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Asia-Pacific
Forum on Science Learning and Teaching, Volume 5, Issue 3, Article
8 (Dec., 2004) Yeung Chung LEE and Pun Hon NG Hong Kong primary pupils' cognitive understanding and reasoning in conducting science investigation: A pilot study on the topic of "Keeping Warm"
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Data analysis and discussion
Pupils' plans
As far as planning is concerned, pupils showed considerable limitation in measuring the dependent variable. Most pupils failed to measure the initial water temperature. As shown by the observers' notes, one reason is that at least some pupils did not realize that they needed to have some measures to indicate the rate of heat loss so that they could compare the ability of different cups in keeping warm with sufficient validity. Another reason is that many pupils assumed that the initial water temperature was the same for all cups since they used the same hot water. In comparison, Primary 5 pupils seemed to have a better understanding of how to design measurements to obtain more valid and reliable results. More Primary 5 than Primary 4 pupils took readings at regular intervals, demonstrating an initial grasp of the concept of rate of heat loss. There was also evidence that pupils' prior understanding of science concepts was influential when planning investigations. A few Primary 4 pupils thought that keeping warm meant elevation of water temperature rather than slowing the decrease in temperature.
As to the control of variables, the results show that Primary 5 pupils seemed to be more aware of the factors needed to be controlled than their Primary 4 counterparts since a slightly greater proportion of pupils in this grade level recognized the need to control the volume of water used in each cup. However, most pupils did not mention other relevant variables such as the place where they put the cups. It was noticed that some pupils placed the cups on different materials, like the table or a plastic tray.
Implementation of the plans
The results show that many groups did not adhere strictly to their plans and tended to make ad hoc decisions on certain steps. This could be due to their lack of experience in conducting investigations, hence limiting their foresight in planning. Primary 5 pupils were in general more able to introduce ad hoc steps to improve the validity of their data (e.g. by measuring the initial water temperature) and to control variables like the volume of water used for each cup.
Many pupils tended to manipulate the experimental set-up with their hands while waiting for results, which inevitably introduced other variables to the experiment. This was more common in Primary 4 than in Primary 5, presumably due to their lower level of maturity. A possible explanation of this kind of behaviours is that these young pupils tended to use their own senses to check the changes in the experiment, like how hot or how cool the water became at a particular moment. However, they did so without realizing that this is at odds with the nature of scientific inquiry which emphasizes a high degree of objectivity in measuring and the need to control variables in order to ensure reliability and validity. Another interesting phenomenon reflected by the findings is that a few groups of pupils were so insistent on their predictions that they had tried to manipulate the experimental procedure to obtain more "desirable" results. Again, this may be explained in terms of different levels of maturity of the pupils and their limited understanding of the purpose of scientific investigation. It also underscores the persistence of pupils' preconceptions and the influences of these preconceptions on their learning.
Pupils' evaluation
The results show that primary pupils were able to reflect on their experiences in investigations, which is an important attribute of scientific thinking. Both Primary 4 and 5 pupils were not short of ideas about how to improve their experimental design based on their previous trials. It appears that Primary 5 pupils were more logical than their Primary 4 counterparts in their reasoning. A greater proportion of Primary 5 pupils were able to suggest additional variables needed to be controlled, for example, the thermometers used should be comparable with each other, and equal volumes of water should be used for each cup. It is quite interesting to observe that Primary 5 pupils were more prone to adhere to their own predictions than Primary 4 pupils even though the observed data indicated otherwise. As a result, these pupils tended to come up with different hypotheses to explain their seemingly "anomalous" results. For instance, they attributed the differences in final temperature between different cups to heat loss while water was poured out, or to the fact that the thermometers were immersed at different depths in different cups. This finding seems to contradict the argument that older pupils should be more sophisticated in scientific reasoning than younger ones. Further investigation is needed to confirm this finding.
Those pupils who considered that the results were accurate tended to attribute this to the use of instruments for taking measurements, particularly thermometers, and to a much lesser extent, measuring cups. This indicates that some pupils seemed to have a preconception that these measuring instruments were of utmost importance to getting valid results, to the extent that they were fool-proof. Even more note-worthy is the misconception of a few Primary 4 pupils that the results of science experiments must be accurate, reflecting stereotyped reasoning. This is akin to what Driver et al (1996) referred to as "blind authority". This type of reasoning seems to be characteristics of what researchers described as "phenomenon-based reasoning" in which reasoning is based on surface phenomena rather than on a more in-depth consideration of the evidence presented (Driver et al. 1996; Tytler and Peterson 2004). Pupils also went further to suggest improvements to the task. One Primary 5 pupil commented that the number of cups for testing should not be limited to three. This was echoed by two Primary 4 pupils who suggested that other cups made from different materials should also be tested. There were other suggestions which seemed to be based on some sorts of reasoning though not explicitly spelt out, like using more water in each cup, using hotter water at the beginning of the experiment, and covering the cup with a lid.
Copyright (C) 2004 HKIEd APFSLT. Volume 5, Issue 3, Article 8 (Dec., 2004). All Rights Reserved.
