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“A statistically manifested teaching concept about air,greenhouse effect, ozone and acid rain for major college students"

Nina HARSCH, Hans-Dieter BARKE

Institute for Chemistry Didactics, Fliednerstraße 21, 48149 Münster, GermanyE-mail: [email protected]

Phone: 0049-251-8339467Fax: 0049-251-8338313

AbstractNowadays, atmospheric pollution is a current topic which also concerns adolescents and their future. Therefore, they should know how to explain global phenomena such as the anthropogenic greenhouse effect, the ozone hole and ozone smog, as well as acid rain (which is still an actual problem e.g. in China). As the understanding of these topics requires a significant amount of chemical knowledge, chemistry class is the perfect environment for their acquisition. Nevertheless, as these topics are interdisciplinary, they could also be incorporated into other natural science classes.Asking adolescents about their understanding of chemical topics, misconceptions are a common problem. In this context, a survey with approximately 1.500 tenth and twelfth grade students from Germany, Spain, Taiwan and Russia was conducted. Particular emphasis was put on the technical knowledge, possible misconceptions and the attitude of the participants towards environmental protection. “All air pollutants are greenhouse gases.” - “The greenhouse effect is caused by the ozone hole.” - “Acid rain provokes chemical burn and cancer.”… Those and other misconceptions, amongst a significant general lack of knowledge, were discovered by this survey.Based on these findings, a lecture series was developed and tested in chemistry class on German secondary school level students throughout a period of nine lessons. The learning progress was documented via pre-, intermediate- and post-tests. Comparing the positive results of the lecture series with the lack of knowledge of other (even older) students, the necessity of the official incorporation of these globally relevant topics in class becomes evident.

Keywords: Greenhouse effect, ozone, acid rain, senior college students, empirical study, lecture series

1. IntroductionEver since the industrial revolution and its economical and social benefits, humanity has also been forced to cope with the environmental consequences of such vast growth and sustained development. Globally relevant atmospheric phenomena, such as acid rain, acid winter smog, ozoniferous summer smog, the destruction of the ozone layer, the anthropogenic greenhouse effect and climate change, have taken their permanent place in natural science research, as well as in the media and in everyday life discussions. Nevertheless, in Germany as well as in many other countries, there still is a lack of proper implementation of these topics into college education. Reasons for this might be their interdisciplinary character (most often, they involve chemical, physical, biological and geographical aspects) on the one hand, and the current “teach more in less time” politics, leaving little room for any off-beat content, on the other hand. Within the ongoing global climate change discussion, it is overlooked that young people are the ones who will have to deal with the consequences and thus imperatively need a solid knowledge base regarding atmospheric phenomena. In order to illustrate mankind´s power to really make a change, this should incorporate both current topics such as the greenhouse effect, and technically solved problems such as acid rain and the ozone hole.Due to these reasons, an international empirical survey among 1.500 college students of grade 10 and 12 was conducted in order to evaluate the knowledge level and the possible misconceptions of the students concerning air, acid rain, ozone and the greenhouse effect1. Based on the findings of these survey, as well

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as on literature research and expert consultations, a nine-hour lecture series was developed and applied in several classes. The structure and main results of both the survey and the lecture series will be succinctly presented in this paper.

2. Empirical StudyAs mentioned above, the first part of this research project comprises an empirical survey about air and atmospheric pollution.

2.1 Questionnaire and Target GroupThe questionnaire applied in order to investigate the students´ knowledge and misconceptions about air and atmospheric pollution contains four subject areas:(a) Air: Atmospheric composition, differentiation of trace gases and air pollutants(b) GE: Definition of greenhouse gases, causes and consequences of the GE(c) OZ: Formation and destruction of stratospheric and tropospheric OZ, countermeasures(d) AR: Naturally and humanly caused AR, gas sources, countermeasuresRegarding the target group, due to the chemical complexity of the subject areas, the questionnaire was given to major students only, that is, grade 10 and, to have a cross-sectional comparison, also grade 12, of all common school types. In order to furthermore obtain a international comparison, the survey was conducted in several countries, specifically Germany, Spain, Russia and Taiwan.

2.2 Principal Findings of the Empirical StudyAlmost regardless of age and country, the evaluation of the survey revealed a significant lack of knowledge, as well as several misconceptions throughout all four subject areas. The most important findings will be presented in the following. In order to give a total overview, the percentages always refer to the entire student population (that is, grade 10 and 12 together). More detailed results, incorporating age and country differences, can be found in [1].Asking the students about the main air components, 78 % nitrogen and 21 % oxygen, only a mere 20 % of the students were able to give the correct reply, while most of the others over-estimated the carbon dioxide rate and/or sub-estimated the nitrogen rate. Looking at the minor air components and letting the students describe their notions of trace gases, air pollutants and greenhouse gases, it becomes clear that most of them don´t differentiate between these three terms. Hence, to many of the students „all trace gases are air pollutants“ and „all air pollutants are greenhouse gases“.Concerning the greenhouse effect, a 30 % of the surveyed pupils were able to give a correct description of how the GE works. When asked about the most significant greenhouse gases, only a mere 28 % of the pupils mentioned water vapour. Thus, it can be deduced that most of the students regard the GE to be completely anthropogenic (caused by humanity). Another very important misconception which can be found in the majority of the students consists in stating an interdependency between the GE and the ozone hole. To many of the students „the greenhouse effect causes the ozone hole“ or „the ozone hole causes the greenhouse effect“.The topic „ozone“ (which incorporates both stratospheric and tropospheric ozone) showed low values for the recognition of tropospheric (ground level) OZ, which was known by only 21 % of the students. Stratospheric OZ, however, received better results, with a 44 % of the pupils naming the correct geographic location of the ozone hole (Antarctica) and again 44 % mentioning CFCs as a major factor for the depletion of stratospheric OZ. On the whole, it may be stated that for many students „ozone exists only in the ozone layer“. Furthermore, for those who did not know about the ozone hole above Antarctica, „the ozone hole is located above the industrial countries“, that is, above the countries with the highest emission rates. ______________________________1. As from now, the following abbreviations apply: GE: Greenhouse Effect OZ: Ozone (stratospheric and tropospheric) AR: Acid Rain


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The last part of the survey treated with acid rain. Here, the findings were that a 55 % of the pupils knew sulphur dioxide and nitrogen dioxide to cause AR, a 44 % furthermore correctly mentioned carbon dioxide and a 35 % were able to name some consequences of AR (e.g. deterioration of monuments, damage to forests, acidification of lakes). Regarding misconceptions, it can be deduced that those pupils who did not mention carbon dioxide, might be of the opinion that “acid rain is completely anthropogenic”. Apart from that, some of the students believe that “acid rain is concentrated acid”.

3. Lecture SeriesThe second part of this research project comprises the conception and application of a lecture series about air and atmospheric pollution. Regarding the conception, the results of the above described empirical study, as well as extensive literature research and expert interviews were accounted for.

3.1 Conceptual DesignThe conception of the lecture series comprised three working stages.The first stage consisted in analyzing the knowledge level and the possible misconceptions of the target group concerning air, GE, OZ and AR. This was done via the empirical study described in chapter 2 of this paper. These results were furthermore compared to already published findings in literature. As a second step, extensive literature research was done concerning already existent teaching concepts about these topics. Out of this, possible didactical approaches were developed and then discussed with experts (such as teachers and scientists).Stage 2 represents the result of the discussed didactical approaches and can be seen as a pilot concept of the lecture series. This pilot concept is composed of 7 school lessons which are surrounded by a pre- and a post-test and can be divided into three parts: First, the students take three lessons to acquire basic knowledge about the 4 subtopics air, GE, OZ and AR by means of expert learning.2 Then, the teacher uses one lesson to introduce a concept map in order to both recapitulate the basics and point out thematic interrelations. And finally, there are three lessons of teacher-class dialogue and experiments incorporating further knowledge about GE, OZ and AR.Stage 3 is the final, optimized teaching concept which is based upon the findings and eradicated weaknesses of the pilot concept. The three main weaknesses of the latter were:

(a) The expert learning was too hard for weak students.

(b) The topic “air” did not include any experiments and (thus) showed poor learning results.

(c) The permanent topic rotation appeared to be confusing to the students.

Due to these findings, the pilot teaching concept had to be revised. The optimized concept therefore is structured as follows:

- Lesson 1: Teacher-class dialogue and experiments about the main air components. Definition and differentiation of trace gases and air pollutants.

- Lessons 2-4: Group learning.3 Three groups with one topic each (GE, OZ, AR).

- Lessons 5-7: Each group presents their topic, including an experiment about it.

- Lessons 8-9: The teacher introduces a concept map in order to both recapitulate the basic knowledge and point out thematic interrelations.

______________________________2. Expert learning: Pupils are distributed into different thematic groups and then pass through the following stages: (a) individual studying, (b) exchange between experts, (c) each expert transmits their knowledge to their peer group. In this way, each pupil learns about each topic.3. Group learning: Pupils are distributed into different thematic groups and then pass through the following stages: (a) group studying, (b) preparation of presentations, (c) each group presents their topic to the remaining students. In this way, each pupil learns about each topic.


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3.2 Main Results of the Lecture SeriesThe main learning results of the pilot concept are shown in Figure 1 and Figure 2.

Figure 1 Pilot lecture series - pre-test vs. post-test

Figure 2 Pilot lecture series - post-test vs. independent test

Figure 1 shows the knowledge level of the pre-test in comparison with the post-test results. The improvement rates were 12 % for air, 20 % for GE, 29 % for OZ and 34 % for AR. On the hole, the pre-knowledge level was 43 % and the post-knowledge level was 67 %, which makes a general performance improvement of 24 %.Figure 2 shows the knowledge level of an independent test (= pupils not taking part in the lecture series) of grade 12 in comparison with the post-test results (grade 10). Despite their younger age, the grade 10 students performed better than the ones of grade 12. The rate differences were 1 % for air, 25 % for GE, 25 % for OZ and 29 % for AR. On the hole, the knowledge level of the grade 12 students was 47 % and


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the (post-)knowledge level of the grade 10 students was 67 %, which makes a 20 % higher general performance of the latter.

Figure 3 Pilot concept vs. optimized concept: comparative increment of achievements

Figure 3 shows the differences in improvement comparing the relative pre-post-difference of the most important items of the pilot concept with the optimized concept. For air and OZ, the optimized concept shows better results than the pilot concept. Regarding GE and AR, the pilot concept shows slightly better results for some items. Nevertheless, on the whole, the optimized concept achievements are significantly higher than those of the pilot concept.

4. ConclusionsThe topic „air and atmospheric pollution“ is demanding and due to the complexity of the subject area, there is still room for further improvement of the lecture series. A survey amongst teachers showed their interest in the incorporation of the lecture series in their class, which is an important premise for its implementation. In order to assure the quality of the tuition, teachers´ trainings are very important.

5. Reference list[1] N. Harsch, C. Estay, H.-D. Barke, Praxis der Naturwissenschaften - Themenheft Schüler(fehl)vorstellungen als Chance,

2011, 3/60, 20-25.


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