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Energy can be created, but only in biology
Energy can be made, but only in biology: Amy had learnt that respiration was converting glucose and oxygen into energy - but had learnt in physics that energy cannot be made
Amy was a participant in the Understanding Science Project.
Amy was a Y10 (14-15 year old) student who had separate lessons in biology, chemistry and physics. When I spoke to her, in biology she was studying respiration which she suggested was “converting glucose and oxygen into energy…through anaerobic respiration and aerobic respiration”, which involved “converting glucose into energy, glucose and oxygen into energy and either carbon dioxide and lactic acid, or just carbon dioxide. Something like that”.
In physics lessons she had been studying the topic of electricity, and she recognised that energy was an idea which appeared in both topics:
Interviewer: “the work in physics on electricity and the work in biology on respiration, is there any connection there?”
Amy: “Well in respiration energy is produced, and in physics energy is stored in a battery or a power supply and that then travels round - the circuit.”
When I spoke to her some weeks later Amy repeated that respiration was “converting oxygen and glucose into energy and carbon dioxide”. She told me that this was important “because it produces energy which like in humans your body needs, well in anything, your body needs and to grow and move and things like that”. She also told me that trees were “living and they need to produce energy and when they photosynthesise they produce like energy anyway” but that she obtained energy “through food which is then erm broken down and converted into energy”.
Later in the same interview I asked her about her physics lessons, where she had been told that “there’s like different types of energy” and that it “cannot be made or destroyed, only converted”. Amy did not seen to have recognised any issue with how she understood the role of energy in biology, and what she was taught in physics, although on further questioning he seemed able to recast her biology knowledge to fit what she had been taught in physics:
I: So in physics, they tell you that you cannot make or destroy energy.
A: Yeah.
I: And in biology, they tell you that you can make energy from oxygen and glucose?
No response – Pause of c.2 seconds
I: But only in biology, not in physics?
A: Oh, erm, I suppose the energy, erm well in respiration, erm the energy must be converted from stored energy in food.
So in an interview context, where the linkage was explicitly pointed out, Amy was able to see that the principle learnt in physics should be applied in biology. However, she did not spontaneously make this link, without which the nature of the respiration was misunderstood (in terms of energy being created from matter). This would appear to be an example of a fragmentation learning impediment, where prior knowledge which is available, and needed to properly understand new teaching, is not recognised as relevant and so not used in new learning.
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Dr Keith S Taber kst24@cam.ac.uk
University of Cambridge Faculty of Education