Keith S. Taber

BUILDING THE STRUCTURAL CONCEPTS OF CHEMISTRY: SOME CONSIDERATIONS FROM EDUCATIONAL RESEARCH

This paper sets out to consider how educational research into the learning of structural aspects of chemistry might inform teaching practice. The paper is based around a review of research findings into learners’ difficulties in developing the scientific models of chemical structures (atoms, molecules, lattices etc.) This forms the second of the four sections into which the paper is organised. The paper begins by considering how ideas about the learning process can inform our understanding of alternative conceptions and frameworks in chemistry, and - therefore - how we should view the research reviewed in the second section. This is a consideration of the findings of studies into difficulties learning about the molecular model; atomic structure; molecular structure; and lattices. This review is followed by a section identifying some key ‘pedagogic impediments’ - alternative aspects of learners’ thinking that seem to derive from the way the subject is taught. In the final section some practical suggestions are made regarding how the teaching of chemistry may be revised to help learners construct the scientific models rather than develop the alternative conceptions. [Chem. Educ. Res. Pract. Eur.: 2001, 2, 123-158]

An alternative conceptual framework from chemistry education

The science education literature includes many claims that learners commonly hold alternative conceptual frameworks about aspects of the science curriculum, especially in physics. There has also been criticism of the general notion of ‘alternative frameworks’, although some of this would appear to be due to different authors using the same terms in distinct ways. In this paper it is suggested that research evidence provides strong support for the view that many students of chemistry demonstrate similar alternative conceptions about some fundamental aspects of chemistry. These common alternative notions may be shown to be logically connected, and are here considered together to comprise a coherent alternative conceptual framework. Although it is not suggested that students will necessarily hold to all aspects of the framework, it is considered that the framework is a useful model of alternative thinking that teachers of chemistry should expect to find among their students.

Revisiting the chemistry triplet: drawing upon the nature of chemical knowledge and the psychology of learning to inform chemistry education

Much scholarship in chemical education draws upon the model of there being three ‘levels’ at which the teaching and learning of chemistry operates, a notion which is often represented graphically in terms of a triangle with the apices labelled as macroscopic, submicroscopic and symbolic. This model was proposed by Johnstone who argued that chemistry education needs to take into account ideas deriving from psychological research on cognition about how information is processed in learning. Johnstones model, or the ‘chemistry triplet’, has been widely taken-up in chemistry education, but has also been developed and reconceptualised in diverse ways such that there is no canonical form generally adopted in the community. Three decades on from the introduction of Johnstones model of the three levels, the present perspective article revisits both the analysis of chemical knowledge itself, and key ideas from the learning sciences that can offer insights into how to best teach the macroscopic, submicroscopic and symbolic aspects of chemical knowledge.

The secret life of the chemical bond: students’ anthropomorphic and animistic references to bonding

This paper discusses students’ use of anthropomorphic language in science, and in particular calls upon some examples from research into student understanding of chemical bonding. It is argued that anthropomorphic language is common amongst scientists as well as science students. A simple classification of such instances is suggested to distinguish between those examples that are useful in aiding communication and understanding, and those which merely stand in place of such understanding.

Development of Student Understanding: a case study of stability and lability in cognitive structure

Abstract This paper presents findings from a case study into the development of student understanding of a complex and abstract scientific concept: chemical bonding. The case study reveals significant progression in student understanding, but also highlights issues of how such progression should be addressed. Particular emphasis is given to the factors that were associated with ‘blocks’ to appropriate concept development. The learner discussed had her own ‘alternative conceptions’ of ionic charge and electrostatic attraction that, lacking the appropriate background knowledge, she used in order to make sense of chemistry. These alternative ideas blocked the development of an electrostatic framework for bonding to replace the ‘full outer shell heuristic’ used at the General Certificate of Secondary Education (GCSE) level, and had repercussions for the understanding of a range of related concepts. The importance of diagnosing learners’ alternative ideas is thus demonstrated, and some of the problems of carry...

Learning at the Symbolic Level

Abstract The symbolic language of chemistry is extensive, and is used ubiquitously in teaching and learning the subject at secondary level and beyond. This chapter considers how this ‘language’, which acts as such a powerful facilitator of communication for the expert, may often impede effective communication for novice learners. Symbolic representations become second nature to the teacher, being highly integrated with conceptual understanding and subject knowledge. However, such representations may make considerable additional demands on learners already challenged by both the abstract nature of concepts and the range of unfamiliar substances to which these concepts are applied in the curriculum. Drawing upon a broadly constructivist perspective on learning, the chapter explores three aspects of learning about the representational level in chemistry. The range of representations that are used in teaching and learning chemistry at school and college levels is outlined, drawing attention to the demands this makes of those setting out on a study of chemistry. The particular example of the ‘chemical equation’ is then considered in some depth to illustrate the extent to which representational features are linked to underlying chemical theory, and how students are expected to appreciate the nuanced distinctions between different variations in representation (whilst ignoring trivial stylistic variations). Finally the role of the symbolic level of representation as a mediator between the molar and sub-microscopic levels of chemistry is considered, and how this offers potential to compound student learning difficulties, but also opportunities for reinforcing student understanding. Throughout the chapter there is an emphasis on where teachers need to give careful thought to support student learning and facilitate progression in the subject.

LEARNERS’ EXPLANATIONS FOR CHEMICAL PHENOMENA

There is a growing body of research which explores the nature of explanation in science classrooms. The vast majority of this work highlights the teacher’s role as explainer of scientific phenomena, while little has explored the quality of learners’ own explanations. This paper helps redress this inbalance by undertaking an analysis of students’ explanations related to aspects of chemical structure and bonding. In this paper we set out our results - an analytical framework for exploring the explanations produced by students within the context of a chemistry course. The primary source of data used in this research derives from interviews with students in the U.K. studying chemistry at University entrance level. These interviews were undertaken as part of a longitudinal study of the development of students’ understanding of the chemical bond concept. The data collected has been interrogated to develop an analytical model of learners’ explanations in chemistry. [Chem. Educ. Res. Pract. Eur.: 2000, 1, 329-353]

The Sharing-Out of Nuclear Attraction: or "I Can't Think about Physics in Chemistry".

Pre‐university chemistry students were found to consider that an atomic nucleus gives rise to a certain amount of attractive force which is shared equally among the electrons. Students used this ‘conservation of force’ principle in their explanations of such phenomena as patterns in ionization energy. It is suggested that teachers of chemistry should be aware that although they may be using conventional electrostatic principles in their presentations, their students may be reinterpreting their explanations through this alternative conception. The present research concerns the interface between two scientific disciplines (chemistry and physics) and suggests that learners do not readily integrate their knowledge across such domains. It is mooted that more research into how such demarcations encourage learners to compartmentalize their knowledge may prove fruitful.

Conceptual Resources for Learning Science: Issues of transience and grain‐size in cognition and cognitive structure

Many studies into learners’ ideas in science have reported that aspects of learners’ thinking can be represented in terms of entities described in such terms as alternative conceptions or conceptual frameworks, which are considered to describe relatively stable aspects of conceptual knowledge that are represented in the learner’s memory and accessed in certain contexts. Other researchers have suggested that learners’ ideas elicited in research are often better understood as labile constructions formed in response to probes and generated from more elementary conceptual resources (e.g. phenomenological primitives or ‘p‐prims’). This ‘knowledge‐in‐pieces perspective’ (largely developed from studies of student thinking about physics topics), and the ‘alternative conceptions perspective’, suggests different pedagogic approaches. The present paper discusses issues raised by this area of work. Firstly, a model of cognition is considered within which the ‘knowledge‐in‐pieces’ and ‘alternative conceptions’ perspectives co‐exist. Secondly, this model is explored in terms of whether such a synthesis could offer fruitful insights by considering some candidate p‐prims from chemistry education. Finally, areas for developing testable predictions are outlined, to show how such a model can be a ‘refutable variant’ of a progressive research programme in learning science.

Learners’ Mental Models of the Particle Nature of Matter: A study of 16‐year‐old Swedish science students

The results presented here derive from a longitudinal study of Swedish upper secondary science students’ (16–19 years of age) developing understanding of key chemical concepts. The informants were 18 students from two different schools. The aim of the present study was to investigate the mental models of matter at the particulate level that learners develop. Data were collected using semi‐structured interviews based around the students’ own drawings of the atom, and of solids, liquids, and gases. The interview transcripts were analysed to identify patterns in the data that offer insight into aspects of student understanding. The findings are discussed in the specific curriculum context in Swedish schools. Results indicate that the teaching model of the atom (derived from Bohr’s model) commonly presented by teachers and textbook authors in Sweden gives the students an image of a disproportionately large and immobile nucleus, emphasises a planetary model of the atom and gives rise to a chain of logic leading to immobility in the solid state and molecular breakdown during phase transitions. The findings indicate that changes in teaching approaches are required to better support learners in developing mental models that reflect the intended target knowledge.