 |
Asia-Pacific Forum on Science Learning and Teaching, Volume 11, Issue 1,
Foreword (Jun., 2010) John K. GILBERT The role of visual representations in the learning and teaching of science: An introduction
|
|
|
Asia-Pacific Forum on Science Learning and Teaching, Volume 11, Issue 1,
Foreword (Jun., 2010) John K. GILBERT The role of visual representations in the learning and teaching of science: An introduction
|
Modelling, Models, and Visualization
The world-as-experienced is too complex to understand immediately in its entirety. Science ‘cuts it up’ into phenomena that are considered to be important and which can be comprehended. A typical phenomenon is that of movement. Simplified forms of a particular example of movement are then created that are thought to account for its properties, what it is composed of, and how that composition explains the properties displayed. This is the process of modeling and the outcomes are models. In the case of movement, generic models were produced, for example, in historical sequence by Aristotle, Newton, and Einstein. Representations are how we depict the models that we have created so that the individual concerned can perceive what has been done and can share that with others.
Visual representations exist in two ontological forms. The first of these is as internal representations which are the personal mentally constructions of an individual, otherwise known as mental images. The second of these is as external representations which are open to inspection by others. The literature, alas, refers to both of these forms as visualization (Gilbert 2008). I find it less confusing to use ‘external representation’ for that which people share and to reserve ‘visualization’ for internal representation.
In all learning and especially in that of science, individuals form three types of visualizations (internal representations). Building on the ideas of Johnstone and exemplified in the subject of chemistry (Gilbert and Treagust 2009), the first of these is the macro type. This depicts the empirical properties of the solid, liquid (including solution), colloid, gaseous, aerosol, phenomena which are of interest to chemists and which can be investigated with the instruments currently available. Macro representations thus permit the production of descriptive explanations (Gilbert, Boulter et al. 2000), which include the ascription of terminology to phenomena, a verbal output, and the production of measurements of their properties, which can be presented visually.
The second of these is the submicro type which depicts those entities, too small to be seen with an optical microscope (i.e. atoms, ions, molecules, free-radicals) and the bonding within and between them. These enable interpretative and causal explanations to be produced. That is, of what the model (and, of course, the phenomenon) are considered to consist and the causes of the properties that are measured.
The third of these is the symbolic type which depicts submicro entities using letters to represent elements, signs to represent electrical charges, subscripts to indicate the number of atoms in an individual species, subscripts to indicate physical state, and their incorporation into quantitatively balanced chemical equations for the macro phenomena and for any chemical changes that take place within them. As the definition states, the symbolic type of representation enables quantitative explanations to be produced i.e. those showing the amounts of entities involved.
Definitions for the types, whether three in number or more, for biology, physics, earth science, etc, can be produced analogically to the above. The full understanding of any phenomenon that falls within the remit of a science, at any point in the historical development of a field of enquiry, involves being able to produce visualizations of such types and being able to ‘move’ mentally between them. As we shall see later, this is a major goal of science education and has been found to be a major hurdle for many students.
Whilst visualizations can be produced without overt reference to the external world (this is the act of extreme, or original, creativity), many arise (in the manner sketched by Paivio) from the perception of external representations. The relation between an external representation and a visualization will depend on the purpose for, the focus of, and level of attention to, the stimulus provided. Inevitably, significant differences may arise between an external representation and the resulting visualization. In a similar way, the production of an external representation from a visualization may consequently and subsequently involve changes in what an individual felt was the original. The nature of expressed ideas does seem to depend on the producer’s expectations of the particular audience for the external representation and on the response being sought from that audience.
We initially tend to think of something new in terms of something with which we are more familiar. The existence of all visualization thus depends on the operation of metaphor and analogy, ideas that are often conflated.
Copyright (C) 2010 HKIEd APFSLT. Volume 11, Issue 1, Foreword (Jun., 2010). All Rights Reserved.
