Arranging cards to build an organizational model of the elements Joanna Philippoff, Kanesa Duncan Seraphin, Jennifer Seki, and Lauren Kaupp T he periodic table does more than provide information about the elements. The periodic table also helps us make predictions about how the elements behave. Understanding the atomic structure of matter and periodic properties of the elements, as shown in the periodic table, is fundamental to many scientific disciplines. Unfortunately, high school students often view the periodic table as an overwhelming jumble of numbers and letters to be memorized, rather than a model with predictive and explanatory power. This article presents an activity that uses the rich history of the development of the periodic table to promote understanding of how the elements are organized. By arranging three sets of cards, students connect to the individuals in history whose creativity and imagination laid the groundwork for our evolving comprehension of the patterns in nature. This activity, which has strong connections to the Next Generation Science Standards (NGSS Lead States 2013) (see box, p. 49), can be accomplished in as few as two class periods with little prep time or cost. Improving students’ understanding of the nature of science has been an ongoing goal for more than 50 years (Lederman 2007). This activity focuses on three of the nature of science understandings defined by the NGSS: scientific knowledge is open to revision in the light of new evidence, scientific knowledge is based on empirical evidence, and science is a human endeavor (NGSS Lead States 2013). Over the 124 years modeled in this activity, advancements in technology allowed for the discovery of new elements and elemental properties, and scientists modified existing elemental organization paradigms to accommodate the new evidence. Similarly, students in this activity revise scientific explanations based on new evidence as they develop classification strategies for the elements. At the end, students October 2015 43 reflect on their reasoning and compare their organization schemes to those of their peers and historical scientists. F IGUR E 1 Dmitri Mendeleev, the “father of the periodic table.” Element cards Historical lore says that Russian chemist Dmitri Mendeleev (1834–1907) (Figure 1) wrote the weights and properties of the elements on cards and played “chemical solitaire,” organizing them. Although no such cards have been found, the analogy to the popular card game is a useful teaching tool and encourages students to think of multiple ways of classifying the elements. In solitaire, cards are organized by suit and value. Mendeleev developed a periodic table organized by both weight and properties. In this activity, element cards (provided online; see “On the web”) are divided into three sets that correspond to significant advancements in our understanding of how the elements are organized (Figure 2). The colors named below for the card sets correspond to the colors in Figure 2. ◆◆ 44 Set A (1789; green): The elements in the list of simple substances that French chemist Antoine-Laurent Lavoisier (1743–1794) developed that correspond to our modern understanding of elements (N=27). The indicated year, 1789, is when Lavoisier published his table; 27 is the number of elements he listed that correspond to our modern understanding of the term. Set B (1869; gold): The additional elements known at the time that Mendeleev constructed his first periodic table (N=30). The Science Teacher SERGE LACHINOV ◆◆ Chemical Solitaire FI G U R E 2 Historical progression of element organization cards laid on the modern periodic table. Set A (1789) = green, Set B (1869) = gold, Set C (1913) = Blue. (Although highlighted, the lanthanide and actinide series are not included in the activity.) ILLUSTRATION BY BYRON INOUYE. ADAPTED WITH PERMISSION FROM EXPLORING OUR FLUID EARTH (SERAPHIN ET AL. 2015). ◆◆ Set C (1913; blue): The additional elements known when English physicist Harry Moseley (1887–1915) rearranged the periodic table based on atomic number (N=11). This progression of card sets scaffolds the number of elements students have to manipulate at a time, follows historical discovery, and allows students to arrange more familiar elements first. The year 1913 was chosen for the final card set because it allows students to add the noble gases to their element arrangement and “fill in” some of the potential gaps in their models. However, some elements (colored gray in Figure 2) were still “missing” at this time, including, for example, Technetium, atomic number 43, discovered in 1937. Each element card has the element name, chemical symbol, element weight, state at room temperature, valence, and reactivity for elements in groups with similar chemical properties (groups 1, 2, 17, and 18). For example, the alkali metal cards read “reacts vigorously with water,” and the halogen cards read “reacts with metals to form salts” (Figure 3, p. 46). The cards balance historical accuracy with supporting student understanding. Some listed properties were unknown in 1789; we left out other properties discovered over time. We use valence, the most common number of chemical bonds an atom can form and a term known to Mendeleev in 1869, instead of valence electrons, the number of electrons in the outermost electron shell of an atom, a concept proposed by chemist Gilbert Lewis in the early 20th century. Scientists understood valence before they understood reactivity, which requires understanding the underlying structure of atoms, including the concept of valence electrons. Similarly, we use atomic weight instead of atomic mass in accord with the terminology used by Mendeleev. This activity is not intended to generate the modern periodic table but to use a historical approach with information modified for simplicity. October 2015 45 FI G U R E 3 Connections to nature of science. Element card samples in two sizes. Scientific Knowledge Is Open to Revision in Light of New Evidence Over time, scientists have modified and reinterpreted the periodic table as new information is discovered; students model this progression. JOANNA PHILIPPOFF Scientific Knowledge Is Based on Empirical Evidence Students look for patterns and develop explanations as they develop a series of organizational models reflecting a historical progression of empirical evidence. The chemical solitaire activity This activity can be used in any class that covers introductory chemical concepts. We implemented it in two ninth-grade marine science classes as well as a mixed-grade science elective course in a public charter laboratory school with a student body that reflects the state’s diversity. In the ninth-grade classes, the activity took two 45-minute periods during the first week of a chemistry unit. On the first day, students developed their own organization scheme for sequential groups of elements. On the second day students discussed the activity. Before the activity, the element cards are printed, cut, and placed in three envelopes labeled Set A, Set B, and Set C, respectively. The lanthanide and actinide series are excluded to limit the number of elements students have to organize. You can modify the cards depending on your goals. For example, you could include additional chemical or physical properties, such as boiling and melting points, or, to simplify the activity, you could remove the transition metals. Also, consider the area your students will have to work with; for smaller areas, we recommend reducing the size of the cards. To introduce the activity, we ask students to define or give examples of elements, which exposes their prior knowledge and conceptions. For example, some students might list fire, water, wind, and earth as “elements,” which is how Plato and other classical Greek philosophers originally classified matter. Rather than share the modern definition, we told students they would explore this concept throughout the unit, and they didn’t have to understand all of the properties listed on the element cards at first. 46 The Science Teacher Science Is a Human Endeavor Students apply creativity to solving a problem and recognize how the work of multiple scientists contributed to our modern understanding of the periodic table. Connections to Engineering, Technology, and Applications of Science Element classification systems changed over time as improvements in technology allowed for a deeper understanding of atomic structure. We framed the activity—sorting sets of element cards using students’ own system of organization—as an exploration of science, history, and modeling. This activity models the approach and struggles of historical scientists: Students will sequentially “discover” new elements. As they receive new information, they will have to incorporate it into their existing organizational framework. Students are expected to share not only their final model but also the reasoning behind their scheme. Students are arranged into groups of three to five and given approximately 10 minutes with card Set A. We ask students to “develop a system of organization for elements based on their physical properties.” Because this Set A includes elements from across the periodic table, it is difficult for some students to find trends. This mimics the historical progression; more elements needed to be discovered before clear patterns emerged. Next, we give students 10 minutes with card Set B and then 5 minutes with Set C (Figure 4). As students receive new information, we encourage them to modify their model, reflect on the reasons for their organization, and record their thought Chemical Solitaire processes. This enhances student learning and comprehension of complex concepts such as the nature of science (Hattie 2009; Seraphin et al. 2012). Questions we ask during the activity include: ◆◆ ◆◆ ◆◆ ◆◆ F IG UR E 4 Students organizing element cards (A). In this group’s model, students organized the elements into non-connected clusters based on state and reactivity (B). What information are you using to decide how to arrange the elements? Why did you group these elements together? A Why do you think this/these cards do not seem to “fit”? How can you make connections between elements or groups of elements? JOANNA PHILIPPOFF It’s critical for students to build and revise at least three different models of periodic arrangements. Students come up with a model based on limited data and modify their ideas as new information comes to light. This process emulates how, as technology improves and new evidence is uncovered, models, such as classification systems, change over time. By evaluating and refining their models, students develop an underB standing of how models have predictive and explanatory power. By comparing their final organization to the modern periodic table, your students can determine if they predicted the discovery of these elements. After receiving card Set C, students finalize their organizational model. Then they do a gallery walk to share their products and reasoning. Pictures of student work are useful to reference when discussing the activity and for assessment purposes. At this point, we share images of the historical progression of the periodic table (e.g., Figure 5, p. 48) and alternative models that emphasize properties of the elements that are not as apparent in traditional periodic tables (e.g., Figure 6, p. 48). Sharing these models supports creative student organizational strategies that are different from the modern periodic table. There are many “right” answers! As students organized their results, guiding questions include: any time during the activity? If so, explain what you started doing and what you changed. ◆◆ ◆◆ ◆◆ ◆◆ How did your group organize the elements? Explain your process of organization. Did your group change your organization strategy at ◆◆ After everyone shared in class, did you want to change how you organized the elements? If yes, explain how. If not, explain why you think your group’s strategy was “best.” Compare your organization to the modern periodic table; comment on how they are similar and different. How did this activity mimic what scientists have done in the past, and what they do today? October 2015 47 FI G U R E 5 F IGUR E 6 Lavoisier’s “Table of Simple Substances.” An example of an alternative periodic table. ALMAAK Paul Giguère’s 3-D, flower-like periodic table consisting of four connected loops (1966). AMITCHELL125 Outcomes Students also complete these questions individually for homework as a written formal assignment. Students are assessed based on the richness of their explanations of their groups’ reasoning and thought processes. The teacher uses these assessments to help tailor subsequent lessons. This activity serves as the foundation for understanding patterns in the periodic table, including the importance of valence electrons in chemical reactivity and bond formation. After further learning, students can apply their knowledge of the periodic table by completing this activity again as a summative assessment. 48 The Science Teacher In our classes, students primarily organized the elements based on weight or state of matter and secondarily grouped them by valence or reactivity. In the mixed-grade class, upper-level students (taking physics or chemistry) prioritized valence and reactivity. For example, one group focused first on valence, separating Set A cards into groups. With the addition of card Set B, they further split the elements into piles based on reactivity; elements with no listed reactivity were sorted by valence. Lastly, with card Set C, they rearranged the elements into groups based on atomic mass. All students reported that the activity increased their understanding of how elements are organized, their interest in the periodic table, and their understanding of the nature of science (Figure 7, p. 50). Students said they enjoyed working with group members, “actually physically sorting out the elements,” being creative in their organization methods, and seeing how different groups organized the elements. In written reflections, some students described how they did not want to change their first level of categorization, even after being exposed to other groups’ models. Rather than reexamining their organization strategies to create new models, the new sets of cards and their peer observations encouraged them to further divide rather than link the elements. Chemical Solitaire Connecting to the Next Generation Science Standards (NGSS Lead States 2013). The materials/lessons/activities outlined in this article are just one step toward reaching the performance expectation listed below. Standards HS-PS1 Matter and Its Interactions Performance Expectation HS-PS1-1. Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms. Dimension Name and NGSS code/citation Science and Engineering Developing and Using Models Practices • Use a model to predict the relationships between systems or between components of a system. (HS-PS1-1) Obtaining, Evaluating, and Communicating Information • Communicate scientific and technical information (e.g., about the process of development and the design and performance of a proposed process or system) in multiple formats Specific Connections to Classroom Activity Students develop and revise models of how the elements are organized based on evidence and compare their models to accepted scientific models. Students gather information from the element cards, communicate their organization scheme and reasoning, and evaluate different organization strategies. Disciplinary Core Idea PS1.A Structure and Properties of Matter • The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states. Students classify elements based on their chemical and physical properties. Crosscutting Concept Patterns • Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena. (HS-PS1-1) Students identify patterns in element properties and use these patterns as evidence to support their organizational scheme. Common Core State Standards (NGAC and CCSSO 2010) • ELA-LITERACY.RST.9-10.4. Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9–10 texts and topics. • ELA-LITERACY.RST.11-12.5. Analyze how the text structures information or ideas into categories or hierarchies, demonstrating understanding of the information or ideas. • CCSS.MATH.PRACTICE.MP3. Construct viable arguments and critique the reasoning of others. • CCSS.MATH.PRACTICE.MP7. Look for and make use of structure. C3 Framework For Social Studies State Standards • D2.His.9.9-12. Analyze the relationship between historical sources and the secondary interpretations made from them. October 2015 49 FI G U R E 7 Results of ninth-grade student feedback survey (N = 47). Each question was on a scale of 1–5, with 1 = “the activity did not increase my understanding/interest” to 5 = “the activity greatly increased my understanding/interest.” Construct Prompt Content Understanding To what extent do you think doing this activity increased your understanding of how elements are organized? 3.34 History of Science To what extent do you think learning about the history of the periodic table increased your interest in the periodic table? 3.17 0.92 “I thought this activity was really good because we got to see how many more elements were added throughout time.” Nature of Science To what extent do you think organizing the elements increased your understanding of how scientific knowledge builds and changes over time? 3.51 0.80 “I liked how we only knew limited information first, then we realized how different what we thought before was after.” To what extent do you think organizing the elements increased your own understanding of the importance of imagination and creativity in science? 3.49 Periodic Table Trends Scientific Knowledge Is Open to Revision in Light of New Evidence Nature of Science Science Is a Human Endeavor Mean Students were more attached to their original models than we anticipated, perhaps because they didn’t want to think of their original models as “incorrect.” This reflects the challenges in teaching the nature of science through inquiry. Besides discussing these issues with students during and after the activity and increasing the time students spend with Set A, having students share their reasoning through their first model may help emphasize the process rather than the product. The teacher in our example—one of the authors—was implementing this activity for the first time. She noted: “The lesson was very engaging for the students, even with very lit- 50 The Science Teacher Standard Deviation 0.87 Sample Student Comments “I liked organizing the elements, and finding new ways to organize them was really helpful to understanding the periodic table better.” “I liked how we needed to find different ways to organize the elements and also find out what the elements have in common with each other.” “I liked how we were able to work together and that we were able to see the development of scientific findings.” 0.93 “The best thing about this activity was getting to organize the elements in ways we created ourselves because that is how we understood them.” tle prior introduction to the topic. Most students were actively engaged in the post-activity discussion. Students seemed to like the idea that they had done an activity that mimicked what scientists did in the past in order to study and organize the elements.” Conclusion Emulating the scientific process using historical examples can develop students’ understanding of the nature of science. They gain an appreciation Chemical Solitaire that scientific knowledge is based on empirical evidence, is open to revision in the light of new evidence, and is a human endeavor. Experiencing the periodic table through a historical lens enhances student interest, understanding, and engagement in difficult content and helps them connect to the rich history of scientific human ingenuity. ■ Joanna Philippoff (philippo@hawaii.edu) is a program manager and Kanesa Duncan Seraphin (kanesa@hawaii.edu) is an associate professor at the University of Hawaii at Manoa; Jennifer Seki (jennifer_seki@universitylaboratoryschool.org) is a teacher at the University Laboratory School in Honolulu; and Lauren Kaupp (lauren_kaupp/cib/hidoe@notes.k12.hi.us) is an educational specialist for science and STEM at the State of Hawaii Department of Education in Honolulu. On the web Downloadable elements cards; timeline of events in the construction of the modern periodic table: www.nsta.org/highschool/con nections.aspx References Hattie, J. 2009. Visible learning: A synthesis of over 800 meta-analyses relating to achievement (pp. 1–378). New York, NY: Routledge. Lederman, N.G. 2007. Nature of science: Past, present, and future. In Handbook of research on science education, ed. S.K. Abell and N.G. Lederman, 831–879. Mahwah, NJ: Lawrence Erlbaum. National Governors Association Center for Best Practices and Council of Chief State School Officers (NGAC and CCSSO). 2010. Common core state standards. Washington, DC: NGAC and CCSSO. NGSS Lead States. 2013. Next Generation Science Standards: For states, by states. Washington, DC: National Academies Press. Seraphin, K.D., J. Philippoff, L. Kaupp, M.H. Lurie, D. Lin, E. Baumgartner, and F.M. Pottenger. 2015. Exploring our fluid Earth. University of Hawaii. www.exploringourfluidearth.org. Seraphin, K.D., J. Philippoff, L. Kaupp, and L.M. Vallin. 2012. Metacognition as means to increase the effectiveness of inquirybased science education. Science Education International 23 (4): 366–382. October 2015 51 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Taber / TUSED / 8(1) 2011 3 Journal of TURKISH SCIENCE EDUCATION Volume 8, Issue 1, March 2011 TÜRK FEN EĞİTİMİ DERGİSİ Yıl 8, Sayı 1, Mart 2011 http://www.tused.org Models, Molecules and Misconceptions: A Commentary on “Secondary School Students’ Misconceptions of Covalent Bonding” Keith S. TABER1 1 Senior Lecturer in Science Education, University of Cambridge, Faculty of Education, United Kingdom Received: 29.12.2010 Revised: 31.01.2011 Accepted: 04.02.2011 The original language of the article is English (v.8, n.1, March 2011, pp.3-18) ABSTRACT Learners often find studying secondary school chemistry challenging, and commonly develop alternative understandings of the subject, variously labelled by researchers as misconceptions, alternative conceptions, conceptual frameworks, and so forth. An example of enquiry into this area is provided by Ünal, Coştu & Ayas in a recent paper in the Journal of Turkish Science Education. Ünal and colleagues explored student misconceptions relating to the fundamental concept of covalent bonding, and classified student responses in their study according to both the soundness of student comments, and the presence of misconceptions. Research of this kind is complicated by both the nature of the simplifications used to teach chemistry at this level (which complicate decisions about what is taken to constitute ‘sound’ student knowledge), and the difficulty of appreciating the nature of student ‘misconceptions’, which may actually vary considerably in their significance for progression in student learning. This commentary offers a reconsideration of Ünal and colleagues’ results in the light of previous published research into student understanding of chemical bonding, which suggests that Turkish Secondary School students’ thinking about Bonding seems to reflect a previously reported alternative conceptual framework. Keywords: Student Misconceptions; Understanding Chemical Bonding; Pedagogical Learning Impediments; The Octet Alternative Conceptual Framework; The Bonding Dichotomy Teaching Model. INTRODUCTION Ünal, Coştu and Ayas (2010), have recently published a very interesting study in Journal of Turkish Science Education on ‘Secondary school students’ misconceptions of Correspondence Author email: kst24@cam.ac.uk © ISSN:1304-6020 Taber / TUSED / 8(1) 2011 4 covalent bonding’. This study deserves note, because bonding is a central topic in chemistry, and one that is commonly reported to be challenging for learners (Hofstein, Levy Nahum, Mamlok-Naaman, & Taber, 2010; Özmen, 2004; Taber & Coll, 2002; Ünal, Çalık, Ayas, & Coll, 2006). Students have been found to develop alternative conceptions in this topic in a range of national contexts (Coll & Treagust, 2003; Griffiths & Preston, 1992; Nicoll, 2001; Peterson, Treagust, & Garnett, 1986; Taber, 1998), including Turkey (Nakiboğlu, Tsaparlis, & Taber, 2009). In their study, Ünal et al. (2010) report examples of student comments made in response to their research probes, and characterise students’ responses according to the soundness of subject knowledge demonstrated, as well as whether student comments indicated misconceptions. In this commentary, I set out to reconsider the analysis presented in this recent research report (Ünal et al., 2010), and argue that whilst the data presented are of great interest, the paper’s findings must be seen to be of limited validity because the conceptual and analytical framework adopted in the paper does not pay sufficient attention to (a) the nature of chemical knowledge and its representation in teaching; (b) the substantial differences between different types of ‘misconception’. My purpose here is not to criticise these authors, who have produced a paper of considerable interest, but rather to offer a critique that might be helpful for researchers, and inform further research of this general type in the Turkish context and elsewhere. Scientific models and curriculum models Part of the challenge for students learning about chemical bonding derives from its abstract nature. Chemical bonds are components of the submicroscopic models used by chemists as the main theoretical basis for explanations in the subject. For many chemists, the molecules, ions, electrons and other such ‘quanticles’ (quanta of matter at such a small scale that they exhibit wave and particle behaviour) of the submicroscopic world as so familiar they seem as real as the beakers, flasks and test-tubes used in the laboratory. For students, the submicroscopic world is not only unfamiliar, but also largely counterintuitive – matter seems continuous, and is not obviously made of the tiny fuzzy balls of electrical fields presented by modern science. Molecules, ions, atoms and the bonds that hold them together are not real objects that can acts as referents in the observable world, but conjectured theoretical objects that populate chemists’ explanatory schemes. This is not to suggest that these entities are ‘only imaginary’ and have no real basis; but rather to stress that it is important to recognise that what chemists (including chemistry teachers) refer to when using terms such as ‘molecule’ or ‘bond’ are actually models intended to represent aspects of world as uncovered in scientific investigations (Taber, 2010). This becomes clear if one asks what an atom is actually like: atoms have been described by a sequence of different models historically, all of which offer a useful, but ultimately limited, description of atoms (Justi & Gilbert, 2000; Taber, 2003). Representing scientific ideas in the curriculum Research to assess school students’ understanding of scientific concepts is complicated because many scientific ideas and models are too sophisticated to be taught in schools. So the school curriculum includes representations of science (Millar, 1989): that is, curriculum models of the scientific ideas (Gilbert, Osborne, & Fensham, 1982). When well designed, such curriculum models catch something of the essence of the scientific ideas, and provide learners with a suitable basis for progression in learning: that is, curriculum models are simplifications suitable for developing more sophisticated understanding (Taber, 2000b). Taber / TUSED / 8(1) 2011 5 Although simplification is necessary, the simplifications we teach should be designed to be ‘intellectually honest’ (Bruner, 1960). In principle, this is something scientists should appreciate, as many of the models used in science are themselves known to be simplifications, but are still of great value within their range of application. Indeed, it has been argued that the models of molecules and atoms and chemical bonds that are widely used within the chemical community for most purposes, are actually a good deal less sophisticated than the currently most precise available models of molecular structure (Sánchez Gómez & Martín, 2003). So thinking of molecules as atoms linked with bonds comprised of pairs of electrons is some way from the most advanced current scientific understanding, but remains a very useful way of thinking about matter at the submicroscopic scale. Foundations for further learning versus pedagogical learning impediments Whilst well-designed curriculum models will provide the basis for progression in learning, poorly designed curriculum models have the potential to actually impede further learning by encouraging ways of thinking inconsistent with scientific models (Taber, 2001). Even if the official curriculum models are sound, teachers develop their own personal teaching models, often based on metaphors and analogies designed to link to students’ familiar experiences, to help communicate these ideas to pupils, and these teaching models may have elements that are unhelpful in the context of the scientific model (Nakiboglu & Taber, 2010). Well chosen analogies may be a useful tool in teaching and learning, but even these are not always understood as intended by students (Ünal et al., 2006). Learner’s ‘misconceptions’ can derive from a variety of different sources (Taber, 2009), but in chemistry there are good grounds to think that many derive from aspects of the way the subject is taught, acting as pedagogic learning impediments (Taber, 2009). That is, some of the teaching models used to introduce pupils to scientific ideas may actually work against later progression in the subject. The bonding typology as an example of a learning impediment This certainly seems to be the case in the teaching of chemical bonding. For example in secondary chemistry teaching, a common teaching model is to consider chemical bonding in compounds as forming a dichotomy, with two main types of bond – covalent and ionic (as shown in figure 1), and examples of bonds assigned to one category or the other. Covalent bonds are said to form between non-metals; and ionic bonds between a metal and a non-metal. Students tend to readily adopt this dichotomy. Figure 1. A teaching model – the bonding dichotomy However, progression in learning requires students to shift from thinking of elements in terms of the categories of metal and non-metal to considering electronegativity; and so from considering bonds in compounds as being either ionic or covalent to instead having Taber / TUSED / 8(1) 2011 6 different degrees of polarity, depending upon the pattern of electron density in the bond. Bonding in compounds is then understood as forming a continuum, for which the ionic and covalent cases represent poles (see figure 2). Indeed these may be seen as ‘ideal cases’ with no bonds perfectly matching the ionic pole of the continuum. In effect nearly all bonds in compounds are understood as being polar, to a greater or lesser degree. Figure 2. Bonding in compounds lies on a continuum, not a dichotomy. This raises the question of whether a teaching model of there being two types of bond in compounds (figure 1) should be considered a useful simplification. At first sight it seems a sensible way of introducing bond types, which could provide the conceptual basis of progression in learning to a more sophisticated understanding (figure 2). However research suggests that learning about bonding as a dichotomy can act as a learning impediment, interfering with later learning about bonding as a continuum (Taber, 1998). Students who learnt about bonding as a dichotomy tend to have difficulty shifting to thinking in terms of a continuum. They tend not to appreciate that most bonds are polar, and that there are many graduations of polar bonding between the ionic and covalent extremes, and instead to simply see polar bonds as somewhat distorted covalent bonds (see figure 3). Figure 3. Common student understanding of polar bonds as a type of covalent bond This type of misunderstanding of polar bonding was illustrated by students reported in Ünal et al’s paper (Ünal et al., 2010). To summarise the argument here, then: · Scientific models are often simplifications · Scientific ideas are simplified further in designing target curriculum knowledge · Teachers find ways to communicate curriculum knowledge using models, analogies, metaphors, that often simplify (or distort) ideas further · Some simplifications can provide a good basis for building new knowledge, but others may impede understanding and misdirect learning. Taber / TUSED / 8(1) 2011 7 The nature of student misconceptions There is an extensive literature in science education on student misconceptions (Duit, 2009). Moreover, there has been a long and vigorous debate about the nature of learners’ ideas in science, and whether they are best described as alternative conceptions, conceptual frameworks, intuitive theories, mini-theories etc (Claxton, 1993; Driver & Erickson, 1983; Gilbert & Watts, 1983; Solomon, 1993). For example, it has been suggested that ‘misconception’ implies a misunderstanding of canonical knowledge (such as misunderstanding teaching), whereas ‘alternative conception’ would also include notions developed spontaneously, for example intuitive notions acquired from direct experience of the world (diSessa, 1993). The term misconception also seems inappropriate for those situations where an individual acquires technically incorrect ideas from another – for example where teachers themselves have flawed subject knowledge and present incorrect ideas in class (Taber & Tan, 2011). In this situation, the learners do not ‘misconceive’ what has been taught, but rather may correctly understand the alternative conceptions presented. The term ‘alternative conception’ is also sometimes considered to better fit with the constructivist perspective (Taber, 2009), that considers learning as necessarily an active process of personal knowledge construction within each individual. For brevity, here I will refer to ‘misconceptions’ - a term that has commonly been used to discuss these ideas with teachers, for example in chemistry (Taber, 2002). This debate has considered the nature, and educational significance, of misconceptions, and different positions have been taken about their likely consequences (Gilbert et al., 1982). A recent extensive review of the topic (Taber, 2009) concluded that the evidence suggests that student misconceptions vary along a range of dimensions, with some – but not all – being highly influential on the course of likely conceptual change and so progression in learning. This is important for researchers such as Ünal, Coştu & Ayas, as simply identifying comments students make which are at odds with target knowledge, and labelling them all as ‘misconceptions’ – as in Ünal et al. (2010) – offers little insight into the implications of research for teaching. An alternative conceptual framework in chemistry education Some alternative conceptions elicited in research with learners seem to be especially significant for student learning. A good example is the common way of thinking about force and motion that sees a force as bringing about motion, rather than (as in the scientific understanding) an acceleration, and so a change in motion (Gilbert & Zylbersztajn, 1985). This ‘impetus’ framework, associating constant motion with a force, is found among the vast majority of learners (Watts & Zylbersztajn, 1981), and is known to be tenacious; resisting correction by teaching (McCloskey, 1983). In chemistry education, it has been argued that students commonly adopt an equally tenacious alternative conception relating to the behaviour of matter at the submicroscopic level. Students commonly adopt a belief that atoms want to, and act to, fill their shells (or obtain octets of electrons). This simple idea acts as the basis for an extensive (alternative) conceptual framework used to explain why bonds form, why reactions take place, the patterns found in ionisation energies and so forth (Taber, 1998). Students using this principle have considerable success in explaining some aspects of chemistry. They will understand that atoms can obtain full shells by sharing electrons, or by donating them from one atom to another. The availability of these two ‘mechanisms’ for forming bonds, supports the students in understanding that there are two main categories of bond – covalent and ionic (cf. figure 1). Unfortunately, such ideas are unhelpful when students are asked to learn about polar bonding, Taber / TUSED / 8(1) 2011 8 electron-deficient compounds, compounds where atoms ‘expand their octet’, hydrogen bonding etc. Thinking of bonding in ‘octet’ terms, acts as an impediment to progression in learning. In chemistry, there are a range of different types of bonding which are important in understanding structures, and all can be understood to a first approximation in terms of electrical interactions – whereas thinking of bonding in terms of atoms filling their shells, tend to lead to student excluding anything which cannot be understood in ‘octet’ terms as bonding. When thinking about covalent bonding, students tend to adopt the ‘sharing’ metaphor, but unfortunately understand this in anthropomorphic terms – seeing the sharing, not the electrical interaction, as the bond (Taber, 1998). In the ionic case, students tend to see bonding in terms of electron transfer between atoms – something which is both chemically unrealistic, and leads to misunderstanding the nature of the ionic lattice (Taber, 1994, 1998). The significance of these ‘misconceptions’ can be seen by how pupils will commonly explain chemical reactions as occurring to allow atoms to fill their shells – although almost inevitably the reactants already comprise of species with stable configurations (Taber, 1998). Despite often having themselves made NaCl by neutralisation of an acid (containing Cl- ions) and an alkali (containing Na+ ions), students will claim that the formation of NaCl involves electron transfer. Similarly, students will explain double decomposition reactions in terms of electron transfer, despite the ionic solid being formed by ions already present in the solution (Taber, 2002). In the covalent case, advanced students asked to explain why H2 reacts with F2 commonly ‘explain’ this in terms of the hydrogen and fluorine atoms trying to fill their shells (Taber, 2002), even after being taught about the principles of energetics, and bond energies. The octet conceptual framework is not only widespread, but highly influential in student thinking, impeding the progression of learning of the scientific models. Ünal, Coştu & Ayas’ data on secondary school students’ misconceptions of covalent bonding If these ideas are applied to the results reported by Ünal et al. (2010), it becomes clear that these researchers have collected some very interesting data, that are very informative in the Turkish context; but there is a strong case for considering the approach to the analysis to be sub-optimal. Students written responses on covalent and ionic bonding The first of several questions requiring written responses discussed by Ünal et al. (2010, p. 7) “investigates whether or not students could predict what type of atoms form covalent bonding. It also investigates whether or not students could determine the type of chemical bonding which is formed between the atoms in the given compounds”. The authors classify student responses here into four categories – (i) sound understanding; (ii) partial understanding; (iii) partial understanding with specific misconception; (iv) specific misconception – and report the proportion of responses in each category. Examples of students’ responses are provided to illustrate the analysis, and this allows the reader to consider how the classification was made. Two examples of responses from each category are reproduced here in Table 1. Taber / TUSED / 8(1) 2011 9 Table 1. Examples of students’ written responses to a question about covalent bonds–from Ünal et al. (2010). Statement Student response 1 HCl : It is covalent bond, because it is formed between two nonmetal atoms. They share their electrons. MgCl2 : It is ionic bond, because it is formed between a metal and a nonmetal atom. Bonding is formed by means of the attraction between oppositely charged ions. MgCl2 : Mg: 12, Cl: 17, Mg+2 Cl-1. It is ionic bonding. Magnesium and chloride ions bond with each other by means of their opposite electric charges. NH3 : N: 7, N: 1s2 2s2 2p3 Nitrogen share their single electrons with three hydrogen atoms, so that they have full outer shell. Therefore, covalent bonding is formed between nitrogen and hydrogen atoms. 2 3 4 Classification by Ünal et al. sound understanding Note Uses anthropomorphic ‘sharing’ metaphor sound understanding Explains in electrical terms, but focuses on atoms partial understanding Similar to item 2 partial understanding Uses anthropomorphic ‘sharing’ metaphor partial understanding with specific misconception Wrong label for bond type. Demonstrates electron transfer alternative conception; anthropomorphic language Demonstrates electron transfer alternative conception ” 5 6 7 8 HCl: It is ionic bonding. While the chlorine atom wants to take an electron to have full outer shell, the hydrogen atom wants to give. So, one electron is transferred from the hydrogen to the chlorine atom. MgCl2: It is ionic bonding. While magnesium atom is metal, chlorine atom is nonmetal. So, magnesium atom transfers one electron to each chlorine atom. HCl: It is ionic bonding, because both atoms are nonmetal. MgCl2 : It is covalent bonding, because magnesium is metal, chlorine is nonmetal. partial understanding with specific misconception specific misconception specific misconception Wrong label for bond type Wrong label for bond type Consideration of the issues raised earlier in this paper suggests that a simple four-way classification of the data as used by Ünal and colleagues ignores some key points. A significant methodological limitation of this type of data is that of what is not included: students’ responses reflect what the student brought to mind and thought important to include. For example, consider statements 2 and 3 in Table 1. Both responses identify the type of bond in magnesium chloride as ionic; and both explain that this type of bonding has an electrical basis (“attraction between oppositely charged ions”; “bond with each other by means of their opposite electric charges”). Presumably statement 3 is considered to only demonstrate ‘partial understanding’, rather than the ‘sound understanding’ of statement 2, because the student has not mentioned that this compound is formed between a metal and a non-metal. If Ünal et al. consider this to be an essential part of understanding the nature of covalent bonding, then it makes sense that they judge this answer to only provide evidence of partial understanding. The knowledge may have been available to the student, but if so, it was not elicited. This is an inherent problem with collecting data in written form, and Ünal et al. (2010) are to congratulated on including interviewing to complement their written probe. However, of more interest perhaps is a comparison between these two responses and statement 1 in the table. Where statement 3 (considered ‘partial understanding’) explains the Taber / TUSED / 8(1) 2011 10 ionic bond in terms of electrical interactions, statement 1 (considered to show ‘sound understanding’) explains the covalent bond in terms of the sharing metaphor, and does not make any reference to the physical basis for the bond. From the perspective of understanding that will support progression in learning about scientific models, statement 3 (‘partial understanding’) seems to offer a better basis for future learning than statement 1 (‘sound understanding’). Statement 4 also uses the sharing metaphor, and seems to imply that atoms share electrons to obtain full outer electron shells – language that could imply this student holds the octet alternative conceptual framework discussed above. In describing the responses to a later question about bonding in the water molecule (item 3), Ünal et al. give as an example of a response indicating sound understanding a student answer which includes the statement that “a covalent bond is the attraction of the bonding electrons by the nuclei of both hydrogen and oxygen atom” (p.11), yet in the earlier question seem to consider a reference to the ‘sharing’ of electrons sufficient for a sound understanding. It is also of interest to see how these authors identify misconceptions within the student data. Statements 7 and 8 are both presented as examples of responses labelled as showing a ‘specific misconception’. Clearly both answers are wrong. The students respond with the wrong names for the different types of bonding. However, whether that is sufficient evidence of a misconception is not clear. Students may have made a simple mistake in writing their answers, or may have simply not remembered which name went with which type of bonding, and so guessed. In neither situation should this be considered a misconception (Gilbert & Watts, 1983; Taber, 2009), rather just a mistake. We all get things wrong sometimes, without this meaning we have significant alternative understandings of the world. It is also possible, as Ünal et al. acknowledge (p.22), that these responses may result when student has genuinely learnt the labels the wrong way round, and so this would reflect a genuine flaw in conceptual learning. But even in this case, it is questionable whether this justifies the incorrect learning being termed a misconception. The bonding types might be well understood, but the names mis-learnt. If all these types of errors are considered misconceptions, then the term loses its significance. It is interesting in this context to compare statements 7 and 8 in Table 1, with statements 5 and 6, which are each considered by Ünal and colleagues to demonstrate ‘partial understanding with specific misconception’. Statement 6 recognises the presence of ionic bonding, but shows little evidence of the student understanding this bond type, explaining the bond in terms of electron transfer. Simply knowing the name of the bond type would normally be considered to demonstrate recall, not understanding (Anderson & Krathwohl, 2001; Bloom, 1968). Just as getting the name of the bond type wrong (statements 7, 8) might be considered insufficient evidence of a misconception; getting it right seems insufficient grounds for recognising understanding. Statement 5 is of particular interest, as here the student: (a) misnames the bond-type; (b) uses anthropomorphic language to imply that atoms seek full outer shells; (c) considered the bond in terms of electron transfer between atoms. So here there is an error (a), and evidence of two alterative conceptions (b and c) consistent with the student holding the octet alternative conceptual framework. Ünal et al. classify this response as demonstrating ‘partial understanding’ (with specific misconception), presumably because the student appreciates that compounds between metals and non-metals tend to form ionic bonds. The student applies a simple rule, but seriously misunderstands the nature of the bond. Taber / TUSED / 8(1) 2011 11 Treatment of polar bonding Ünal et al. turn next (p.9) to consider a question that “investigates students’ ideas about the position of bonding electrons between covalently bonded atoms…to determine to what extent students could predict the position of bonding electrons between two nonmetal atoms whose electronegativities are different from each other”. Ünal et al. ask students to “determine the positions of bonding electrons between the atoms in the given compounds” (p.9). As explained above, bonding in compounds tends to be polar, to a greater or lesser extent. No ‘pure’ ionic compounds are known. Salts are generally considered ionic, although the ions in salts are ‘polarised’ to some extent even when they approximate the ionic model. That is, it is possible to model the bonding in salts by considering them to be ionic, to a first approximation, and then considering how the cationic charges would distort the electron density around the anions. This is purely a way of thinking about the bond, just as it is possible to model the bond in HCl or H2O by considering how a purely covalent bond would be distorted by the different effects of the core charges at either end of the bond. However, if bonds are understood in terms of minimal energy configuration of the charges involved (e.g. as solutions to the Schrödinger equation), which are simply the result of the forces acting, then there is no reason to begin from the ideal ionic or covalent bond models. Pure covalent bonds are also rare in compounds, only found where two elements have similar electronegativity (SiH4) or in some cases where there are bonds between atoms of the same element (the C-C bonds in ethane, benzene or cyclohexane for example, but not the C-C bonds in ethanol or ethanoic acid). Interestingly, Ünal et al’s paper, in the question considered above, HCl, NH3 and CO2 were used as examples of covalently bound molecules. Two of these three examples have bonds that are polar enough to allow hydrogen bonding to form between molecules. Technically, all those compounds have polar bonds rather than covalent bonds, and it is difficult to find a compound with a simple molecule that is familiar from school chemistry that has non-polar bonds. In their question about the position of bonding electrons in compounds Ünal et al. use the examples of HF; H2 ; H2S and CH4 and explain that “the position of bonding electrons in H2 compound [sic] were different from those in the other molecules because of the nonpolar covalent bonding formed between two hydrogen atoms” – although H2 is of course an element and not a compound. In classifying student responses, Ünal et al. report that “students who stated that bonding electrons were shared equally in all covalent molecules and placed the bonding electrons equidistantly to the bonded atoms in their drawings for all of the given molecules were classified in the category of specific misconception” (p.10). This is based upon there being two types of covalent bonds, those with equal ‘sharing’ of the bonding electron pair, and those where “bonding electrons were not shared equally” (p.9). In other words, in determining which answers should be considered sound, and which indicate misconceptions, Ünal et al. adopt as target knowledge the notion that polar bonds are a type of covalent bond (as in Figure 3), rather than something intermediate between the ionic and covalent bond models (as in Figure 2). Misunderstanding hydrogen bonding Another interesting result reported by Ünal et al. was that some students misunderstood the nature of hydrogen bonding. For example, in item 3 of the written probe, where student were asked about the bonding in water, one respondent wrote: “hydrogen bonding is formed between oxygen and hydrogen atoms in a water molecule. They bond with each other by sharing of their single electrons” (p.11). Taber / TUSED / 8(1) 2011 12 This seems to be an example of an alternative conception that has been reported before, associated with the octet alternative conceptual framework (Taber, 1998). Where pupils think of bonding as the means by which atoms fill their shells, then such interactions as hydrogen bonding, solvation interactions, van der Waals’ forces and so forth do not fit the student’s criterion for a chemical bond, as they do not allow atoms to fill their valence electron shells. When students hear teachers referring to a hydrogen bond, it seems that students commonly assume this is meant to refer to a covalent or polar bond to hydrogen, as the interaction between a ∂+ hydrogen atom and a ∂- atom on another molecule does not fit their notion of a bond in terms of atoms trying to fill their shells. Exploring student thinking in interviews It is widely accepted that written probes are a crude means of investigating student thinking. They can be suitable for testing the general level of support for specific misconceptions already identified in a population (Taber, 2000a), but it has long been accepted among researchers in science education that more-in-depth approaches are needed to explore student thinking (Bell, 1995; Gilbert, Watts, & Osborne, 1985; White, 1985). This reflects general understanding of the difference between ‘exploratory’ and ‘confirmatory’ approaches to research – that qualitative, in-depth approaches to exploring specific learners and contexts are needed to support the identification of suitable items that are valid for use in survey instruments (Taber, 2007). Ünal et al. used interviews to complement their written probe, and the potential of interviews to investigate student thinking is illustrated in the extract from transcripts presented in the paper. For example, when student S3 was asked about ‘types’ of covalent bonding s/he initially responded in terms of there being a difference between nonpolar covalent bonds, where “two atoms of the same element bond to each other” and polar ‘covalent’ bonding where “different atoms bond to each other” (p.18). Had that been a written response it could have seemed to indicate that this student had simply learnt rote definitions, without any deeper understanding. However follow-up questions revealed that this student was able to go on to explain that in polar bonds “the bonding electrons are closer to one of the bonded atoms than the other”, and that this was because “one of the bonded atoms which has greater electronegativity than the other will attract the bonding electrons more powerfully than the other atom” (p.18). Evidence for Turkish secondary students’ thinking reflecting the octet conceptual framework This potential for using follow-up questions allowed Ünal et al. to provide more convincing evidence for why students should be considered to have ‘sound’ or ‘partial’ understanding in the interviews, where in the written responses absence of evidence cannot be considered strong grounds for assuming absence of understanding. In their paper, Ünal et al. do not review the previous research suggesting that English students commonly conceptualised covalent bonding in terms of the Octet alternative conceptual framework (Taber, 1998). However, the interview data they present offers a range of examples of student comments that would suggest Turkish students think about bonding in very similar terms to that found among English students in the earlier study. Some examples are presented in Table 2. Taber / TUSED / 8(1) 2011 13 Table 2. Statements from data presented in Ünal et al. (2010) reflecting the Octet Alternative Conceptual Framework Aspect of the Octet Framework Examples of statements from Ünal et al.’s interviews Bonding seen as driven by attainment of full outer shells/octet/noble gas configuration S3: … “nonmetal gains electrons, so that they have more stable configuration as noble gases.” S2: “ Hydrogen needs an electron to have two electrons in its outer shell. Oxygen needs two electrons to have eight electrons in its outer shell. Each hydrogen atom shares one electron with oxygen. So, all atoms have full outer shell and they bond to each other.” S4: “ Sodium atom gives an electron and chlorine atom takes this electron, because they want to have noble gas configuration. Each of them has full outer shell.” S7: “ Oxygen atom tends to take two electrons to have full outer shell, while hydrogen atom tends to take one.” S9: “ They must share their single electrons, because both of them need one electron to have full outer shell.” S10: Hydrogen and oxygen atoms... tend to gain electrons to have stable configurations. They share their single electrons, so they have full outer shell.” ‘Sharing’ metaphor seen as a sufficient description of covalent bond S2: “ Each hydrogen atom shares one electron with oxygen. So, all atoms have full outer shell and they bond to each other… I just know that they bond to each other, because they share their single electrons. Bond is... it must be shared electrons. They are also called bonding electrons. Thus, shared electrons must be bond. They hold the atoms together.” S3: “When two nonmetal atoms react with each other, they form molecules by sharing of their single electrons.” S7 “They share their electrons and form water molecules… They shared their electrons, so they bonded together.” S9: “[covalent bonding is formed between atoms] By sharing of their single electrons” “ They must share their single electrons, because both of them need one electron to have full outer shell. So, they form covalent bonding.” S10: “ They share their single electrons, so they have full outer shell. Thus, they form covalent bond…. They share their single electrons, so they have full outer shell. Thus, they form covalent bond.” Bonding described in anthropomorphic terms: what atoms ‘want’, ‘need’ S1: “they want to gain electrons to resemble stable noble gases configuration. They want to have a full outer shell… Metals want to lose electrons, while nonmetals want to gain…metals want to lose electrons, but nonmetals want to gain. If so, they are able to think and want” S4: “Sodium atom gives an electron and chlorine atom takes this electron, because they want to have noble gas configuration… Both of them meet the needs of each other” S5: “metals want to give electron while nonmetals want to take…We learned that metals wanted to lose electrons, while nonmetals wanted to gain.” Taber / TUSED / 8(1) 2011 14 Table 2. Continued... Ionic bonds identified with electron transfer S1: “the metal atom gives its electron to the nonmetal atom. They form ionic bonding.” S4: “Sodium atom gives an electron and chlorine atom takes this electron, … Therefore, they form covalent [sic] bonding… sodium gave one electron to the chlorine atom, and the chlorine atom took the electron. Both of them meet the needs of each other, so that they bonded to each other…[bonding] must be… the electron which transferred from the sodium to the chlorine atom… They bonded to each other by means of the electron that sodium gave and chlorine took… An electron is transferred from sodium atom to chlorine atom. They are hold together by this means” S5: “Metal atoms transfer some electrons to the nonmetal atoms. So, they bond to each other.” Ionic bonding considered to result in molecules or molecule-like entities S1: “ a metal and a nonmetal atom will form a molecule,” Polar bonds seen a type of covalent bond S3: “ [types of covalent bonding are] polar and nonpolar covalent bonding.” S7: “there are two types [of covalent bonding]. These are polar and nonpolar covalent bonding… There is no more difference between polar and nonpolar covalent bonding. They are covalent bonding in anyway. They differ from each other only according to being formed between different nonmetal atoms or the same nonmetal atoms” S8: “there are two types of covalent bonding. These are polar and nonpolar covalent bonding… Scientists have differentiated covalent bonding according to being formed between different nonmetal atoms or the identical ones” Hydrogen bonding is interpreted as covalent/polar bond S9: “ Hydrogen bond is formed within HCl molecules… it is both covalent bond and hydrogen bond… Because chlorine atom bond to hydrogen atom, we could say that they form hydrogen bonding as well…. it is the same with covalent bonding. It is formed between hydrogen and chlorine atom by sharing of their single electrons…There is no difference…[hydrogen bonding] is covalent bonding. But, it is also hydrogen bonding because it is formed between an atom ‘chlorine’ and hydrogen atom… Hydrogen bonding is formed within molecules comprising of one hydrogen atom with other atoms”. There is much evidence here that Turkish students adopt aspects of the Octet conceptual framework that was found to be common among English students. CONCLUSIONS Ünal et al.’s paper presents evidence from a written probe and interviews, which they use to demonstrate that Turkish secondary students show evidence of misconceptions in this key concept area of school chemistry. This is an important finding. However, it has been suggested here that Ünal and colleagues’ study has used an analytical framework that does not do justice to the complexity of the phenomena explored. Ünal et al. do not give sufficient weight to the way their judgement of what comprises sound understanding is tied to their adoption of particular teaching models. So whilst they rightly recognise that identifying the ionic bond with electron transfer reflects inadequate understanding, they appear to consider that descriptions of the covalent bond as ‘sharing’ of electrons constitutes the basis for sound understanding. Similarly, Ünal et al. adopt a dichotomous notion of chemical bonding in compounds which sees polar bonds as a sub-category of covalent bond. This teaching model has been criticised as being a poor basis for progression in learning, and clearly judgements of Taber / TUSED / 8(1) 2011 15 which pupils demonstrate sound understanding would be quite different had Ünal et al. made a different choice here. An observer (such as the author of this commentary) who disagreed with the decisions made about what constituted appropriate target knowledge for these students will not accept the findings – the claimed proportions of the sample displaying sound understanding, for example. However, despite this, Ünal et al.’s study is of value because it follows good practice in reporting research, by being open about the basis of the researchers’ decisions, and offering good examples to illustrate this from the data - which allow readers to make their own judgements. It also offers some extended extracts from interview transcripts, which reflect the kind of data that have been used productively by many other researchers to explore student thinking in depth. This data allows the researcher to move beyond the rote responses students give based on learnt definitions, to find out something about the coherence, depth and logic of student thinking (Taber, 2008). So, for example, both students S1 and S10 associate covalent bonding with sharing of electrons to allow atoms to fill shells. Yet the interactive potential of interviews allows researchers to probe further and we discover that for S1, this is the extent of understanding, based on anthropomorphic notions of atoms that act on their needs (Taber & Watts, 1996), whereas S10 is able to appreciate how the sharing metaphor stands in place of a physical explanation in terms of the electrical attractions between bonding electrons and nuclei. In their study, Ünal et al. identify apparent evidence of student misconceptions, but as they concede in the discussion section of their paper, the analytical approach they adopt does not readily distinguish between simple confusing of terms and the holding of alternative conceptions with significant potential to impede further learning (Taber, 2009). Considering that Ünal et al.’s paper only presents a selection of extracts from their interview study – intended to illustrate how they assigned students to their four categories ((i) sound understanding; (ii) partial understanding; (iii) partial understanding with specific misconception ; (iv) specific misconception) - it is intriguing that these extracts provide so much evidence of student thinking aligned with the octet alternative conceptual framework (Table 2), suggesting that in some important respects the thinking of secondary students in Turkey may be similar to what has been reported in the English study (Taber, 1998). It might be conjectured that a more detailed analysis of the full data set could offer a useful comparison with the results of the research from the English context. Ünal et al.’s study attempts to classify student understanding of a key chemical concept area, in terms of a small number of categories. In doing so it illustrates to Turkish science educators that Turkish students, as those in other countries, experience learning difficulties in this topic. However such coarse-grained evaluations offer limited insight into how to modify curriculum and teaching approaches. Yet, the data presented in Ünal et al.’s paper also illustrate the potential for more in-depth studies to provide more detailed accounts of the nature of Turkish students’ thinking. These could be a starting point for understanding why Turkish school children come to think about the topic in this way, and so how teaching needs to be modified to better support progression in student learning. Ünal et al. provide a good example of the kind of data that researchers can obtain, but one suspects that a more nuanced analytical framework could have revealed many more insights about the knowledge and understanding of their student informants. Taber / TUSED / 8(1) 2011 16 REFERENCE Anderson, L. W., & Krathwohl, D. R. (2001). A Taxonomy for Learning, Teaching and Assessing: A revision of Bloom's taxonomy of educational objectives. New York: Longman. Bell, B. (1995). Interviewing: a technique for assessing science knowledge. In S. M. Glynn & R. Duit (Eds.), Learning Science in the Schools: Research Reforming Practice (pp. 347364). Mahwah, New Jersey: Lawrence Erlbaum Associates. Bloom, B. S. (1968). The cognitive domain. In L. H. Clark (Ed.), Strategies and Tactics in Secondary School Teaching: a book of readings (pp. 49-55). London: MacMillan. Bruner, J. S. (1960). The Process of Education. New York: Vintage Books. Claxton, G. (1993). Minitheories: a preliminary model for learning science. In P. J. Black & A. M. Lucas (Eds.), Children’s Informal Ideas in Science (pp. 45-61). London: Routledge. Coll, R. K., & Treagust, D. F. (2003). Investigation of Secondary School, Undergraduate, and Graduate Learners’ Mental Models of Ionic Bonding. Journal of Research in Science Teaching, 40(5), 464-486. diSessa, A. A. (1993). Towards an epistemology of physics. Cognition and Instruction, 10(2&3), 105-225. Driver, R., & Erickson, G. (1983). Theories-in-action: some theoretical and empirical issues in the study of students’ conceptual frameworks in science. Studies in Science Education, 10, 37-60. Duit, R. (2009). Bibliography - Students' and Teachers' Conceptions and Science Education. Kiel: http://www.ipn.uni-kiel.de/aktuell/stcse/stcse.html. Gilbert, J. K., Osborne, R. J., & Fensham, P. J. (1982). Children’s science and its consequences for teaching. Science Education, 66(4), 623-633. Gilbert, J. K., & Watts, D. M. (1983). Concepts, misconceptions and alternative conceptions: changing perspectives in science education. Studies in Science Education, 10, 61-98. Gilbert, J. K., Watts, D. M., & Osborne, R. J. (1985). Eliciting student views using an interview-about-instances technique. In L. H. T. West & A. L. Pines (Eds.), Cognitive Structure and Conceptual Change (pp. 11-27). London: Academic Press. Gilbert, J. K., & Zylbersztajn, A. (1985). A conceptual framework for science education: The case study of force and movement. European Journal of Science Education, 7(2), 107120. Griffiths, A. K., & Preston, K. R. (1992). Grade-12 students’ misconceptions relating to fundamental characteristics of atoms and molecules. Journal of Research in Science Teaching, 29(6), 611-628. Hofstein, A., Levy Nahum, T., Mamlok-Naaman, R., & Taber, K. S. (2010). Teaching and learning the concept of chemical bonding. Studies in Science Education, 46(2), 179-207. Justi, R., & Gilbert, J. K. (2000). History and philosophy of science through models: some challenges in the case of ‘the atom’. International Journal of Science Education, 22(9), 993-1009. Taber / TUSED / 8(1) 2011 17 McCloskey, M. (1983). Intuitive physics. Scientific American, 248(4), 114-122. Millar, R. (Ed.). (1989). Doing Science: images of science in science education. London: The Falmer Press. Nakiboglu, C., & Taber, K. S. (2010). Turkish students' perceptions of the atom in relation to a common teaching analogy. Paper presented at the International Science Education Symposium on the theme of Particulate and Structural Concepts of Matter. Nakiboğlu, C., Tsaparlis, G., & Taber, K. S. (2009). Student understanding of ionic bonding in three countries: molecular versus electrostatic thinking. Paper presented at the European Science Education Research Association Conference. Nicoll, G. (2001). A report of undergraduates’ bonding misconceptions. International Journal of Science Education, 23(7), 707-730. Özmen, H. (2004). Some student misconceptions in chemistry: a literature review of chemical bonding. Journal of Science Education and Technology, 13(2), 147-159. Peterson, R., Treagust, D., & Garnett, P. (1986). Identification of secondary students’ misconceptions of covalent bonding and structure concepts using a diagnostic instrument. Research In Science Education, 16, 40-48. Sánchez Gómez, P. J., & Martín, F. (2003). Quantum versus ‘classical’ chemistry in university chemistry education: A case study of the role of history in thinking the curriculum. Chemistry Education: Research & Practice, 4(2), 131-148. Solomon, J. (1993). Four frames for a field. In P. J. Black & A. M. Lucas (Eds.), Children’s Informal Ideas in Science (pp. 1-19). London: Routledge. Taber, K. S. (1994). Misunderstanding the Ionic Bond. Education in Chemistry, 31(4), 100103. Taber, K. S. (1998). An alternative conceptual framework from chemistry education. International Journal of Science Education, 20(5), 597-608. Taber, K. S. (2000a). Case studies and generalisability - grounded theory and research in science education. International Journal of Science Education, 22(5), 469-487. Taber, K. S. (2000b). Finding the optimum level of simplification: the case of teaching about heat and temperature. Physics Education, 35(5), 320-325. Taber, K. S. (2001). The mismatch between assumed prior knowledge and the learner’s conceptions: a typology of learning impediments. Educational Studies, 27(2), 159-171. Taber, K. S. (2002). Chemical Misconceptions - Prevention, Diagnosis and Cure: Theoretical background (Vol. 1). London: Royal Society of Chemistry. Taber, K. S. (2003). The atom in the chemistry curriculum: fundamental concept, teaching model or epistemological obstacle? Foundations of Chemistry, 5(1), 43-84. Taber, K. S. (2007). Classroom-based research and evidence-based practice: a guide for teachers. London: SAGE. Taber, K. S. (2008). Exploring conceptual integration in student thinking: evidence from a case study. International Journal of Science Education, 30(14), 1915-1943. Taber, K. S. (2009). Progressing Science Education: Constructing the scientific research programme into the contingent nature of learning science. Dordrecht: Springer. Taber / TUSED / 8(1) 2011 18 Taber, K. S. (2010). Straw men and false dichotomies: Overcoming philosophical confusion in chemical education. Journal of Chemical Education, 87(5), 552-558. Taber, K. S., & Coll, R. K. (2002). Chemical bonding. In J. K. Gilbert, O. de Jong, R. Justi, D. F. Treagust & J. H. Van Driel (Eds.), Chemical Education: Research-based Practice (pp. 213-234). Dordrecht: Kluwer Academic Publishers BV. Taber, K. S., & Tan, K. C. D. (2011). The insidious nature of ‘hard core’ alternative conceptions: Implications for the constructivist research programme of patterns in high school students’ and pre-service teachers’ thinking about ionisation energy. International Journal of Science Education, 33(2), 259-297. Taber, K. S., & Watts, M. (1996). The secret life of the chemical bond: students’ anthropomorphic and animistic references to bonding. International Journal of Science Education, 18(5), 557-568. Ünal, S., Çalık, M., Ayas, A. ü., & Coll, R. K. (2006). A review of chemical bonding studies: needs, aims, methods of exploring students' conceptions, general knowledge claims and students' alternative conceptions. Research in Science & Technological Education, 24(2), 141 - 172. Ünal, S., Coştu, B., & Ayas, A. (2010). Secondary school students’ misconceptions of covalent bonding. Journal of Turkish Science Education, 7(2), 3-29. Watts, M., & Zylbersztajn, A. (1981). A survey of some children’s ideas about force. Physics Education, 16(6), 360-365. White, R. T. (1985). Interview protocols and dimensions of cognitive structure. In L. H. T. West & A. L. Pines (Eds.), Cognitive Structure and Conceptual Change (pp. 51-59). London: Academic Press. Copyright of Journal of Turkish Science Education (TUSED) is the property of Journal of Turkish Science Education and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. 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