 |
Asia-Pacific Forum
on Science Learning and Teaching, Volume 10, Issue 1, Article 3
(June, 2009) |
According to our empirical material, the concept of ‘protein’ can be referred to by students using several different terms (see Figure 3), ranging from scientific terms to metaphors and deictic expressions. However, the depth of intention with which the term is used cannot be judged from inspecting the term in isolation, but rather by an investigation of the context in which the term is used and in what way it is being used.
A protein can in different contexts be referred to as:
Figure 3. Model showing the continuity between metaphors and deictic expressions. The line extends from a more abstract, general and precise meaning on the left to a more vague and context-specific meaning on the right. From Rundgren (2006).
In an investigation of the context in which a term is used, it is possible to discuss the range of meaning, i. e. the specificity and generality or the vagueness and preciseness of the term. Let us look more closely at five terms used by the students in the investigation:
Figure 4. The model in Figure 1 applied to the scientific term ‘nitrogen base’, as it is used by the scientific community.
The term nitrogen base refers to a certain chemical compound that is a constituent part of the DNA and RNA molecules. There are four types of nitrogen bases in DNA and RNA, respectively, and their order determines the genetic information conveyed in the molecule. The concept of nitrogen base as a chemical compound and its function in the biochemistry of life is well established and defined in current science. Therefore, the meaning of the term ‘nitrogen base’ is general - it always refers to all entities of a certain kind – as well as precise (meets explicit criteria) - the referents are clearly defined, and there are no borderline cases (see Figure 4).
Figure 5. The model in Figure 1 applied to ‘flag’, a metaphor used in teaching by Maria’s teacher to convey the concept of ‘receptor’.
Figure 6. The model in Figure 1 applied to ‘flag’, as Maria uses the metaphor introduced by her teacher.
In the interview, Maria uses a metaphor from teaching, flag. When used by her teacher as a metaphor for receptors on the cell surface, the metaphor is actually quite precise in meaning (see Figure 5). However, when Maria uses the term (see Figure 6), the meaning is more vague. She uses the receptor concept in a context where she should actually speak about selective transport through channels, rather than about receptors. At the same time, she conveys a certain degree of understanding of the receptor concept, although the depth of intention with which she uses the term is less than that of her teacher. Still, without fully grasping the receptor concept, she uses the metaphor ‘flag’ with enough precision to make it possible for a person with adequate content knowledge to interpret the intended target of the metaphor. Outside this context, the word ‘flag’ has a wide range of meaning and refers to a number of objects that can be referred to as ‘flags’. In the everyday usage of the word, there can be a number of vague cases, such as a facial paint and waving cloths among football supporters. But as Maria uses the term here, we can distinguish a group of referents – receptors. At the same time, it is clear that she uses the term with a relatively less developed depth of intention as compared to an expert in the field.
Figure 7. The model in Figure 1 applied to the metaphors ‘ball’ and Jonas’ spontaneous metaphor ‘wadded-up ball’, both referring to a protein molecule.
The metaphor ‘ball’ refers to a wide array of objects. Its range of meaning is general, as it can be used to refer to all kinds of rounded objects, in this case molecular structures depicted as rounded shapes. Furthermore, the meaning is vague, because it is hard to make any exact definition of what can be referred to as a ‘ball’ and what cannot (see Figure 7). For example, if a child kicks a ballon, is it proper to call it a ‘ball’? Or what would we say if the same child uses a wadded-up newspaper? The terms of our everyday language often tend to have a vagueness and elastic quality that make them applicable in many differnt situations.
Jonas uses a metaphor, ‘wadded-up ball’, which makes the utterance more specific than the general metaphor ‘ball’, which in this context merely refers to a rounded shape. The addition of ‘wadded-up’ makes the possible group of targets to which the metaphor can refer more restricted. However, we must ask whether it makes the metaphor more precise. Our interpretation is that the metaphor has a relatively low degree of precision. It is specific rather than precise, because it must be seen in the proper context of the utterance to be understood correctly (see Figure 7). It has higher specificity than the simple metaphor ‘ball’, because the group of possible referents is more restricted. However, the metaphor is vague rather than precise as the referents are not clearly defined. There has been no attempt to delimit the central notion of ‘ball’. How round or non-round, how large or small, how smooth or rough, how solid or hollow, how elastic or non-elastic, is the ‘ball’, for instance? Without these delimitations, there might be a number of borderline cases in which the application of the term ‘ball’ could be uncertain or undecideable. Is a grain of sand a ‘ball’? Is the Globe in Stockholm a ‘ball’? In order to gain in preciseness, an expression must have less problematic borderline cases.
