Examining pedagogical knowledge content on mitosis in a University context

Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 79 Examining pedagogical knowledge content on mitosis in a University context N. González*1, A. Rossi2 1Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata. 60 y 118, 1900 La Plata, provincia de Buenos Aires, Argentina. 2Facultad de Ciencias Médicas, Universidad Nacional de La Plata. 60 y 120, 1900 La Plata, provincia de Buenos Aires, Argentina. * Corresponding author: Email: nvgonza[email protected]m. +54 221 4236663 Received: 2016-05-23; Accepted: 2016-08-15 Abstract Mitosis is a process of cell division occurring in eukaryotic organisms. Students from many countries experience difficulties learning this science topic, and its teaching demands substantial effort. Effective teachers develop a wide range of knowledge types to successfully transform science matter for students; this transformation of knowledge has been conceptualized as pedagogical content knowledge (PCK). In this study the PCK of two University teachers on mitosis was explored. As informed by the instruments employed (Content Representation and Pedagogical (CoRe), and Professional experiences Repertoires, analytical rubric (PaP-eR), and semi-structured interviews) both participants’ PCK on mitosis can be characterized as incomplete, however not identical. PCK evolves throughout the professional practice so, in a context mostly limited to a traditional teacher-centered transmission of knowledge such as the university, development of teachers’ PCK emerges as a strategy to reorient the teaching of mitosis to modalities based on the construction of scaffoldings to facilitate students’ learning. Keywords Pedagogical content knowledge (PCK), mitosis, university, Content Representation questionnaire (CoRe), Professional and Pedagogical experience Repertoire (PaP-eR) Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 80 1. Introduction Mitosis is a process of nuclear division in eukaryotic cells that occurs when a single parent cell divides resulting in generally two identical daughter cells each containing the same number of chromosomes and genetic content as that of the original cell. During cell division, mitosis refers specifically to the separation of the duplicated genetic material carried in the nucleus. This biological process is located at the intersection of unifying topics of biology i.e. continuity, in connection to reproduction, and development of cells and organisms for it relates to growth, tissue repair and regeneration. Learning mitosis is also fundamental to the understanding of transmission genetics and molecular biology (Ayuso and Banet; 2002; Locke and McDermid, 2005). Students from many countries experience difficulties particularly when discriminating biological concepts such as chromosomes, chromatids, diploid cells, and struggle to make appropriate and meaningful connections between mitosis and genetic information (Lewis, Leach and Wood-Robinson 2000; Dikmenli, 2010; Chattopadhyay, 2012; Çimer, 2012). Different strategies have been proposed to teach this topic, i.e. interactive videos (Baggott and Wright, 1996), chromosomal modeling by using pool noodles (Locke and McDermid, 2005), and socks (Chinnici, Neth and Sherman, 2006), computer-based activities (Tsui and Treagust, 2013), Web-based curriculum units (Williams, Montgomery and Manokore, 2012), and also role-playing (Chinnici, Yue and Torres, 2004). In large university classes, lecturers apply to visualizations of this cell division, among many those supported on PowerPoint® slide shows (González et al., 2014c). More than three decades ago teachers rated mitosis as one of the most difficult topics to teach (Finley, Stewart and Yarroch, 1982). As students experience difficulties when learning this topic, its teaching demands considerable effort for novice (Yip, 1998) or even experienced teachers (Knippels, Waarlo and Boersma, 2005; Oztap, Ozay and Oztap, 2003; González and Rossi, 2015). Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 81 Many studies conclude that teachers’ performance in the classroom is one of the most important factors in students’ academic achievement. Thus, effective teachers develop and display a wide range of knowledge types to successfully transform science matter for students (Kind, 2009). Magnusson, Krajcick and Borko (1999) define this type of knowledge as pedagogical content knowledge (PCK): “the transformation of several types of knowledge from other domains” (p. 96). Our research team has been working in the assessment of teachers’ PCK on meiosis, a eukaryotic type of cell division process that shares with mitosis similar difficulties as those mentioned above and challenges for both students and faculty. We have successfully employed the Loughran, Mulhall and Berry (2004) Content Representation and Pedagogical, and Professional experiences Repertoires (CoRe and PaP-eRs, respectively) to characterize the PCK of pre-service and in-service secondary teachers on meiosis (González and Rossi, 2014a). In the same line of work, we employed a rubric to document university cell biology teachers’ PCK focusing on the PowerPoint® presentation they used in their classes (González et al., 2014c). Few works examine teachers’ PCK on mitosis and are mainly focused on secondary education. The objectives of this study were to document the PCK of two cell biology university teachers on the subject of mitosis following the methodology proposed by Loughran et al. (2004), and complementarily to assess their PCK as displayed in a set of slides. The research questions guiding the investigation were: What components of PCK on mitosis can be identified in a University context? What PCK content can be identified by an analytical rubric assessing a PowerPoint presentation on mitosis? Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 82 2. Conceptual framework Pedagogical content knowledge (PCK) as proposed originally by Shulman (1986) includes “the most powerful analogies, illustrations, examples, explanations, and demonstrations in a word, the ways of representing and formulating the subject that makes it comprehensible for others” (1986, p. 9). PCK has been interpreted by scholars in many ways addressing different features of it. Kind (2009) reviews a variety of models of PCK including those that follow Shulman‘s line of thought explicitly and others that draw on empirical research findings or on principles from psychology. The Magnusson et al. (1999) model is within the former group. These researchers conceptualize PCK as consisting of five components: (a) orientations toward science teaching, (b) knowledge and beliefs about the science curriculum, (c) knowledge and beliefs about students’ understanding of specific science topics, (d) knowledge and beliefs about of assessment in science, and (e) knowledge and beliefs about instructional strategies for teaching science. In 2012, international research teams gathered at a PCK summit and produced the following consensus definition: PCK is a “personal attribute of a teacher, considered both a knowledge base and an action. It is the knowledge of, reasoning behind, planning for, and enactment of teaching a particular topic in a particular way for a particular reason to particular students for enhanced student outcomes” (Carlson and Gess-Newsome, 2013). As stated by participants at the PCK summit, teacher professional knowledge bases are the backbone of the profession thus including assessment knowledge, pedagogical knowledge, content knowledge, knowledge of students, and curricular knowledge. More interestingly, as depicted in Figure 1, in the classroom practice, PCK interacts with the classroom context, and with two sets of amplifiers and filters. Amplifiers increase the potential of an idea being accepted or an action being implemented whereas filters can extinguish good intentions or ideas. One set of amplifiers and filters comprises teachers’ beliefs and orientations; the other set relates to students’ beliefs, prior knowledge, and behaviors. Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 83 Figure 1. The teacher professional knowledge bases consist in a series of knowledges. Topic Specific Professional Knowledge is derived from a cross section of the Teacher Professional Knowledge Bases for a specific topic. There are two sets of amplifiers and filters, the first set falls between topic specific subject matter professional knowledge and Classroom Practice; the second set falls between the latter and students outcomes. Classroom Practice is the context in which PCK exists. Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 84 3. Methodology 3.1 Context of the study The study took place in the Veterinary College, University of La Plata, Argentina during a 3 h weekly instruction period of a Cell Biology course. It is a mandatory course for first year students. Mitosis is a topic included in the course curriculum that is focused mainly on cytological aspects and corresponds to a teaching sequence after dealing with basic genetics, i.e. DNA replication, transcription, protein synthesis, and DNA recombination. It is presented to the students as the final phase of the cell-cycle. Mendelian genetics are covered in a separate second year course. 3.2 Participants Two teachers (Sylvia and Juliette, pseudonyms) participated voluntarily in the study. Both graduated as Veterinary Medical Doctors and earned their Ph.D. where the study took place and have had very little non-systematic teaching training. They have taught the Cell Biology course as teaching assistants since 2006, and are thoughtful about their classroom performance and highly appreciated by their students and colleagues. Sylvia’s and Juliette’s classes had 30 and 21 students, respectively. 3.3 Instruments PCK researchers have developed an array of methodologies and techniques to gain knowledge into this construct, e.g. paper and pencil assessments such as open-ended and multiple choice questions, concept maps, drawings, interviews, video observations of real instruction, classroom observations, and very commonly, some kind of combination of the previously mentioned (Baxter and Lederman, 1999; Borowski, Carlson, Fischer, Henze, Gess-Newsome, Kirschner and Van Driel, 2012). In this study four instruments were employed. Two of them corresponded to the Loughran et al. (2004) CoRe and PaP-eR tools. The CoRe consisted of eight questions (see Results Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 85 section). The CoRe questionnaire was presented to the participants and discussed to orientate the elaboration of responses after the class observation. Later, it was sent by email, and answers received a week later by the same via. The PaP-eR was developed from observations of classes, one of the sources proposed by Loughran et al. (2004). The researchers, as non-participant observers, took detailed field notes and produced shortly afterwards a written version of the material originally gathered at the class. The third instrument employed was the analytical rubric (González et al., 2014c). It comprised a content dimension focused on PCK whereas the other dimensions aimed to the design of the slides as instructional materials. Briefly, the rubric covered the following dimensions and indicators:  Content: core conceptualizations (identified by a previous inquiry with expert colleagues), logical sequencing, relations between core conceptualizations, transition between concepts, data and/or examples inclusion.  Organization: introduction-body-conclusion format, transition between slides, and internal coherence.  Information: quantity, quality, and pertinence of data.  Graphic aspects: quality, quantity, relevance and creative use of photographs, graphics and tables.  Textual aspects: grammar and spelling, terminology, quality and extent of texts and titles. Four levels were established for the assessment: exemplary, proficient, acceptable, and unacceptable. Each indicator was assigned 3, 2, 1 or 0 points, respectively. The PowerPoint® slides were kindly provided by the teachers. The assessment was performed independently by the researchers, and latter discussed so that scorings were consensual. Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 86 The fourth instrument included in this study was a semi-structured interview. Sylvia and Juliette were interviewed individually to review their answers to CoRe, and specific aspects of their classes and presentation slides. Then, the final analysis of the CoRe responses, the writing of PaP-eR and the scoring by the rubric were performed. 4. Results 4.1 CoRe For clarity, Sylvia’s and Juliette’s responses are presented together with the questions. 1. What do you intend the students to learn about this topic? Our two participants’ central ideas are presented in Table 1. Table 1. The two participant’s central ideas on mitosis. Sylvia´s central ideas Juliette´s central ideas • Mitosis is a regulated process that occurs in unicellular and multicellular eukaryotic organisms. • Mitosis occurs in somatic cells e.g. keratinocytes (epidermal cells), hepatocytes (liver cells). • Every cell originates from another existing cell like it (Virchow´s Omnis cellula e cellula). • The chromatids of a replicated chromosome separate in the anaphase. • In dividing cells, mitosis is the culmination of their cell-cycle. • Daughter cells in mitosis are genetically identical to the parent cell and the reasons for this. • In mitosis, the parent cell transfers its genetic material previously replicated to daughter cells. • The comparison of cell division by mitosis and cell division by meiosis. • Daughter cells originated by mitosis maintain the diploid number of chromosomes of the parent cell. • The sequence of events in mitosis is continuous; it is divided into stages mainly for didactic reasons. Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 87 2. Why is it important for the students to know this? Sylvia stated that mitosis is a basic knowledge related to several biological concepts such as haploid and diploid cells, and processes like cell division by meiosis, and diploid chromosomal number restoration at fertilization. She highlighted that mitosis also provides knowledge basis for the understanding of molecular and cellular foundations of many diseases in which cell proliferation is altered. Juliette’s answer referred to the role of mitosis in animals i.e. in development, growth, reparation and regeneration processes; she also mentioned its role in the reproduction of unicellular organisms. 3. What else do you know about this idea (that you don't intend students to know yet)? Sylvia referred to a large body of knowledge on mitosis regulation, e.g. cascades of protein phosphorylation, the groups and subtypes of cyclin proteins family, and the metaphaseanaphase checkpoint. She also linked failures of the cell-cycle machinery to cancer development. As her colleague, Juliette listed a number of molecular aspects of mitosis, the majority of them mostly in relation to chromosome structure (cohesines, condensines). She considered these topics should be addressed in the lectures given by professors. 4. Which difficulties/limitations are connected with teaching this topic? The main difficulties (items 1, 2, and 3), and limitations (item 4) pointed out by Sylvia and Juliette are summarized in Table 2. Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 94 4.3.2 Assessment by the rubric As it concerned our objective of documenting the participants’ PCK, the assessment was focused on the content dimension. Detailed results are presented in the Appendix. Short descriptive outcomes related to the remaining dimensions were also elaborated and here presented. Content dimension: all core contents (identified by a previous inquiry with expert colleagues) were addressed in both set of slides; subtopics were logically sequenced but each participant’s elaboration differed in qualitative aspects. Connection and transition between concepts were achieved in both presentations by means of similar precise links. Sylvia’s slides received a higher score on depth of content due to a more extended elaboration on cell-cycle regulation based on one of the learning goals of the class 1 . Her score was also higher for the variety of examples she presented to the students. The scores for Sylvia’s and Juliette’s presentations were 17/18 points and 15/18 points for the content dimension, respectively (see Appendix for detailed results). Organization and information dimensions: Sylvia’s and Juliette’s slides alike received the exemplary level. Graphic aspects dimension: both presentations included a similar number of relevant slides to depict the topic. However, Juliette incorporated images from different sources – 1 List the four stages of interphase, and describe the major events that occur during each stage in preparation for cell division. List the checkpoints that regulate the progression of cells through the cell cycle and explain the mechanisms. List the phases of mitosis in a eukaryotic cell, and discuss the major events that happen during each phase. Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 95 books and web pages– in the same slide; such diversity of representations was considered a potential cognitive overload that diminished their pedagogical value. She excluded the use of the video due to time constraints. Sylvia showed the video and revealed a creative use of images for she developed a short time extra in-lecture activity to summarize the phases of mitosis. Textual aspects dimension: the two instructional materials had an appropriate simple design used as a mean to greater clarity; they both were exemplary on all indicators. 5. Discussion In this study the PCK of two University teachers on mitosis was explored. The choice of this topic was based on its disciplinary centrality, and on that it is regularly taught in introductory biology courses. The tools employed were the Loughran et al. (2004) CoRe and PaP-eR, an analytical rubric, and semi-structured interviews. The analyses of the results concerning the CoRes and PaP-eR through the Magnusson’s et al. (1999) PCK components that framed our investigation led to the following appreciations. Orientation toward science teaching. An orientation represents a general way of viewing of conceptualizing science teaching; it is described with respect to the goals of science teaching and the characteristics of the instruction (Magnusson et al. 1999). In reference to the goals of teaching this topic both teachers combined academic rigor and didactic orientations. Their classes were teacher-centered: they presented a body of factual knowledge by explanations and short discussions. Sylvia implicitly drove students to develop thinking processes whereas Juliette directed questions to students to mostly hold them accountable for knowing the scientific information on the topic. Knowledge of science curriculum. This component of PCK consists of two categories: teachers’ knowledge of the goals and objectives for students in the subject they are teaching and their knowledge of what students have learned previously and what they are expected Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 96 to learn later on (Magnusson et al. 1999). Sylvia and Juliette are knowledgeable about the learning objectives for students in this course. They both started the session drawing the students’ attention to them and throughout the lesson made clear connections to topics addressed in previous meetings such as DNA replication and cytoskeleton components. As veterinary medicine graduates, they were able to link mitosis to other courses, i.e. Pathology (Sylvia) and Basic Genetics (Juliette). Knowledge of students’ understanding of science. Two categories of knowledge are included in this third component: requirements for learning specific science concepts, and areas of science that students find difficult (Magnusson et al. 1999). Teaching experience accounts for Sylvia’s and Juliette’s awareness of students’ difficulties on mitosis; they were able to list alternative conceptions, difficulties, and misunderstandings. Although they acknowledged the abstract nature of mitosis, they were not able to explicitly mention requirements for learning this topic. Knowledge of assessment in science. There are two categories of knowledge included in this conceptualization: knowledge of the dimensions of science learning to assess and knowledge of the methods of assessments (Magnusson et al. 1999). Sylvia considered that oral quizzes were suitable for formative assessment in class; she believes individual and written summative evaluation should be implemented after the session. Juliette shares Sylvia’s first idea. They both value the final course evaluation (multiple choice test on conceptual understanding) as the formal assessment but mentioned no alternatives to it. Knowledge of instructional strategies. This component is comprised by two types of knowledge: knowledge of subject-specific strategies and knowledge of topic-specific strategies (representations and activities). Sylvia’s emphasized on the students’ involvement, and as observed in the actual class, she strongly intended her students to participate during the lecture. She mentioned activities dealing with factual knowledge of mitosis; some of them could be valued as topic-specific strategies e.g. simple mathematical calculations dealing with the number of chromosomes and chromatids in parental and daughter cells. Although varied, it is doubtful to conceive that these activities would Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 97 actually engage students. Juliette stated that she has no knowledge of other teaching strategies than lecturing. During the session she intended to promote students’ engagement with the topic by presenting examples related to veterinary medical practice. Rubrics are widely employed as effective assessment tools in science teaching (Allen and Tanner, 2006); in the present work the innovative instrument by González et al. (2014) was applied to our participants’ PowerPoint® presentations to assess their PCK and thus complement their CoRe and the PaP-eR. Two indicators –depth of content and data and/or examples inclusion– provided evidence of components of Sylvia’s and Juliette’s PCK related to the curriculum domain: knowledge of the learning goals of the session and knowledge of what students have learned previously and what they are expected to learn afterwards. Besides the differences detailed in the descriptive aspects, the analysis rendered other remarkable feature. The teaching sequence was prescriptive and encapsulated in the PowerPoint® slides provided by the course coordinator. However, as some modifications were available for teaching assistants to make; Sylvia’s choice rested on the incorporation of slides concerning molecular aspects of cell-cycle regulation thus reinforcing the explanation of academic aspects of this troublesome scientific idea. Moreover, Sylvia included an additional slide about homologues chromosomes, another conflicting issue for students. On the other hand, Juliette included in her presentation supplementary images concerning the stages of mitosis. Sylvia’s emphasis on the molecular aspects of cell-cycle regulation and conceptualization of chromosomes and Juliette’s focusing on the cytological aspects of mitosis and cytokinesis revealed their knowledge of the students’ understanding of specific science topics, specifically topics that students find difficult. Thus, the dimensions related to the slides as instructional materials showed that these teacher assistants chose different ways to represent and cover the content of the session, each highlighting those aspects of mitosis they valued the most relevant for their students and in coincidence of their responses to Co-Re question 2. Few categories of the Magnusson et al. (1999) PCK components were identified in Sylvia’s and Juliette’s Co-Re, PaP-eR, and rubric outcomes consisting mainly in the transformation Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 98 of disciplinary knowledge oriented to the presentation of content, and some factual conceptions about teaching procedures, curriculum and evaluation. At this point, to refine results from the assessments, it is interesting to introduce Talanquer’s perspective (2004) on the PCK; this author argues that teachers’ PCK must be sufficient to:  Identify the main ideas associated with a topic.  Recognize the students’ probable conceptual difficulties and the impact on learning.  Identify questions, problems or activities that require students to recognize and challenge their preconceptions.  Select experiments, problems or projects that allow students to explore central ideas in the discipline.  Build explanations, analogies or metaphors to facilitate understanding of abstract concepts.  Design assessment activities that allow the application of learning in realistic and varied contexts. Viewed in light of Talanquer’s requirements (2004), we believe that both participants’ PCK on mitosis can be characterized as incomplete, however not identical. The greatest concurrence was found in the identification of the main subtopics in the process of mitosis, and the difficulties in its teaching, focusing on some students’ shortcomings. Sylvia’s knowledge and beliefs informed by CoRe were aligned with her transmission-orientated teaching revealed in the PaP-eR. Nonetheless, Sylvia´s central ideas are more numerous and cover a wider range of subtopics, and throughout her class, she continually and systematically re-visited the session’s goals. As evidenced by the rubric assessment and Pap-eR, in a format lecture she made room for a creative use of slides in an attempt to engage her students with the topic. Moreover, in previous study Sylvia’s beliefs and ideas on the teaching of this topic revealed her reflection on action and reflection in action (González et al., 2014b). On the other hand, Juliette was aware of some critical aspects of teacher’s PCK based, as Sylvia, on her classroom experience and her subject matter Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 99 knowledge. She was at all times the driving force in the classroom, and although she explicitly connected mitosis and biological processes related to domestic animals, it failed to captivate her students’ attention. It resulted evident that although both teachers had been receptive towards the incorporation of in-lecture activities as proposed by the course coordinator; their limited knowledge about instructional and assessment strategies shaped their orientations towards science teaching and, mostly they taught as they had been taught. We believe that the differences between Sylvia’s and Juliette’s PCK can be further explained by taking in consideration the filters and amplifiers included in the teacher professional knowledge bases model presented in Figure 1 (Carlson and Gess-Newsome, 2013). Filters and amplifiers comprise teachers’ beliefs, orientations, prior knowledge and context; as a counterpart also students’ beliefs, prior knowledge and behaviors are included as potential filters and amplifiers. Our participants share most of their formative disciplinary backgrounds and teaching experiences but, as noted in the PaP-eR, the climate of the classrooms differed: in Sylvia’s classroom it was more relaxed and, on demand of her students, she devoted time to clarify erroneous or incomplete concepts whereas in Juliette’s session, at certain moments, an air of tension seemed to prevail. The students’ choices to attend to instruction or ignore it, embrace student-centered teaching practices or resist them as possible courses of action became crystal-clear in each classroom and, for Juliette, developed in a filter that diminished her good intentions and actions. Numerous studies concerning effective teaching strategies for mitosis at diverse educative levels reflect its presence and relevance in science curriculums all over the world. However, being PCK a content-specific construct, investigations addressing this topic at universities are practically non-existent. The study reported here explored two University biology teachers' PCK on mitosis and is part of a bigger project; these results encourage us to carry on so knowledge gained from the research program would be built in novel contributions for high quality classroom practice. Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 100 6. Conclusions and implications • The CoRe and Pap-eR presented are autonomous because they illustrate how the PCK is evident by revealing specific aspects of the action in the classroom (Juliette) and reflection on action and reflection in action (Sylvia). • The differences found in the teachers’ PCK are consistent with the characteristics of this construct: PCK is specific to a topic, a teacher and a context.  The analytical rubric provided pre-established performance criteria to make intelligible some aspects of the PCK components from the Magnusson and coworkers’ theoretical framework adopted in this study. Its effectiveness and value as an assessment tool relied in its complementary character to other highly recognized survey instruments as the ReCo and PaP-eR. We would like to close this article with a reflection on the assumption of the PCK as a continuum –from weak to strong– as it entails a second notion: PCK can be strengthened (Gess-Newsome, Carlson, Gardner and Taylor, 2010). The interaction of the components of PCK has been noted to be limited in research with novice teachers (González and Rossi, 2014a); a similar situation has been demonstrated in investigations with preservice teachers (Friedrichsen et al. 2009). Kind (2009) points that PCK remains unnoticed by many science teachers; for instance, as many of our fellow university teachers, Sylvia and Juliette, the two experienced teachers in the present work had never heard the term. Our characterization of the participating teachers’ PCK as incomplete indicates the strong need to pay special attention to the construction of PCK as a way of improving teacher professional knowledge (Kind, 2009; Loughran et al. 2012). Taking in consideration that the PCK of a teacher evolves throughout his professional practice (Olander and Olander, 2013) and, furthermore given the acknowledged role of reflection in the development of science teachers’ PCK (Popovic and Antink, 2010), we highlight the relevance of including in-service training to enhance the professional development of university teachers. Moreover, in a context mostly limited to a traditional teacher-centered transmission of Multidisciplinary Journal for Education, http://dx.doi.org/10.4995/muse.2016.4653 Social and Technological Sciences EISSN: 2341-2593 González and Rossi (2016) http://polipapers.upv.es/index.php/MUSE/ Mult. J. Edu. Soc & Tec. Sci. Vol. 3 Nº 2 (2016): 79-106 | 101 knowledge such as the university, and in line with several investigations that encourage the use of CoRes and PaP-eRs as an strategy to develop and support science teachers’ PCK (Bertram, 2014), we strongly believe that may prompt university teachers to reflect meaningfully on their practice. The PCK development of teachers emerges as a strategy to re-orient the teaching of mitosis to modalities based on the construction of scaffoldings to facilitate students’ learning. Acknowledgements We thank the teaching assistant who participated in this study. This work was supported by grants from the National University of La Plata (Project 11/V216) “La construcción del conocimiento pedagógico del contenido (CPC) y del conocimiento del contenido tecnológico-pedagógico (CCTP) para el proceso de mitosis en profesores universitarios”. 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