CAN UNDERGRADUATES REASON SCIENTIFICALLY? BOO HONG KWEN National Institute of Education Nanyang Technological University ABSTRACT This paper reports on work which is an extension of the work previously reported in Boo (1996) which involved A-level chemistry students. The present paper reports on nvestigative studies conducted with university undergraduates in chemistry to examine their ability to reason scientifically when confronted with a range of chemical phenomena. The chief data collection instrument is the clinical interview. Five familiar chemical reactions were used as foci for discussion in the interviews; during which interviewees were asked to make predictions about the type of change expected, including the overall energy change involved. They were also asked to describe how they thought the change proceeded at the microscopic level as well as to explain why they thought the change took place at all. Descriptors: chemistry, scientific reasoning, chemical reactions, Purpose of Study The purpose of the study is to investigate the scientific thinking ability of a class of 12 fourth year undergraduate chemistry students enrolled in the B.Sc. with Dip Ed course at the National Institute of Education. Background of Study In the literature, the term 'scientific reasoning' or 'scientific thinking' appears to refer to science process skills, which in turn have also been described as 'the scientific method' and/or 'critical thinking skills' (Padilla, 1991). In this paper, the term 'scientific reasoning' is derived from a consideration of the nature of science as " the attempt to make the chaotic diversity of our sense-experience correspond to a logical uniform system of thought" (Einstein, 1954, pp. 323) and the aim of science as "the establishment of generalisations governing the behaviour of the world (Chalmers, 1990, pp. 29). Based on consideration of the nature and aim of science, it can be seen that scientific reasoning includes, among other things, inductive thinking (or the inferring of a general concept, principle or law from particular instances) and deductive thinking (or the inferring of particular instances from a general concept, principle or law). It also includes 'the ability to use a minimum number of concepts, principles, models to make explanations and/or predictions of a wide range of natural phenomena.' Defined in this way, it is within the domain of science process skills - that of interpretation or inferring from data. Studies on scientific thinking of pupils have been centred around two main areas: firstly, the domain of the science process skills (Germann, Aram & Burke, 1996) and, secondly, the domain of pupils' use of science concepts and naive ideas or alternative conceptions. With respect to the first domain, research and development has included the identification of science process skills (e.g. Livermore, 1964; Gagne, 1970; Funk, Okey, Fiel, Jaus & Sprague, 1979; Dillashaw & Okey, 1980; Tamir & Lunetta, 1981); development of materials and strategies for teaching these skills (e.g., Lunetta & Tamir, 1981) and assessment of pupils' acquisition of these skills (e.g., Tamir, Nussinovitz & Friedler, 1982). With respect to the second domain there is now copious information on pupils' use of science concepts and naive ideas or alternative conceptions in various topics (Pfundt & Duit, 1991; Carmicheal et al., 1991). A previous study (Boo, 1996) found that A-level chemistry students (11th and 12th graders) were lacking in ability to think scientifically. The present study is directed at investigating students' scientific reasoning in terms of their understanding of concepts and principles and their ability to apply it consistently across a range of phenomena. Method of Study The study is based on students' explanations of four key aspects of chemical reactions measured over five events, and the instrument used for data collection is the interview-about-events (Osborne and Gilbert, 1980; Gilbert, Watts and Osborne, 1985). The five events were: 1.hot copper in air; 2.the burning candle; 3.the bunsen flame; 4.addition of magnesium to dilute hydrochloric acid; and 5.addition of aqueous lead nitrate to aqueous sodium chloride. The four aspects were: A.the type of change predicted; B. the overall energy change predicted; C. how the process of change is conceived or imagined; and D.the driving force for the change. Each study subject was interviewed on a one to one basis. Each interview session, of about 1 hour duration, was audio-taped and subsequently transcribed. During each interview students were not only asked to verbalise their understandings of various aspects of the concept of chemical reaction but were also asked to make drawings to illustrate their explanations and theories. The sample comprised the entire fourth year chemistry undergraduate class (N=12), all of whom were females. Findings and discussion Results showed that the majority of the subjects had learned chemistry by rote (which was evident in the way subjects tried to invoke recall and memory in the responses) and were unable to appreciate the nature of science concepts and principles. To them, key science concepts (e.g., metal, combustion) appeared to be mere labels or terms; and do not represent generalisations or abstractions from experience with more than one object, phenomenon or fact. Hence to them, concepts do not hold any power of prediction and pervasive explanations. The following are some specific instances: Event 1 Hot copper in air While eight of the twelve subjects recognised that this a combustion reaction involving copper metal and oxygen, four of them failed to use concepts of activation energy, bond breaking, bond making and strengths of bonds formed vis-à-vis bonds broken to deduce that it should be an overall exothermic reaction. Instead, they appeared to be misled by perceptual clues and suggested that the reaction is overall endothermic because heat was seen as the causal agent of change. As expressed by one of the students, "you actually heat up the thing, so you actually need energy for the reaction to take place, so it is an endothermic reaction." Event 2 The burning candle With respect to this event, eight out of the twelve subjects thought that the candle wax was not involved in burning. To these students, only the candle wick was involved in burning. While one would find such an inference from a layman (made on observing a burning candle) understandable, it is less understandable coming from fourth year chemistry undergraduates. These undergraduate students appeared to be using what Driver (1985) desrcibed as "perceptual reasoning" rather than "conceptual reasoning". Event 3 The bunsen flame Although eleven out of the twelve students interviewed had no difficulty in identifying the chemical changes involved, only four of them were able to account satisfactorily for the process of change or the mechanism involved. The others seemed unable to integrate concepts of homopolar bonds, bond fission, free radical reaction and so forth to suggest a plausible mechanism. Event 4 Addition of magnesium to dilute hydrochloric acid Eight out of the twelve subjects were unable to integrate various concepts that they have learnt (e.g., 'metal', 'strong acids' and redox reactions) to account for the microscopic aspects of the process of the reaction (i.e., aspect C) between magnesium metal and dilute aqueous hydrochloric acid (event 4). These eight students thought that the reaction involves electron transfer between magnesium and chlorine atoms rather than between magnesium atoms and hydrogen (or more accurately, hydroxonium) ions. Event 5 Addition of aqueous lead nitrate to aqueous sodium chloride Nine out of the twelve students interviewed were unable to use concepts of dissolving and dissociation of ionic solids to give satisfactory accounts of the process of reaction. Inability to apply scientific principles The fact that students have not fully grasped the conceptual meaning of terms means that they are unable to appreciate the full significance and predictive power of scientific concepts and principles. Evidences of this, among others, can be seen in their responses to the questions concerning aspects B and D across the five events, i.e., "Predict, giving reasons, the overall energy change involved" and "What do you think is the driving force for the change?" respectively. Students' responses revealed a general lack of ability to use the principle that "a reaction is overall exothermic if the bonds that are being made are stronger than the bonds which are being broken" (and the corresponding principle that "a reaction is overall endothermic if the bonds that are being made are weaker than the bonds that are being broken"). Instead, these students offered a range of different reasons why a particular reaction is exothermic or endothermic. The following responses given by one of the students, U8 is typical of the group (Note: No responses were recorded under event 2, the burning candle, because the student had stated that the candle wax is not involved in any chemical reaction.) Event Energy change Reasons 1 Endothermic Because without heat, there is no reaction.. copper metal has strong metallic bonds.. oxygen bond is also very strong.. so energy of these two bonds is greater than the ionic bond formed between copper & oxygen. 3 Exothermic Because you have methane.. you give it oxygen.. & you excite it.. it becomes a radical.. these are high energy things.. so they probably give out heat. 4 Exothermic Hydrogen chloride is in aqueous form.. free ions.. it's a matter of making Mg into cations so it kind of uses less energy.. & you're forming a covalent bond and an ionic bond.. 5 None Because you're breaking up two ionic bonds & forming two ionic bonds.. so no energy change. From these responses it could be seen that the student was not using a common principle across events in her explanation. In events 1 and 4 she appeared to be using some idea of relative strengths of bonds formed versus bonds broken; in event 5, she appeared to be using ideas about number of bonds formed versus number of bonds broken; and in event 3, she appeared to be using some naive idea about high energy radicals emitting heat. The students' responses on aspect D, the driving force for the change also revealed a similar general lack of ability to use the principle that "all changes, including chemical ones, are driven by the decrease in enthalpy, resulting in a more stable system or in increase in entropy in the universe." The following responses given by the student U8 is typical of the group (Note: No responses were recorded under event 2, the burning candle, because the student had stated that the candle wax is not involved in any chemical reaction.) Event Driving force 1 Heat supplied.. it breaks the copper & oxygen bonds so, the probability of forming copper oxide is there. 3 Heat.. which produces the free radicals.. the rate determining step.. the driving force is heat and the constant formation of these radicals. 4 The driving force is the formation of products which are more stable. 5 Now from those ions Na+, Cl-, Pb2+ & NO3-.. to form NaNO3 & PbCl2 .. these are more stable than these ions.. so that is the driving force. From the responses, the student appeared to be using some idea of relative stability of products versus reactants in accounting for the driving force in events 4 and 5, but in events 1 and 3, she appeared to be using naive ideas about heat input being the driving force. On comparing her responses on aspect B (overall energy change) and aspect D (driving force for change), an inconsistency became evident. For event 5, she had predicted overall no energy change and yet, when accounting for driving force, she stated that the products are more stable relative to reactants. And when her attention was drawn to the inconsistency, she appeared rather helpless and could not see any way out of addressing the inconsistency in her responses. Implications of study The finding that these students are generally lacking in ability to think scientifically in spite of having had several years of formal science education is a matter of grave concern. This raises questions concerning their understanding of the nature of science as well as the kind of teaching as well as learning experiences that they have been through such as the following: * Have students been made aware of the nature and aims of science? * Have they been made aware of the meaning and nature of science concepts and principles? * Have they been taught to abstract concepts and generalisations, rather than been taught to learn facts in isolation? * Have they been taught to make connections between new concepts and their existing knowledge rather than to know concepts in isolation? If these students are unaware of the nature of science, and aim of science as the establishment of generalisations governing the behaviour of the world, and if they view science as essentially a collection of facts, then it would not be surprising that they would tend to compartmentalise knowledge, and learn by rote i.e., adopt surface learning approaches (Biggs, 1987), and hence lack the ability to think scientifically. If they are unaware of the nature of scientific concepts and principles, then it would not be surprising if they could not appreciate their generality and power in making predictions and explanations. And if they have not learned to construct meanings and generalisations based on facts and propositions, or if they have learned and applied concepts by rote (Garnett & Hackling, 1995) then it would not be surprising too that cannot think scientifically. Thus it appears that the science curricula content and implementation in schools as well as in teacher training programmes would need to be reviewed and scrutinised if students are learn to think scientifically. Perhaps, as suggested by Gilbert (1991), science education should begin with a consideration of the nature of science as "the process of constructing predictive conceptual models". And from there, to teaching the nature of scientific concepts, principles and models, with illustrations from the content itself. References Biggs, J. (1987) Students' Approaches to Learning and Studying. Hawthorn, Vic.: Australian Council for Educational Research. Boo, H.K. (1996). Consistency and inconsistency in A level students' understandings of a number of chemical reactions. Research in Science and Technological Education, 14(1), 55-66. Carmichael, P., Driver, R., Holding, B., Phillips, I., Twigger, D. and Watts, M (1991). Research on Students' Conceptions in Science: A Bibliography. Children's Learning in Science Research Group, University of Leeds. Cavallo, A. (1996). Meaningful learning, reasoning ability, and students' understanding and problem. Chalmers, A. (1990). Science and its Fabrication. Milton Keynes, Open University Press. Dillashaw, F.G., & Okey, J.R. (1980). Test of integrated process skills for secondary science students. Science Education, 64, 601-608. Driver, R. (1985). Beyond appearances: The conservation of matter under physical and chemical transformations. In: Driver, R., Guesne, E., Tiberghien, A. (Eds.) Children's Ideas in Science. Open University Press, Milton Keynes, 145-169. Einstein, A. (1954). Ideas and Opinions. New York: Crown. Funk, J.H., Okey, J.R., Fiel, R.H., Jaus, H.H., & Sprague, C.S. (1979). Learning process skills. Dubuque, IA: Kendall/Hunt. Gagne, R.M. (1970). The conditions of learning. New York: Holt, Rinehart & Winston. Garnett, P.J. & Hackling, M.W. (1995). Students' alternative conceptions in Chemistry: A review of research and implications for teaching and learning. Studies in Science Education, 25, 69- 95. Germann, P. J., Aram, R.A., & Burke, G. (1996). Identifying patterns and relationships among the responses of seventh-grade students to the science process skills of designing experiments. Journal of Research in Science Teaching, 33(1), 79-99. Gilbert, J., Watts, M., Osborne, R. (1985). Eliciting student views using an interview-about-instances technique. In : West, L., Pines, A. (Eds.), Conceptual Structure and Conceptual Change. London: Academic Press, 11-27. Gilbert, S.W. (1991). Model building and a definition of science education. Journal of Research in Science Teaching, 28, 73-79. Kuhn, D., Amsel, E. & O'Loughlin, M. (1988). The development of scientific thinking. New York: Hatcourt, Brace, Jovanovich. Livermore, A.H. (1964). The process approach of the AAAS Commission on Science Education. Journal of Research in Science Teaching, 2, 271-282. Lunetta, V.N., & Tamir, P. (1981). An analysis of laboratory activities: Project Physics and PSSC. School Science and Mathematics, 81, 635-641. Osborne, R., Gilbert, J. (1980). A method for investigating concept understanding in science. European Journal of Science Education, 2, 311-321. Padilla, M. J. (1991). Science activities, process skills, and thinking. In: Glynn, S., Yeany, R., Britton, B. (Eds) The Psychology of Learning Science. Lawrence Erlbaum Associates. Pfundt, H., Duit, R. (1991). Bibliography: Students' Alternative Frameworks and Science Education. 3rd ed. Kiel, Institute for Science Education, University of Kiel.. Tamir, P., & Lunetta, V.N. (1981). Inquiry related tasks in high school science laboratory handbooks. Science Education, 65, 477- 484. Tamir, P., Nussinovitz, R., & Friedler, Y. (1982). The design and use of practical tests assessment inventory. Journal of Biological Education, 16, 42-50. 9