"Holes" in Student Understanding: Addressing Prevalent

Research: Science and Education

“Holes” in Student Understanding: Addressing Prevalent Misconceptions Regarding Atmospheric Environmental Chemistry

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Sara C. Kerr Environmental Chemistry and Technology Program, University of Wisconsin–Madison, Madison, WI 53706 Kenneth A. Walz* Department of Chemistry, Madison Area Technical College, Madison, WI 53704; *[email protected]

The inclusion of environmental chemistry topics, including global climate change and ozone depletion, within the general chemistry curriculum provides an opportunity for students to apply chemistry principles to familiar issues and to gain an understanding of socially-important environmental problems, but the task is not without challenges (1). The complexity and intangible nature of atmospheric environmental phenomena lead to misconceptions among students. Since students have undoubtedly heard about these issues at some point in time, whether through previous schooling or through the media (2), they frequently have inaccurate preconceived notions of the nature of the problem. Specific misconceptions among student populations regarding global warming and ozone depletion have been documented in numerous studies. A survey of fourth-year secondary science education majors in the United States showed that, after taking the required courses, 56% held the idea that holes in the stratospheric ozone layer would increase the greenhouse effect (3). A survey of Australian students showed that approximately 40% of first-year students surveyed at the beginning of the semester also believed that the ozone hole causes global warming (4). Furthermore, Jeffries et al. surveyed first-year honors biology students in Britain and found that 67% believed global warming is caused by holes in the ozone layer and 58% thought that the greenhouse effect is made worse because more of the sun’s rays penetrate the atmosphere to reach the earth’s surface (5). Interestingly, 85% of the students in the Jeffries et al. study identified schools as their primary source of global environmental information compared to 56% and 53% identifying television and print media, respectively. One might expect that incomplete scientific descriptions provided by the media could cause confusion; however, it also appears that schools may be partly responsible for these misconceptions. Furthermore, the authors compared these same results to those collected in a survey conducted ten years earlier and found that student knowledge had not improved during this time span. The fact that many students entering college have misconceptions regarding environmental issues may be linked to the misconceptions held by their teachers. Boyes et al. administered a survey to undergraduates in a bachelor of education program after routine lectures and found that 89% thought ozone depletion would exacerbate the greenhouse effect (6). The authors suggest that the nature of these misconceptions may be that global environmental problems are often grouped together in textbooks and, since both are consequences of atmospheric pollution, they are hence linked in www.JCE.DivCHED.org

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the minds of students. Therefore, adopting a less holistic teaching strategy that dissects the different problems may help in addressing these misconceptions. The objective of this study was not only to qualitatively assess the misconceptions held by general chemistry students that entangle the greenhouse effect and the ozone hole, but also to address the misconceptions by implementing a series of data-analysis exercises that would allow students to gain a better conceptual understanding of these phenomena. We are not aware of any previous instructional materials that have been developed with this goal in mind or of any that have been subjected to an assessment of their effectiveness. Given that both global warming and ozone depletion involve large and complex systems that typically are involved in long term chemical phenomena, they do not lend themselves to laboratory experimentation. We hypothesized that by allowing students to explore the topics of climate change and ozone depletion via computer-based data-analysis exercises, they would develop a better grasp of the concepts than they might have via lecture-based instruction alone. We provided real data so the students could draw their own conclusions about various reaction mechanisms and potential solutions. This study employed four electronic data-analysis exercises that students completed individually using computer and Internet resources. The first three exercises addressed the greenhouse effect, stratospheric ozone, and tropospheric ozone individually, while the fourth exercise involved the integration of these three concepts. By first reducing the problems into separate units, we expected that the students would be able to compartmentalize the mechanisms involved in each problem. Then, in the integration component they would be able to examine the ways in which the various problems are similar to one another and be able to contrast between distinct chemical mechanisms and environmental impacts. Methodology The computer-based data-analysis exercises were introduced during lecture in a general chemistry class and were made available to students online through Blackboard Learning System software. For the first three exercises, the students were provided with electronic data sets, information on how the data were obtained, and a series of data manipulation tasks. The fourth exercise required students to link to additional online resources exploring various aspects of atmospheric chemistry. Students were required to complete all four exercises within one week working independently from one another.

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The first exercise required students to create and analyze graphs of annual mean CO2 concentration versus time using both recent atmospheric measurements collected at the Mauna Loa Observatory in Hawaii (7, 8) and long-term ice core data sets collected by the Arctic Research Institute (9). This exercise was meant to illustrate the greenhouse effect and global climate change. In the second exercise, students were required to create and analyze a plot of mean total ozone versus time using data collected by the British Antarctic Survey at Halley Station, Antarctica (10). This exercise showed how stratospheric ozone varied with annual seasons and illustrated the growth of the ozone hole since 1971. The third exercise required students to generate a plot of O3 and NOx concentrations versus time using data collected by the Wisconsin Department of Natural Resources in Milwaukee, Wisconsin (11). This exercise was designed to help students distinguish between the harmful effects of tropospheric ozone near the Earth’s surface and the benefits provided by stratospheric ozone present in the upper atmosphere. In the fourth exercise, students were directed to three existing Web sites to discover additional information and answer a series of questions regarding the chemical mechanisms associated with the ozone hole and global warming. This exercise was intended to help students synthesize the material from the first three exercises and distinguish between different chemical phenomena occurring in the atmosphere. To qualitatively assess the prevalence of misconceptions among first-year general chemistry students, we conducted a pre-assessment prior to implementing any instructional materials or lecturing on the topic. An identical post-assessment was administered after the students completed the electronic data-analysis exercises but before exposure to any lecture material. After completion of the post-assessment, lecture material was presented to clarify and emphasize important concepts. The students also participated in group discussions requiring critical thinking skills to further analyze the mechanisms involved in global warming, ozone depletion, and smog formation processes. A final assessment was then conducted to determine the students’ cumulative gains as a result of the online exercises in combination with the in-class lecture instruction and group discussion activities. Assessment data were collected from a total of 91 students. The number of students completing each of the individual assessments varied due to attendance and drops or withdrawals so all data are presented as percentage of students taking the assessment. Results The results of the pre-assessment showed that 17% of the students surveyed believed that global warming was caused by the hole in the ozone layer (Figure 1). An even greater percentage (40%) believed that global warming, due to the greenhouse effect, resulted in ozone destruction. Only 33% of the pre-assessment respondents identified the correct relationship between the greenhouse effect and ozone depletion. In response to an essay question asking students to describe global warming, one student said, “Global warming occurs because ozone is destroyed and more harmful rays can penetrate it, increasing the amount of energy that passes through.” Another wrote, “There is a depletion in ozone, let1694


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(1) The hole in the ozone layer triggers global warming. (2) Global warming due to the greenhouse effect results in ozone destruction. (3) Both the ozone hole and the greenhouse effect are caused by automobiles. (4) The greenhouse effect and the ozone hole are separate atmospheric phenomena that have different primary causes. (5) Global warming and the ozone hole are natural processes that have been occurring for millions of years. Figure 1. Student response on pre-, post-, and final assessments when asked to identify which statement accurately describes the relationship between the greenhouse effect and the ozone hole.

ting in extra energy, UV from sun, and small particles in the lower atmosphere trap this extra energy and temperatures go up.” Numerous students included similar statements in the pre-assessment essay response, clearly illustrating the misconceptions students held regarding the relationship between global warming and ozone. After completing the electronic data-analysis exercises, students showed moderate improvement in their performance on the environmental chemistry assessment questions with learning gains of 10–20% for each of the concepts assessed (Figure 2). Students demonstrated significant improvement in understanding on the final assessment after participating in the each of the data-analysis exercises, lecture sessions, and group discussion activities (Figures 1 and 2). During lectures and group discussions, we focused on mechanistic details, including the fate of incoming solar radiation, the role of atmospheric gases in creating the greenhouse effect, and the chemistry involved in ozone creation and destruction. We also included discussion of the plots analyzed by the students, emphasizing the temporal and geographical considerations pertinent to the different data sets and the numerous feedbacks, both positive and negative, affecting the global climate system. With this additional instruction, we saw gains of 30– 60% in student understanding on the final assessment. An impressive 90% of the students recognized that the greenhouse effect and the ozone hole are caused by different mechanisms. Thus, students’ overall understanding of atmospheric environmental chemistry improved dramatically.


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(1) Recognition that the greenhouse effect and the ozone hole are separate atmospheric phenomena that have different primary causes.

and lecture instruction helped students to address their preexisting ideas, accommodate the new knowledge, and construct a more accurate conceptual model of atmospheric phenomena. One limitation of this study was that we chose to implement the online exercises in isolation, in attempt to measure their effectiveness without the interfering effects of other instructional materials. This almost certainly is not the best use of these materials. In future courses (ones not involved in collecting research data) we envision the online exercises as being tightly integrated with both the lecture instruction and group discussions. If implemented this way, it is possible that even larger learning gains could be realized, further eliminating troublesome misconceptions and leading to a more enlightened understanding of atmospheric environmental chemistry.

(2) Recognition that global warming does not influence the amount of UV radiation reaching Earth’s surface.

Acknowledgments

(3) Recognition of the difference between stratospheric and tropospheric ozone and the environmental effects of each.

The authors gratefully acknowledge the Delta Program in Research, Teaching, & Learning at the University of Wisconsin–Madison, a project of the Center of the Integration of Research, Teaching, and Learning (CIRTL—Grant No. 0227592), and the Consortium for Education in Renewable Energy Technologies (CERET) (NSF/DUE-ATE 0202352). Special thanks go to Don Gillian-Daniel who helped to facilitate this research project and also to Robert Jeanne, Lillian Tong, and Kirsten Johnson for their assistance in the development of our instructional materials. The CO2 and temperature data used in the data-analysis exercises were provided by the U.S. Department of Energy through its Carbon Dioxide Information Analysis Center at Oak Ridge National Laboratory. The Halley mean total ozone data were provided by the British Antarctic Survey. Donalea Dinsmore at the Wisconsin Department of Natural Resources provided the ozone and ozone precursor data. The United Nations Environment Programme and GRID-Arendal provided the images included on the Climate Ark Web site (15) and linked to in the data-analysis exercise. The ozone hole tour Web site (16) is a project of the Centre for Atmospheric Science at Cambridge University, United Kingdom with the current version being designed and maintained by Glenn Carver. The individual emissions calculator Web site (17) linked to in the data-analysis exercise is a project of the Center for Neighborhood Technology. Dennis James provided valuable help facilitating the use of online exercises through the MATC Blackboard Web site. Wendy Suyama and Jennifer Jackowski assisted in the preparation of this manuscript.

(4) Recognition that CFCs are associated with the stratospheric ozone hole. (5) Recognition that the "hole" in the ozone layer causes adverse health effects due to UV radiation. (6) Recognition that CFCs do not impact tropospheric ozone. Figure 2. Student performance on pre-, post-, and final assessments with respect to atmospheric environmental chemistry concepts.

Discussion Overall, the students made some individual gains in understanding of global warming, ozone depletion, and smog formation as a result of the electronic data-analysis materials. Students improved their ability to recognize the components contributing to and effects associated with global warming, ozone depletion, and smog formation, but a large number of students remained confused about the mechanisms involved. The magnitude of the gains from the electronic exercises alone was moderate (roughly 10–20%) and, unfortunately, many students continued to believe that ozone depletion was the cause of global warming. In hindsight, it would appear that the computer exercises were strong on the data-analysis aspect and helped students to identify important trends in atmospheric chemistry, but they did not sufficiently address the relationship (or lack thereof ) between global warming and ozone depletion. Although the electronic materials did not perform as well as we had hoped, we do not conclude that the online exercises were a failure. Many investigators have shown that students are extremely resistant to abandoning their misconceptions and that constructing new scientific understanding is a very intensive process (12–14). Students showed great improvement on the final assessment once the electronic exercises were supported with lecture information and smallgroup discussions. This suggests that the online exercises alone were not sufficient to displace the targeted misconceptions. Integration of individual online learning, group discussion,

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Material

All materials for the data-analysis exercises are available in this issue of JCE Online and can be accessed online at http://ceret.us/ceret/projects/delta-program/ACnstrucMaterials/ default.shtm. Literature Cited 1. Swan, J. A.; Spiro, T. G. J. Chem. Educ. 1995, 72, 967–968. 2. Toby, S. J. Chem. Educ. 1997, 74, 1285. 3. Khalid, T. Environ. Educ. Res. 2003, 9, 35–50.


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Research: Science and Education 4. Cordero, E. C. Aust. Sci. Teach. J. 2002, 48, 34–39. 5. Jeffries, H.; Stanisstreet, M.; Boyes, E. Res. Sci. Technol. Educ. 2001, 19, 205–221. 6. Boyes, E.; et al. Environ. Educ. Res. 1995, 1, 133–149. 7. Keeling, C. D.; Whorf, T. P. Atmospheric CO2 Records from Sites in the SIO Air Sampling Network. In Trends: A Compendium of Data on Global Change; Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy: Oak Ridge, TN, 2005. 8. Petit, J. R.; Raynaud, D.; Lorius, C.; Jouzel, J.; Delaygue, G.; Barkov, N. I.; Kotlyakov, V. M. Historical Isotopic Temperature Record from the Vostok Ice Core. In Trends: A Compendium of Data on Global Change; Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy: Oak Ridge, TN, 2000. 9. Barnola, J.-M.; Raynaud, D.; Lorius, C.; Barkov, N. I. Historical CO2 Record from the Vostok Ice Core. In Trends: A Compendium of Data on Global Change; Carbon Dioxide In-

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formation Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy: Oak Ridge, TN, 2003. Shanklin, J. D. British Antarctic Survey Ozone. http://www. antarctica.ac.uk/met/jds/ozone/index.html (accessed Jul 2007). Dinsmore, D. Wisconsin Department of Natural Resources. Madison, WI, Unpublished work, 2005. Mulford, D. R.; Robinson, W. R. J. Chem. Educ. 2002, 79, 739. Huddle, P. A.; White, M. D.; Rogers, F. J. Chem. Educ. 2000, 77, 104. Herron, J. D.; Nurrenbern, S. C. J. Chem. Educ. 1999, 76, 1353. Climate Ark: Climate Change Overview. http:// www.climateark.org/overview (assessed Jul 2007). The Ozone Tour Home Page. http://www.atm.ch.cam.ac.uk/ tour/index.html (assessed Jul 2007). TravelMatters Individual Emmission Calculator. http:// www.travelmatters.org/calculator/individual (assessed Jul 2007).


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"Holes" in Student Understanding: Addressing Prevalent

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