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Asia-Pacific Forum
on Science Learning and Teaching, Volume 10, Issue 1, Article 3
(June, 2009) |
In the following, examples are given of how students made use of metaphors in the interviews. ‘CJ’ stands for the interviewer and the students were allocated fictitious names.
Example 1: Maria (M) (year 2, upper secondary level) was asked to interpret the picture of a cell membrane, in which different channel proteins were visible. She replaces the scientific term ‘receptor’ with the metaphor ‘flag’.
CJ: Can you tell me what’s happening here?
M: Well, I know that the protein lets substances in and out of the cell, substances that are needed for transport processes and the construction of various things, and what happens is that the protein picks up those substances that are outside of the cell, it has these...flags?... that help it to identify the substances. I can’t remember what they were called... something to do with flags in any case...
CJ: OK
M: ....and they act as signs so that the cell knows which substances are available and which should be taken up, and the protein itself can open to form a channel to let the useful substances in and then close again to stop other things from getting in. The protein can also transport things out of the cell.
CJ: These flags – are they on the molecules that the cell wants to take up?
M: No, they’re on the cell wall, I can’t remember. It’s like... I don’t know. In any case, I can’t remember properly, but they sort of sit on the outside of the cell and detect which substances are out there and which it wants to take up, and they take care of that. And the protein itself is like a pump that lets things in and out, and makes sure that neither too little nor too much is allowed into the cell, it opens and closes.
Example 2: Jonas (J) (year 3, upper secondary level) is asked if he can visualize a protein. He makes a metaphoric association to a wadded-up ball:
CJ: If I ask you to think about a protein, does any sort of image spring to mind?
J: Yes, it does. We’ve seen pictures in biology - a sort of ball, I guess, like a wadded-up ball, except that the threads are chains of amino acids.
This spontaneous metaphor reoccurs later in the interview when he is shown a picture of a folding protein:
CJ: Exactly. And what do you see on either side of this picture?
J: So you’ve got the wadded-up ball on one side, and a non-wounded-up string or thread on the other....
Example 3: Erika (E) (year 3, upper secondary level) is shown the visualization of the process of protein synthesis. To describe the conformational change in DNA at the beginning of transcription, she makes a metaphoric association to a ball of yarn.
CJ: Do you recognize this picture? Do you know what it represents?
E: Yeah.... it’s DNA, transcription and stuff...
CJ: Yes, quite. Could you tell me what’s happening? If we start here, with the DNA in the nucleus, can you tell me what happens here to begin with?
E: Hmmm, I’ll have to think.... to begin with, it’s all wrapped up like a ball of yarn, and then it folds itself up, I think.
CJ: Do you mean the DNA?
E: Yeah, the DNA
The metaphors in the examples above are:
Erika: Wrapped up like a ball of yarn, a spontaneous or teaching metaphor which describes the conformational change in the DNA at the start of transcription. Beside the metaphorical association to a ball of yarn, Erika uses a verb, wrap up (veckla upp), which connotes to everyday events.
Jonas: A wadded-up ball, a spontaneous metaphor which he uses both as a description of his mental image of a protein and to describe a visual representation of a folding protein. The fact that he uses this spontaneous metaphor twice during the interview seems to indicate that it connects to something central in how he perceives a protein. It can also be noted that his addition of the adjective ‘wadded-up’ makes the metaphor more specific and also slightly more advanced, and thus a better description of the three-dimensional structure of a protein molecule, as compared to the simple metaphor ‘ball’, which merely refers to a rounded sphere.
Jonas: threads, chains of amino acids, which Jonas uses to refer to a protein molecule, metaphors that are also used in science.
Maria: Flag, by which she describes a structure projecting from the outside of the cell membrane (which she by a slip of tongue calls cell wall’ instead). From her reasoning it is possible to determine that she uses the metaphor ‘flag’ to signify the biomolecular concept of receptor. When she was later asked what she had intended with the word ‘flag’, it could be confirmed that she actually meant ‘receptor’, although her conception of receptor seemed to be vague – which is natural at upper secondary level, as the receptor concept is examined more in depth first at tertiary level. She recalled that she had got the metaphor ‘flag’ from a certain section of a prior course in natural science, and that the metaphor had been introduced by her teacher. Furthermore, from the transcript, it seems likely that she confuses the concept of specificity of channel proteins and the concept of surface receptors.
It is a striking feature of the interview transcripts that the students actually reason in a way that shows that they have grasped important aspects of the scientific content, at the same time as they have difficulty in using the proper scientific terminology.
In answer to the question whether the students’ use of metaphors changes while learning about protein function from upper secondary to tertiary level, the results presented in Figure 2 show that the use of metaphors decreases, while the use of domain-specific expressions increases. Deictic expressions used to refer to various aspects of the animations remain relatively stable, albeit slightly decreasing, over time with increasing level of education.
Figure 2. The relative frequency (%) of use of the four categories of expressions: Deictic expressions, Metaphors and Domain-specific expressions by the upper secondary and tertiary students in this study. (n=55)
