pre-scientific conceptions.

� 2008 Elsevier Ltd. All rights reserved.

1. Introduction

Evolutionary theory is central to biology and a thoroughunderstanding of evolution is a prerequisite for participating inalmost any debate regarding biological themes. But the theory ofevolution is also a complex theory about which a great variety ofconceptions exist among the general public. Secondary schoolteaching aims to guide the development of the students’ pre-scientific conceptions toward the scientific viewpoint. The experi-ence-based ideas about evolution with which students enter theteaching process form the bases for this developmental process.However, research has shown that students often leave the learningprocess without having acquired a scientifically valid conceptualframework of evolutionary theory (Alters & Nelson, 2002).

That knowledge of the students’ topic specific pre-scientificconceptions is important for science teaching is widely recognizedin the field of educational research and much research has alreadybeen undertaken to uncover and describe these pre-scientificconceptions. Additionally, it is also important for science teachingto study the knowledge and beliefs that teachers have. Van Driel,Verloop, and De Vos (1998) observed that there is a lack of studieson science teachers’ topic specific Pedagogical Content Knowledge(PCK). Furthermore, they suggested that such PCK studies couldbenefit from incorporating research on student learning. Theliterature on students’ conceptions concerning evolutionary theory

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should therefore be complemented by studies on the same topicfrom the teachers’ perspective.

The PCK-study that is presented in this paper is based on theassumption that experienced teachers have developed their PCKwith respect to the topic of evolutionary theory in their teachingpractice and that this knowledge is worth exploring. The aim of thisstudy is to obtain an impression of teachers’ knowledge and beliefs1

concerning the teaching of evolutionary theory. The starting pointof the project was the development of a research model for thestudy of PCK, the Educational Reconstruction for Teacher Educationmodel (ERTE), which was published in a previous issue of Teachingand Teacher Education (Van Dijk & Kattmann, 2007). This previouspaper also includes a discussion of the history, the nature and thesources of the concept of PCK. The study of teachers’ PCK onevolutionary theory, which is presented in this second paper, is thefirst empirical study in the framework of the ERTE-model. Thisqualitative study can be seen as a first step toward the developmentof a mixed method approach to the study of PCK. The ERTE-model isbased on an established research model, the model of EducationalReconstruction (ER). This ER-model was developed for the design oflearning environments based on a critical analysis of the subjectmatter in relation to an empirical study of students’ pre-scientificconceptions (Duit, Gropengießer, & Kattmann, 2005). A shortdescription of the ERTE-model will be presented in Section 3.

1 I use the phrase ‘‘knowledge and belief’’ because it is difficult to makea distinction between knowledge – defined as justified beliefs– and beliefs (see alsoFenstermacher, 1993).

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The PCK-study provides an overview of the teachers’ knowledgeof students’ problems with understanding evolutionary theory andprovides information on teachers’ attitudes toward students’ pre-scientific conceptions. The PCK-study shows that teachers’ attitudestoward students’ conceptions of evolutionary theory are not alwaysconstructive, that is they do not always help teachers to addressstudents’ learning problems adequately. The study further showsthat teachers display a variety of conceptions concerning the natureof science (NOS) and that teachers often lack awareness of thehistorical nature of biology. The evaluation of the PCK-studysuggests that scenario questions are the most effective interviewitems in order to acquire a detailed picture of teachers’ ways to reactto students’ problems concerning evolutionary theory. In Section 4the methodology of the study is described. In Section 5 the findingsof the PCK-study are presented followed by a presentation of theconclusions and an outlook in Section 6. But first a short descriptionof the nature and sources of PCK is presented in Section 2.

2. Pedagogical Content Knowledge

There is no universally accepted conceptualization of whatexactly PCK is. Shulman introduced PCK as a concept that represents:

[T]he blending of content and pedagogy into an understandingof how particular topics, problems, or issues are organized,represented, and adapted to the diverse interests and abilities oflearners, and presented for instruction (Shulman, 1987, p. 8).

PCK concerns the teaching of specific topics, and is therefore to bediscerned from general knowledge of pedagogy and subject matterknowledge. The ‘PCK’ concept is a tool for studying certain aspects ofteacher knowledge. PCK refers to a teachers’ personal and privateknowledge, but PCK cannot be seen to be a real separate knowledgedomain in the human mind. Rather, it is a heuristic device forthinking about teacher knowledge (Borko & Putnam, 1996).

All scholars seem to agree with Shulman (1987) that theunderstanding of students’ specific learning difficulties and theknowledge of subject matter representations to overcome thesedifficulties are two essential elements of PCK (Van Driel et al., 1998).The phrase ‘subject matter representation’ does not only refer totextbook examples. It also refers to analogies and metaphors thatteachers use to clarify difficult points. As this study will show,teachers often react to students’ problems concerning adaptationby using briefly formulated analogies to illustrate where, accordingto the teacher, the students are going wrong. The two relatedelements of PCK, knowledge of students’ pre-scientific conceptionsand subject matter representations, enable teachers to anticipatestudents’ problems with respect to a specific topic and to react inappropriate ways. Additionally, teachers have to be able to handlethe complexities of their daily teaching practice flexibly: They haveto be able to analyse the value of different textbook examples inrelation to a specific topic and they have to be able to follow thevarious ideas that students express. This requires teachers not onlyto have adequate knowledge of the subject matter, they also have tobe able to use this subject matter knowledge in their teaching (Ball& Bass, 2000). Therefore, a third element of PCK is distinguished:This element of PCK, which is simply called ‘subject matterknowledge for teaching’, enables the teacher to react adequately indifferent and unanticipated situations.2

2 ‘Subject matter knowledge for teaching’ is comparable with what Ball and Bass(2000, p. 89) describe as ‘pedagogical useful mathematical understanding’. Themain difference with the conceptualization of teacher knowledge presented here isthat according to the view of Ball and Bass (2000) this knowledge is not included inPCK. However, I suggest that ‘subject matter knowledge for teaching’ consists ofa blending of content and pedagogy and should therefore be included in PCK.

A review of the literature on science teachers’ PCK shows that,although the amount of research is limited, the results of theexisting studies are consistent: ‘‘Although teachers have someknowledge about students’ difficulties, they commonly lackimportant knowledge necessary to help students overcome thosedifficulties’’ (Magnusson, Krajcik, & Borko, 1999, p. 106). Studies ofteachers’ PCK indicate further that subject matter knowledge isa prerequisite for the development of PCK and that PCK develops inthe actual teaching practice of teachers (Grossman, 1990; Van Drielet al., 1998). Additionally, these studies indicate that specific cour-ses or workshops have the potential to influence the developmentof PCK.

3. The model of educational reconstruction for teachereducation

The main purpose of the study described in this paper is toformulate recommendations for teacher education with respect tothe teaching of evolution. Teacher training is necessary for noviceand experienced teachers to develop their PCK in their teachingpractice; it enables the teachers to learn from their experiences(Grossman, 1990; Van Driel et al., 1998).

The study of teachers’ PCK on evolutionary theory aims toanswer the following three research questions (RQ):

(RQ1) What ‘subject matter knowledge for teaching’ do biologyteachers have concerning the topic of evolutionary theory?

(RQ2) What knowledge and beliefs do biology teachers have ofstudents’ pre-scientific conceptions with respect to evolu-tionary theory?

(RQ3) What knowledge and beliefs do biology teachers have ofsubject matter representations regarding the theory ofevolution?

The ERTE-model provides the framework for an integrativeapproach of the study of teachers’ PCK. The ERTE-model aims tomake explicit how the different elements influence each othermutually (Fig. 1). For example, the empirical PCK-study providesknowledge on students’ difficulties with understanding adaptationand the misconceptions literature influences the development ofthe interview protocol for the PCK-study. The model can be used toexplore teachers’ knowledge and beliefs about (1) the ‘subjectmatter for teaching’, (2) students’ pre-scientific conceptions, and(3) representations of the subject matter, in relation to theempirical literature on (a) learning environments, (b) students’

Fig. 1. The model of educational reconstruction for teacher education.

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pre-scientific conceptions and in relation to (c) an analysis ofevolutionary theory. In Section 5 of this paper the results of thePCK-study on evolutionary theory are thus discussed in relation tothe available research literature on students’ conceptions, subjectmatter representations and evolutionary theory.

The ERTE-model was developed by Van Dijk and Kattmann(2007) with the aim to improve teacher education. An importantassumption that underlies the ERTE-model is that the content forteacher education needs to be ‘educationally reconstructed’. Twoelements form the basis for the development of teacher education.The first element is the empirical study of teachers’ PCK: Teachersdevelop PCK in their individual teaching practice and researcherstry to construct new educational ideas from the PCK of experiencedteachers or observe problems that teachers have with certaintopics. These experience-based educational ideas and problems, inturn, are used to develop elements of teacher education. A secondelement of this developmental process is the empirical knowledgethat has been gathered concerning students’ pre-scientificconceptions, subject matter and subject matter representations.This empirical knowledge has to be reconstructed for teachereducation if it is to be taught to teachers in training in an integratedmanner.

4. On method

4.1. Method & participants

The study described here constitutes a first exploratory PCK-study on evolutionary theory in the framework of the ERTE-model.The research project consisted of nine one-on-one interviews, eachof approximately one-hour duration. Interviewing was found to bethe most suitable method for this PCK-study because duringobservations only a part of a teacher’s PCK can be seen; it istherefore important that the teachers themselves articulate theirPCK (Kagan, 1990). The exploratory nature of the study madea strong standardization of the interview unwanted. The set-up ofthe interview needs to leave room for the interviewer to ask clar-ifying questions.

The nine biology teachers from the state of Lower Saxony inGermany chose to participate on a voluntary basis. All of theparticipating gymnasium3 teachers have an academic backgroundin biology. Since teaching experience appears to be an importantfactor for the development of PCK, all participants had more than 5years of teaching experience in biology: The number of years ofteaching experience ranged from 6 to 34 years. All but one of theteachers are qualified to teach chemistry besides biology. Allinterviewees held the position of a so-called ‘Fachleiter’, meaningthat they were responsible for the training of beginning teachers. Itwas expected that this would have a positive effect on their abilityto articulate their PCK. Although these teachers are recognized tobe experienced, they cannot be considered teaching experts, ascriteria for selecting teaching experts are difficult to define anduse.4

4.2. Developing the interview protocol

A review of the available interview protocols for PCK studies wasmade to get an overview of the interview questions that were

3 In Germany three types of secondary education exist. The gymnasium providesthe highest level of secondary education in Germany and prepares the students(aged 11–19 years old) for university.

4 It must be noted here that the normative problem concerning the lack ofcriteria for experts reappears in the discussion section. The discussion is necessarilybased on conceptions concerning good or successful teaching and these concep-tions must become explicit within the argumentation.

formulated for other studies of teachers’ knowledge and beliefs. Forexample, Loughran, Mulhall, and Berry (2004) described theirstruggle to find a method for accessing teachers’ PCK. They devel-oped a table in which the ‘big ideas’ of the particular subject areaform the columns. The rows were filled in by the researchers andparticipating teachers with important aspects to take into accountwhen teaching a particular content area. Gudmundsdottir,Reinertsen, and Nordtømme (2000) used Klafki’s Didaktik analysismodel to study certain aspects of PCK. Klafki’s model comprises fivequestions that a teacher should ask in the preparation of instructionconcerning: (1) the contemporary meaning of the content for thestudents, (2) the future meaning of the content for the students, (3)the content structure, (4) the exemplary value of the content and(5) the pedagogical representations of the ideas.

The review of available protocols formed the basis for thedevelopment of the interview protocol used in the PCK-study thatis presented here: The collected questions were related to the threemain research questions, which resulted in the formulation of fiveopen sub-questions that form the core of the interview protocol(see Appendix, questions 1–5, part 2 and 3). The first sub-questionconcerning the teachers’ views on the core ideas within theirteaching of evolution determined the topics that were discussed inpart 3 of the interview. This question not only provided insight intothe teachers’ PCK, the question also helped the interviewer tostructure the interview based on the core ideas mentioned by theinterviewee.

Scenario questions, as used by Kennedy, Ball, and MacDiarmid(1993), were included to explore the teachers’ PCK further (seeAppendix, part 4). Kennedy et al. (1993, p. 11) developed an inter-view in which the teachers are confronted with hypotheticalscenarios that are meant to generate situations ‘‘in which theteacher would need to take into account both subject matter andlearners’’. The scenario questions are based on two open questionstaken from the Evolution Concept Test from Bishop and Anderson(1990) and two multiple choice questions (16 and 18) taken fromthe Conceptual Inventory of Natural Selection developed byAnderson, Fischer, and Norman (2002) concerning micro-evolutionary processes. Two additional open scenario questionsconcerning common descent were included. In the misconceptionsliterature the focus often lies on micro-evolutionary processes, butto avoid this bias, questions on evolution as the history of life wereincluded. Questions concerning the teacher’s background – expe-rience and education – form an additional part of the interviewprotocol (see Appendix, part 1).

4.3. Data analysis

For the PCK-study nine interviews were conducted and recor-ded. The recordings of the interviews were analyzed with theQualitative Content Analysis (QCA) method (Mayring, 2003). QCA isa rule-based analysis procedure: The text is analyzed step-by-step,following fixed rules of analysis. This procedure safeguards thequality of the study by providing a clear documentation of theindividual steps that were taken, thus allowing other researchers tofollow the analysis every step of the way and increasing the reli-ability and internal validity of the study. A detailed description ofthe interview contexts increases the external validity of the study.With regard to these quality criteria it should be noted that notionslike reliability and validity are commonly associated with quanti-tative methods, while the applicability of these notions to quali-tative research is subject of debate. However, in qualitative researchpractice reliability and validity are widely used as quality criteria(see, for example, Graneheim & Lundman, 2004; Spencer, Ritchie,Lewis, & Dilton, 2003). Moreover, several authors have argued thatthe same concerns about the quality of research are at stake in bothqualitative and quantitative studies and that therefore reliability

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and validity are equally appropriate quality criteria in both researchdomains (e.g. LeCompte & Goetz, 1982; Mason, 2002).

QCA is based on the premise that the data from the interviewscan be reduced to categories. Depending on the research questionthe formation of categories is a more inductive or more deductiveprocedure. In case of RQ1 a more inductive category definitionapproach was used: the categories were deduced without referenceto theoretical categories that are formulated beforehand. In case ofRQ2 and RQ3 a more deductive approach was used: theoreticalconsiderations led to the formation of provisional categories. Theseprovisional categories were based on the theoretical background ofthe study, in this case evolutionary theory and misconceptionsthereof. The analysis consisted in the assignment of the category toa passage of text. A problem with the use of QCA in the case of broadresearch questions like RQ2 and RQ3 is that the use of categoriescan be restrictive. However, the fact that already much researchwas done on students’ pre-scientific conceptions and problemsconcerning evolutionary theory makes the use of categories in thisPCK-study less restrictive.

The data analysis procedure consisted of four steps: (1) Theinterviews were transcribed and analyzed. (2) The passages of theinterview text related to the three main research questions werechosen from the recording of the interview. These passages werethen edited: the text was summarized and non-meaningful state-ments were taken out. (3) Different text passages concerning thesame issue were categorized (in the case of RQ2 and RQ3 accordingto the provisional categories) and integrated. These text passageswere then edited; the statements were rephrased in wholesentences, grammatically corrected and summarized. Similarstatements were summarized in one statement. The words used bythe interviewees, especially metaphors and analogies, wereretained. (4) In the fourth step the categories within the differentinterviews that concern similar issues were brought together inorder to get a picture of the main categories within this PCK-study.The results of the analysis are discussed in the next section.

5. Findings

5.1. RQ1: ‘subject matter knowledge for teaching’

RQ1 concerns the ‘subject matter knowledge for teaching’ thatteachers have. The results of RQ1 are discussed in relation to theliterature on evolutionary theory and pre-scientific conceptions ofevolution, as is explicated in the ERTE-model (Fig. 1).

The teachers were asked what they thought the status ofevolutionary theory is within biology education. The intervieweesreferred foremost to evolution as a central theme within biologyeducation. They described the status of the theory of evolution interms of: ‘the central theme’, ‘the basis’, ‘the only theory’, ‘related toall’, ‘ultimate causation’ or ‘the answer to a Why-question’. Theteachers were then asked what the key concepts within theirteaching of evolutionary theory are. In reaction to this question theinterviewees referred foremost to concepts concerning theprocesses of evolution: ‘mutation’ and ‘selection’. The teachersfurther mentioned a comparison of the different theories or theirdevelopmental history; variation; causes of variation; recombina-tion; overproduction; time; evidence; homologies; speciation; andthe tree of life.

These results confirm the observation that biology teachingfocuses foremost on micro-evolutionary processes (Catley, 2006;Kattmann, 1995). The term ‘evolution’, however, refers to both theprocesses of evolution and the product of evolution, the history ofevolution as represented by the tree of life (Hull, 1989, p. 224). Thefield of evolutionary biology studies the processes that lead toorganic diversity and concerns itself with the study of the history of

the organic diversity. Evolutionary theory not only aims to explainthe high degree of adaptedness to their living environments thatorganisms exhibit. It also aims to explain the observed diversity ofliving things. If evolution is to be a central theme within biologyeducation then it is not enough to focus on the processes of evolu-tion. It is the product, the phylogenetic tree, that represents theobjects of study themselves and shows how they are related in time.

While the teachers referred to evolution as central theme withinbiology education, it is obvious that they struggled with the inte-gration of evolutionary theory into biology education. The inter-viewees expressed their concerns regarding the structuring ofbiology education. They referred to the sequence in which evolu-tionary theory, the evidence and the processes, should be taughtand to the fact that the students need some elementary knowledgebefore they can begin to understand evolutionary theory. Further-more, the teachers remarked that evolution could be understoodonly at the end when all the biological knowledge is broughttogether. However, prior to this the students should be introducedto the theory of evolution with the help of little pieces of infor-mation included in other topics. Consider the following quotationfrom interview VI:

The theory of evolution is a thread in the background. However,it might become clear to the students for the first time when thematerial that has been studied is brought together, when oneteaches a unit on evidence for evolution. This comes often toolate; one has often this compartmentalized way of thinking.When one does not go beyond the boundaries, for example withexercises or with small bits of information, then it is difficult forthe students to pick out their knowledge from the differentsubjects and to connect them to one another.

This teacher observed that an evolutionary thread, which bindsall the different themes within biology together and stays in thebackground where only the teacher can see it, is not enough. It isimportant that the connecting thread is made explicit for thestudents throughout the curriculum in order to avoid that studentsstore information on the various topics in a compartmentalizedway without connecting the information to one another.

The content analysis led to the deduction of a category named‘The nature of evolutionary theory’. The interviewees displayeda variety of conceptions concerning the NOS (However, it should bekept in mind that probably there is no such thing as the NOS, in thesense of a singular nature shared by all fields of science.). Thismanifested itself in diverse conceptions concerning the evidencefor evolutionary theory. The views ranged from no evidence, onlycircumstantial evidence to a lot of evidence and from differenthypotheses to just stories. Consider the following quotation frominterview IV:

I have a problem with palaeontology in education, because itonly consists of stories. It is very hypothetical and there aremany different possible hypotheses. The risk is that, themoment in which evolution becomes ‘soft’, the students willdevalue it more easily and therefore it is important to take upthe ‘hard’ aspects, that is, the question how Lamarck and Darwincan be experimentally tested.

The quotation above represents an explicit view on the evidencefor evolutionary theory. Palaeontology is just stories. The ‘hard’aspects of evolution are those that can be experimentally tested: forexample, the study of natural selection in Darwin’s finches by Grantand Grant (described in Weiner, 1994). These ‘hard’ aspects that canbe experimentally tested are the focus of most contemporarynatural science: In explanations of phenomena the focus lies ongeneral principles, not on unique unrepeatable events, However,Gould (1989) has suggested that the outcome of evolution cannot

5 The scenario question 2 concerning fitness that was taken from the ConceptualInventory of Natural Selection developed by Anderson et al. (2002) had to be taken

E.M. van Dijk / Teaching and Teacher Education 25 (2009) 259–267 263

be predicted from general principles like natural selection alone,because small changes in preceding events could lead to a differentoutcome. Gould (1989) expressed this in his ‘tape of life’ metaphor:If we rewind the tape of life and replay it again the outcome wouldbe entirely different. The outcome of evolution can only beexplained after the fact in the form of a narrative, which containslaw-like principles and, most importantly, historical particulars.Such narrative explanations aim to explain single events bydescribing a sequence of causally related events, which have led toa certain outcome (Goudge, 1961). For example, a whale seems tobe fully adapted to living in water. However, the fact that a whalehas a rudimentary pelvis can only be explained by including thehistorical particulars, the details in the explanation, such as theexistence of extinct whales, like Basilosaurus, with leg bones. Thesenarrative explanations are not just stories. Molecular data,homologies, vestigial organs, biogeography, and fossils provide theindirect evidence for the reconstruction of the history of life.

In their review of NOS studies Abd-El-Khalick and Lederman(2000) also observed that teachers possess inadequate conceptionsof NOS. Furthermore, Rudolph and Stewart (1998, p. 1076)remarked that: ‘‘problematic has been the tendency for scienceeducators to use the physics model [that is focussed on laws] in thedevelopment of curriculum intended to address general issuesconcerning the nature of science, thus perpetuating a misunder-standing of scientific method that may foreclose the effectivelearning of evolutionary biology.’’

A second manifestation of different conceptions concerning NOSis that the teachers displayed various views on what a theory is; oneteacher referred to an explanatory model while a second teacherstated that the theory of evolution is ‘just a theory’. Alters andNelson (2002), for example, also reported that there is confusionover the term ‘theory’ among the general American public.Consider the following quotations from interview VIII and III:

That it is, in principle, just a theory. We find that in biologyeverywhere, that it, in principle, can be replaced by somethingelse.

Another teacher formulated his view that:

The nature of a theory is clearer in biology. I think it is veryimportant to show the students that the natural sciences deliverexplanatory models that can explain our world and can makegood predictions, but that they are not truths.

In the first quotation a common pre-scientific conception can beidentified. The teacher used the term ‘theory’ in an informal sense.The everyday meaning, being a proposal, a hunch or a guess, isconfused with the scientific notion of theory. In science the term‘theory’ means something different. A scientific theory can bedescribed as an explanatory model that consists of an interrelatedset of well-confirmed hypotheses. It is interesting to observe thatthe teacher who stated that evolutionary theory is just a theory alsoremarked that creationists have a counter-argument for everyevolutionary argument, which makes teaching difficult. The resultsof the PCK-study concerning the topic of creationism further showthat the interviewees wanted to argue against it or they aimed toshow that religion is a different perspective.

out of the data analysis. The conceptual analysis on evolutionary theory has shownthat this question is not correct because fitness is defined as the actual reproductivesuccess of a particular organism. However, since the reproduction of an individualorganism is affected by chance to an unknown degree, it is meaningless to talkabout the fitness of an individual organism (lizard A or B). Because fitness is anexplanatory concept in evolutionary theory it must be linked to evolutionarycauses, and fitness differences between two identical organisms cannot be a matterof mere chance without any difference in evolutionary factors to which theorganisms are subject. Fitness does not refer to the reproductive success ofparticular individual organisms, but to the reproductive success of a certain type oforganism (Beatty, 1992). This is important, as students often have a conceptionof fitness as a property of individual organisms.

5.2. RQ2, ‘students’ pre-scientific conceptions’ and RQ3, ‘subjectmatter representations’

RQ2 and RQ3, concerning the knowledge and beliefs thatteachers have about students’ conceptions and the teachers’knowledge of ways in which these problems can be solved,respectively, are strongly related to one another and are thereforedescribed together in this section. The results of both research

questions are discussed in relation to the available literature onevolutionary theory and pre-scientific conceptions of evolution, asis explicated in the ERTE-model (Fig. 1).5

The results of RQ2 show a wide variety of problems that thestudents have in relation to evolutionary theory. The results of RQ3show some examples – common textbook examples, metaphorsand analogies – that the teachers use in reaction to the students’pre-scientific conceptions and problems concerning evolutionarytheory. The scenario questions concerning variation, adaptationand common descent provided interesting insights into theteachers’ PCK. The responses to the open interview questions didoften, except in the case of selection and deep time, not providea connection between the students’ conceptual problems and theteachers’ subject matter representations.

5.2.1. VariationIn reaction to scenario question 1 concerning variation the

interviewees observed that the students focus on the similaritiesbetween members of a population instead of on the variation. Theteachers expected their students to describe organisms in a pop-ulation as being nearly identical. Additionally, the intervieweesobserved that the students have problems understanding thepopulation concept and they related the students’ awareness ofvariation to their familiarity with the organism. Consider thefollowing quotation from interview III:

All lizards look the same, like most city kids would say that allcows look the same.

A comparison with the research literature on students’conceptions confirms the teachers’ observations, that studentsoften do not see the importance of the phenomenon of intra-species variation for the process of evolution (Bishop & Anderson,1990; Brumby, 1979; Samarapungavan & Wiers, 1997). This neglectof the phenomenon of intra-species variation appears to springfrom a predisposition to an essentialist way of thinking. Cognitivedevelopment research claims that essentialism or typologicalthinking is a heuristic device used by children and adults fromdifferent cultural backgrounds (Gelman, 2003). Essentialistthinking is highly problematic in the context of evolutionary theorybecause it is in conflict with population thinking.

The PCK-study also shows that the interviewees expected theirstudents to have difficulties with understanding that variationoriginates through random mutation. Biological variation originatesin mutations caused by errors in the copying process of genomes.As such copying errors are random events, understanding howrandom processes work is important for understanding biologicalvariation. Anderson and Wallin (2006) observed that the studentshave difficulties accepting random processes. They find it difficultto believe that chance plays such an important part in the comingabout of the organismal diversity that we see today. Furthermore,Bishop and Anderson (1990) observed that students often donot distinguish between the random mutation process and the

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non-random process that leads to adaptation. Students oftenbelieve that a species adapts as a whole to the environment insteadof understanding adaptation as a combination of a random processthat causes variation within a population and a non-randomprocess that leads to adaptation of the population. In relation to thisproblem one of the interviewees observed that even if one knowsthat mutations are random, it is very difficult to bring this aspectinto a complete concept of evolution.

In reaction to the students’ neglect of variation the teachers triedto make students aware of the existing variation within a pop-ulation. The interviewees chose a personal approach, for example,by making the students aware of the existing variation within theirown classroom. The teachers formulated analogies like a shepherdwho knows his sheep, or they tried to make the variation morevisible by using pictures, distribution graphs or examples like wildhorses or African wild dogs. One teacher called upon the students’everyday experience because nobody thinks that the variety thatexists within their own family is goal directed i.e., non-random. Inrelation to the causes of variation one teacher observed thatmutation is often seen to be the only cause of variation and hereminds us that recombination is also an important factor.

The teachers’ responses focused foremost on the students’unawareness of variation within a population. The problem withthe population concept was addressed less often in the teachers’responses to the students’ problems with variation. One teacher,however, took the population concept as starting point. The teacherobserved that students must understand that a population isa hereditary community. According to what is commonly called‘population thinking’, individuals are important and uniquemembers of populations, while the variation between individuals iswhat allows for natural selection to occur. Thus, biological pop-ulations are not so much groups of similar organisms as they aregroups of organisms between which traits are being inherited. Oneof the interviewees suggested further that it is important to makestudents aware of their own predisposition toward essentialistthinking, which leads to a view of populations as groups of similarorganisms.

The scenario question on variation gave us an impression of theteachers’ PCK. The question provided a direct link between theproblem, in this case essentialist thinking, and the way the teacheraimed to solve the problem by making the students aware ofexisting variation. The open sub-questions concerning variation andcauses of variation provided us with an overview of other problemsthat the teachers’ observed, for example concerning the random-ness of mutation. In case of the open interview questions the linkbetween the observed problems and the subject matter represen-tations that were used was not always clearly stated. Descriptions ofthese, often common, textbook examples like Darwin’s finches andskin colour were therefore left out of the discussion.

5.2.2. AdaptationIn accordance with the research literature concerning adapta-

tion the interviewees referred to the goal-directedness of students’ideas and they described the students’ conceptions as ‘Lamarckian’.Consider the following quotation from interview V:

The argumentation is often really Lamarckian: They simply needto learn to catch faster and therefore they have developed bettergenes and they pass these on.

The meaning of the term ‘Lamarckian’ as used by the teachers isoften not clear or not correct. Confusion concerning the meaning ofthe term ‘Lamarckian’ has also been observed in the researchliterature (Kampourakis & Zogza, 2007). The term ‘Lamarckian’ isassociated with two concepts from Lamarck’s theory, use/disuseand the inheritance of acquired characters, and two non-Lamarckian concepts, change due to final cause and change

imposed by need. Lamarck’s theory entails that environmentalchange causes new needs that determine how the body is used, anduse or disuse causes some body parts to develop or wither away(Bowler, 2003). Lamarck does not refer to a need-driven purposefulchange, as the above quotation suggests.

In reaction to scenario questions about how a feature evolves,respectively, how the ability to run fast evolved in cheetahs or howblind cave salamanders evolved from sighted ancestors, the teachersexpected the students to refer to some sort of training effect, disuse,and need. Recent studies on students’ conceptions and cognitivedevelopment have shown that students often display teleologicalassumptions when they are asked to explain adaptations or bio-logical properties (Kampourakis & Zogza, 2007, 2008; Kelemen,1999, 2003). In other words, an end or a goal forms the basis forstudents’ explanations of change. Students, for example, refer toa need to run fast for food (Bishop & Anderson, 1990). Furthermore,studies in the framework of the ER-model showed that studentconceptions on adaptation are deduced from their own experience,i.e., the goal directed insights and actions of humans (Baalmann,Frerichs, & Kattmann, 1999; Kattmann, 2008). Research alsoconfirms the teachers’ observations that students’ refer to use/disuse in order to explain how a certain feature evolved in a pop-ulation (see for example Bishop & Anderson, 1990; Kampourakis &Zogza, 2007). Bishop and Anderson (1990) suggest that the students’explanations imply that such a trainings effect can be inherited.

In reaction to the scenario questions, the interviewees oftenresponded with examples such as: If a man trains his muscles, doeshis newborn child have strong muscles too? Or, when we are ina dark cave for a long time, why don’t we lose our eyesight? Theseanalogies give us insight into the teachers’ PCK concerning adap-tation. They show us where the teacher thinks the problem lies:These responses focus on the aspect of inheritance of acquiredcharacter that is implied by the students’ answer. Analogies like ‘‘Ifa man trains his muscles, will his newborn child have strongmuscles too?’’ aim to show that acquired characters are notinherited. However, analogies like these do not take into accountthe problem that students only see the advantage for the individualorganism. Analogies like these might even strengthen such pre-scientific conceptions. Research has shown that students use theterm ‘adaptation’ often in its everyday meaning referring to indi-vidual change (Bishop & Anderson, 1990; Hallden, 1988). It has alsobeen observed that students have problems understanding thatdifferent evolutionary processes work on different organizationallevels (see also Boersma & Schermer, 2001). For example, Brumby(1984) suggests that: ‘‘Students seem to be extrapolating fromchanges (which they call ‘‘adaptations’’) seen within the lifetime ofan individual to account for changes seen in populations selectedover many generations’’.

5.2.3. SelectionThe open sub-questions concerning selection provided us with

an overview of problems that the teachers’ observed. In some casesthe teachers made a connection between the observed problemsand the subject matter representations that were used.

The aforementioned problem concerning the organizationallevels was also observed for selection. The students often do notunderstand that selection works on the individual level and not onthe species level. In addition, the interviewees discussed a numberof problems and possible solutions. Firstly, that the students oftenhave a mono-causal conception of selection. In reaction to thisproblem skin colour was suggested as an example, because morethan one selection factor plays a role here. Secondly, the studentsthink only in terms of ‘life’ or ‘death’. They do not think in terms of‘proportions’ of organisms with a certain trait that increase ordecrease in a population in a particular situation. In reaction, theteacher used the Galapagos finches as an example of competition

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for food. In addition to the common examples like Darwin’s finches,skin colour, or the peppered moth, one interesting approachmentioned is the comparison of two examples, the peppered mothand dog breeding. The teacher observed that the students say thatman selects the dog and nature selects the peppered moth. Thiscomparison can be used to discuss the students’ conception thatnature selects. For example, Kampourakis and Zogza (2007, 2008;see also Bishop & Anderson, 1990) observed that students refer toexternal agents like nature or God and internal agents like theorganism, which consciously adapts to the environment, instead ofnatural selection in their accounts of biological phenomena.

5.2.4. Common descentIn reaction to scenario question 5, concerning the classification

of whales, teachers mostly referred to the traits of the animal ascriteria for classification. Consider the following quotation frominterview I:

They [the students] say, they [the organisms] have characteris-tics that can be used on land and in water and therefore we takethese features for classification. They do not approach it evolu-tionary but they take the combination of characteristics asstarting point and afterwards this combination has a history,which you can comprehend. So that is exactly how one shoulddo that.

The reference to organismal features as criteria for classificationimplies that the teachers are not aware of the fact that the featuresare only an indication for classification and that organisms aregrouped because they share a most recent common ancestor(MRCA). The difference between the scientific way of classificationand the everyday classification by students is that there is only onecriterion for classifying organisms scientifically, namely the mostrecent common ancestor (MRCA). If young students can choosefreely, they often use habitat and way of movement as criteria toclassify organisms; for example, young students often think thatwhales are fish and not mammals, as both whales and fish live inwater and have similar ways of swimming (Kattmann, 2001).Several interviewees confirmed the existence of these pre-scientificconceptions.

The concept of ‘MRCA’ is one of the evolutionary-historyconcepts that appears to be difficult to understand for students. Forexample, students harbour a serious misunderstanding concerninghuman ancestors (Alters & Nelson, 2002). The problem with thestudents’ conceptions concerning the human ancestor was,according to the interviewees, that the students often make nodistinction between the ancestor of apes and humans, and modernapes. The students often think that humans are descendants ofcontemporary species of apes instead of having a MRCA. Theteachers used fossils to show how species evolve from a commonancestor. But when the students see what fossil remains of thehuman species are available, they are very disappointed and critical.

5.2.5. Deep timeThe results show that time was seen to be a problematic concept

for students. For example, one teacher called it the biggest problembecause, if we can only see a small period of time, it is as if nothingchanges. Gould (1987) observed that ‘‘deep time is so alien that wecan really only comprehend it as metaphor. And so we do in all ourpedagogy.’’ The interviewees tried to visualize deep time in theirteaching by using metaphors like a time line or a clock. However,research suggests that the use of metaphors is not enough to solvethe problem that students have with grasping the concept of deeptime. Trend (2001) observed that learners are more comfortablewith relative time (ranking events in relation to other events) thanabsolute time (actual date of an event) within the context of deeptime. Students should therefore be taught to place a selection of

pivotal events into correct periods of time with an emphasis ondates and duration.

Although the teachers were aware of the problems concerninghistory-of-life concepts like ‘MRCA’ and ‘deep time’, they mostly didnot refer to these concepts as the key concepts for teachingevolutionary theory. We could, however, ask ourselves in how farthe problems with understanding the evolutionary process arecaused by a lack of attention for the history of life or macro-evolutionary processes in teaching.

5.2.6. Attitude towards students’ pre-scientific conceptionsThe interviewees expressed their frustration concerning the

persistence of the students’ pre-scientific conceptions. The analysisof the interviews shows that the teachers referred to students’conceptions in terms of ‘to replace’, ‘to revise’, ‘to knock over’, or ‘toget out’. In contrast one teacher stated: ‘‘to get away from, no not toget away from, that is not achievable, but the reflection on.’’

The assumption that students’ pre-scientific conceptions can bereplaced with scientific conceptions is not compatible with theoutcomes of research on cognitive development. Research con-cerning students’ conceptions and cognitive development suggeststhat the primary cause of students’ learning problems with respectto understanding evolutionary theory consists in predispositionsthat students have before beginning to learn evolutionary theory(see also Rudolph & Stewart, 1998). Pre-scientific conceptionsconcerning, for example, the evolutionary notions of variation andadaptation spring from a predisposition of children and youngadults toward essentialist and teleological ways of thinking (seeGelman (2003) with respect to essentialism and Kelemen (1999,2003) with respect to teleological thinking). Such predispositionsmight exist because they are useful or appropriate in everyday life –that is, in contexts other than thinking about biological evolution –and children have picked them up there, or they might simply beinnate (as Gelman (2003), for example, suggested for essentialistthinking). Additionally, everyday experiences, for example that theuse of muscles makes them stronger, and the everyday meaning ofterms like ‘adaptation’ and ‘fitness’ will keep their value within aneveryday context (cf. Hellden & Solomon, 2004). These consider-ations call for a different perspective on students’ conceptions.Instead of trying to change the students’ conceptions concerningevolutionary theory it would be more constructive to reflect on thestudents’ ideas in relation to the different contexts, everyday andevolutionary theory, within the teaching of evolution.

6. Conclusions and outlook

The answers to the open interview questions concerning the‘subject matter knowledge for teaching’ (RQ1) provided us withinteresting insights into the teachers’ PCK concerning evolutionarytheory. The interviewees displayed different views on the nature ofevolutionary theory. The teachers’ conceptions of the evidence onwhich the theory of evolution is based are diverse and do notalways reflect an appreciation of the historical nature of biology.Furthermore, the teachers referred foremost to micro-evolutionaryprocesses, mutation and selection, as the most important themes,while history-of-life concepts like ‘MRCA’ and ‘deep time’ are notseen to be key concepts within the teaching of evolution, althoughthey cause many problems for students. The nature of science andespecially the historical nature of biology should therefore be givenmore attention in teacher education.

The answers to the open interview questions concerning thestudents’ pre-scientific conceptions (RQ2) provided us with inter-esting insights into teachers’ understanding of students’ concep-tions and problems concerning the theory of evolution. The studyfurther provided information on the teachers’ attitude towardstudents’ pre-scientific conceptions. The teachers’ assumption that

Core idea:3. What are the difficulties and challenges connected with teaching this idea?4. What do you know about students’ thinking that influences your teaching of this

idea?5. What particular cases, phenomena, situations, experiments, people, events can be

used to make the content in question interesting, worth asking questions about,accessible, comprehensible, conceivable for the children at their level and grade?(Have you sometimes tried out other strategies for teaching this core idea?)

You present the following questions, 1–6, to a student who has been taught the

theory of evolution but failed to acquire a basic understanding of evolution.

What answers do you expect the student to give, given that he or she does not

understand evolutionary theory? (What would the good answer be?)

How would you react to the answer that was given by the student?

Question 1. Populations of lizards are made up of hundreds of individual lizards.

Which statement describes how similar they are likely to be to each other?

A. All lizards in the population are nearly identical.

B. All lizards in the population are identical to each other on the outside, but there

are differences in their internal organs such as how they digest food.

C. All lizards in the populations share many similarities, but there are differences in

features like body size and claw length.

D. All lizards in the population are completely unique and share no features with

other lizards.

Question 2. Fitness is a term often used by biologists to explain the evolutionarysuccess of certain organisms. Below are descriptions of four fictional femalelizards. Which lizard might a biologist consider to be the ‘‘most fit’’?

Lizard A Lizard B Lizard C Lizard DBody length 20 cm 12 cm 10 cm 15 cmOffspring surviving to adulthood 19 28 22 26Age at death 4 years 5 years 4 years 6 yearsQuestion 3. Cheetahs are able to run faster that 60 miles per hour when chasing prey.

How would a biologist explain how the ability to run fast evolved in cheetahs,assuming their ancestors could only run 20 miles per hour?

Question 4. Cave salamanders are blind (they have eyes which are non-functional).How would a biologist explain how blind cave salamanders evolved from sightedancestors?

Question 5. What kind of animal is a whale? Is it a fish, an amphibian; a reptile ora mammal? How would a biologist classify a whale?

Question 6. What would the ancestors of man look like?

E.M. van Dijk / Teaching and Teacher Education 25 (2009) 259–267266

students’ conceptions of evolutionary theory can be replaced is notcompatible with the outcomes of recent research on cognitivedevelopment. This shows that the development of an adequateattitude toward students’ pre-scientific conceptions should be animportant aspect within teacher education. A more useful attitudewould be to ask how students’ conceptions on evolution can beused in a constructive way and can be reflected upon within thecontext of the theory of evolution.

Answering RQ3 concerning the teachers’ knowledge of subjectmatter representation proved to be more problematic. A problemwas that in reaction to the open interview questions the linkbetween the observed problems and the subject matter represen-tation that were used was not always clearly stated. The teachersgave many examples of common textbook examples that they usedin their teaching like, for example, Darwin’s finches, skin colour, orthe peppered moth. These examples, however, were mostly notdirectly related to the specific conceptual problems that studentshave with understanding evolution. An additional problem thatwas encountered during the study was a lack of detailed descrip-tions of instruction that the students’ received, in empirical reportsof studies concerning evolution education research (see also Pass-more & Stewart, 2002). The discussion of teachers’ ways to react tostudents’ conceptions would have benefited from more detaileddescriptions of instruction on evolutionary theory in the educa-tional research literature.

The scenario questions proved to be the most effective interviewitems in order to acquire a detailed picture of teachers’ ways toreact to students’ pre-scientific conceptions and problems con-cerning evolutionary theory. The scenario questions forced theteachers to react to specific well-known conceptual problems. Forexample, the analogies with which the teachers responded to thestudents’ conceptions on adaptation provided an interestingpicture of the teachers’ PCK. In a follow-up study more scenarioquestions should therefore be included in order to acquire a moredetailed picture of teachers’ ways to react to students’ problemswith evolutionary theory.

Acknowledgements

I would like to thank the teachers for their participation in thisstudy. I would also like to thank Ulrich Kattmann and ThomasReydon for their valuable comments in the course of this researchand on this manuscript.

Appendix. Interview protocol: A PCK-study on evolutionarytheory

Part 1: Two questions concerning your background

1. What education/training have you received? (subjects; level; teacher trainingcourses)

2. What teaching experience do you have? (number of years; level; subjects)

1. Can you recall remarkable – critical or fruitful – incidents during your teaching of

Part 2: Questions concerning teaching evolution

0a. In which grade(s) do you teach evolution (as a separate topic or integrated inother themes)?

0b. How much time do you spend on teaching evolution in the different grades?0c. What status has the teaching of evolution within the biology education for you?0d. Which literature will be used by the students during the lessons?0e. Which literature (books, journals) do you use for the preparation of your

instruction?1. What do you intend the students to learn about evolution, what are the important

concepts, or core ideas?2. Why it is important for students to know these core ideas?

Part 3: Questions concerning the instruction on the topic ofevolution pro core idea

Part 4: Scenario questions

Part 5: Closing questions

evolution?2. Can you mention items concerning the teaching of evolution that you find

important but have not been discussed during this interview?

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