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Asia-Pacific Forum on Science Learning and Teaching, Volume 10, Issue 2, Article 2 (Dec., 2009) Mızrap BULUNUZ Undergraduate and masters students' understanding about properties of air and the forms of reasoning used to explain air phenomena |
In terms of initial understandings of properties of air, the students had many misconceptions, with a mean of only 42.4% of correct pretest answers. Some of the correct answers probably did not reflect a depth of understanding. Most of the questions that 50% or more of the participants answered correctly on the pretest are on concepts they could have memorized but not fully understood. They could not have experimented with the lack of air in space, and probably none of them had analyzed the composition of air inhaled and exhaled. These topics were not discussed in class. Therefore, it would not be expected that correct answers would increase on the posttest. In fact, on none of these questions was there a major increase from pretest to posttest; and on half of the questions, the percentage correct decreased slightly on the posttest, suggesting that the students may have guessed on both the pretest and the posttest.
For items on which most students got fewer than 50% correct on the pretest, the frequency of correct responses more than doubled on the posttest (from 25% to 52% correct). The one question that no one answered correctly on the pretest, was answered correctly by 63% on the posttest. The hands-on activities and discrepant demonstrations appeared to clarify many of the misconceptions held by the students. This finding is consistent with other research that found preservice (Kelly, 2000; Gibson et al, 2001) and inservice teachers' (Bulunuz & Jarrett, in press; Ebert & Elliot, 2002) understandings about science concepts can be improved by using hands-on activities and demonstrations. It corresponds with the observations of Borghi et al. (1998) that improvement in understanding is promoted by experimentation.
However, the analysis of reasoning used by the students in answering questions in their journals indicated that the students tended to focus on what was happening, using phenomena-based reasoning or relation-based reasoning, but few explained why it was happening using model-based reasoning. Some students tried to explain phenomena by discussing the relationships between the observable features, but these were incomplete explanations. For example, “blowing through straw creates pressure and lifts water out of straw--- the air you blow goes into vertical straw and makes water spray out.” That student was aware that blowing creates a kind of pressure but did not mention that stationary air has higher pressure than flowing air. That fewer students in this study used model-based reasoning than the students in the Leite and Afonso (2004) study may be explained by a difference in science background between the two samples. To correctly use model-based reasoning requires background knowledge the elementary school preservice and inservice teachers may not have had.
On the posttest, students were more successful on the observation questions (e.g., blowing under a paper bridge causes it to bend toward the table) than on the interpretation/ explanation questions (e.g., in a spray gun, the sprayed material comes out from the bottle because of a decrease in pressure at the end of the pipe). Given the limited explanations in their journals, some of the students may have observed what was occurring without understanding why it was occurring. According to epistemological reasoning theory (Driver et al., 1996), understanding is different from correct observation. In order to explain scientific concepts, students and teachers should demonstrate a high level of epistemological (model-based) reasoning (MBR). Teachers cannot teach for understanding unless they understand. To increase understanding, more time may have been needed for investigation and reflection. In the two sessions on air, there was little time for questions and discussion that could have promoted deeper understanding.
This study adapted a survey, first developed for middle school students, for use with preservice and inservice teachers. Ten journals were analyzed for a glimpse into the reasoning used by the participants in explaining the phenomena they observed through demonstrations and activities. The findings are intriguing in suggesting connections between understanding and reasoning. Further research on this topic could be strengthened by the addition of interviews to probe student understanding and the analysis of the reasoning used in all the journals. If all journals were to be analyzed for reasoning, the type of reasoning used could be correlated with answers on the posttest.
The findings of this study suggest ways in which both the survey instrument and the activities and demonstrations could be improved. This study employed an instrument on air phenomena that has potential for future studies. However the present instrument included questions beyond the possibility of experimentation (e.g., lack of air on the moon). It was useful in assessing initial understanding but some of the questions were not appropriate for a pretest/posttest analysis. To assess the effectiveness of demonstrations and activities in conceptual change, the assessment instrument should be limited to phenomena appropriate for demonstrations and activities. A lesson learned about demonstrations and activities was that more time was needed, with opportunity to discuss, reflect and perhaps do additional reading. More time would have helped students build deeper understandings about air properties and would have better modeled how to teach these topics to elementary school students.
In order to help children develop a scientific understanding about air, teachers must have clear understandings about properties of air. However, this study found that both the preservice and the inservice teachers held many initial misconceptions on the physical properties of air. The lack of research with preservice and inservice elementary teachers on these concepts suggests that properties of air are not generally covered in science methods classes. Given that the understanding of many phenomena including weather, airplane flight, cooking at various altitudes and tire pressure require an understanding of the properties of air, we recommend inclusion of activities on air phenomena in teacher education programs. With revisions to the assessment instrument, future research can better probe the effectiveness of such activities on teacher understanding. However, understanding accepted theory on air properties is not sufficient. Teachers should be explicitly introduced to the three types of reasoning with a focus on helping them become more effective model-based reasoners. Personal understanding and reasoning ability are important building blocks for teachers who will provide appropriate experiences, ask probing questions and guide their young students toward scientific understanding about air properties and other difficult concepts.
