INTRODUCTIONIn the last two hundred years, the activities of

human beings have an increasing detrimental effecton earth. Because of the life style of the humanbeing several major environmental problems haveemerged, environmental sources have been depletedwastefully, the natural habitats of many species havebeen destroyed, and as a consequence, many specieshave become extinct.

As global warming, ozone layer depletion is one

of the most serious global environmental problemsas it is a threat to our biosphere with enormousenvironmental, health and economic consequences.Declining levels of stratospheric ozone resultingfrom anthropogenic source gases such aschlorofluorocarbons (CFCs) are internationallyrecognized. In the last twenty years, global ozonetrends show that concentrations are decreasing by 2-5% per decade in the middle latitudes. The societalconcern is that with decreasing concentrations of

Received: 13.01.2008/ Accepted: 29.03.2008

Mehmet BAHAR1*, Hüseyin BAÐ2, Orçun BOZKURT3

1Abant Izzet Baysal University, Faculty of Education, Department of Science Education,Bolu-TURKEY2Pamukkale University, Faculty of Education, Department of Science Education,Denizli-TURKEY3Mustafa Kemal University, Faculty of Education, Department of Science Education,Hatay-TURKEY

*Corresponding author: mehmet.bahar@gmail.com

Pre-Service Science Teachers' Understandings of anEnvironmental Issue: Ozone Layer Depletion

AbstractThe purpose of this study is to determine pre-service science teachers' misconceptions, knowledge level andthe ways of gaining knowledge in relation to ozone layer and ozone layer depletion, which is one of theglobal environmental problems. In order to get relevant data, the questionnaire comprising 30 items on afive point Likert type scale and seven multiple choice questions were administered to 308 pre-servicescience teachers. Statistical procedures were performed in order to interpret the data obtained through thequestionnaires. The findings revealed that the pre-service science teachers participated in the study haveinsufficient knowledge as well misconceptions regarding ozone layer depletion. In addition, it was alsofound out that they had the information about the ozone layer not only through formal education but alsothrough other sources such as media, peers etc. The differences and similarities of the results compared tothe other research studies are emphasized and implications of the results for deeper understanding as wellas for better teaching are discussed.Keywords: Environment, misconceptions, ozone layer, pre-service science teacher.

Fen Öðretmeni Adaylarýnýn Bir Çevresel Konuyu Anlamasý: Ozon Tabakasýnýn Ýncelmesi ÖzetBu çalýþmanýn amacý küresel çevre sorunlarýndan birisi olan ozon tabakasý ve onun incelmesi ile ilgili olaraköðretmen adaylarýnýn bilgi düzeylerini, kavram yanýlgýlarýný ve bilgi edinme yollarýný belirlemektir. Buamaçla beþli likert ölçeðinde otuz madde ve yedi çoktan seçmeli soru içeren bir anket formu 308 fenöðretmeni adayýna uygulanmýþtýr. Anketten elde edilen verilerin yorumlanabilmesi amacýyla istatikseliþlemler yapýlmýþtýr. Sonuçlar, fen öðretmeni adaylarýnýn ozon tabakasýnýn incelmesi konusunda hem yeterlidüzeyde bilgiye sahip olmadýklarýný, hem de kavram yanýlgýlarýna sahip olduðunu göstermiþtir. Sonuçlarayrýca fen öðretmeni adaylarýnýn ozonla ilgili sadece okulda aldýklarý eðitimle deðil, basýn-yayýn, arkadaþgrubu vb. diðer kaynaklardan da beslendiðini ortaya koymaktadýr. Bu araþtýrmada elde edilen sonuçlarýndiðer çalýþma sonuçlarý ile karþýlaþtýrýldýðýnda ortaya çýkan farklýlýk ve benzerlikler vurgulanmýþ, sonuçlarýndaha derin bir öðrenme ve daha iyi bir öðretme için anlamý tartýþýlmýþtýr.Anahtar kelimeler: Çevre, fen öðretmeni adayý, kavram yanýlgýsý, ozon tabakasý.

Bahar M, Bað H, Bozkurt O (2008) Pre-Service Science Teachers' Understandings of an EnvironmentalIssue: Ozone Layer Depletion. Ekoloji 18, 69, 51-58.

Ekoloji 18, 69, 51-58 (2008)

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ozone, the amount of the Sun's UV radiationreaching the Earth's surface will increase andpotentially damage both human and other biologicallife (Cordero 2001). As asserted by Dove (1996),discovery of the hole in the ozone layer overAntarctica and an increase in the incidence of skincancer (any other diseases such as cataract, sunburn,affection of human immune system etc) caused thepeople turn their attention to ozone layer depletion.

After dramatic increase in environmentalproblems public especially in developed countriesstarted to pay systematic attention to the interactionbetween man and the environment, the causes ofenvironmental problems, or potential solutions. As aresult, the importance of the environmentaleducation have been emphasized to developinformed and skilled citizens who are willing andable to take action to resolve environmental issuesand understand the importance of maintaining ahealthy balance between the quality of life and thequality of the environment (Hungerford et al. 1980,Toili 2007). Consequently, environmental educationhave been integrated into the school curriculum ortaught as a separate course to donate students havingnecessary environmental knowledge, showingenvironmentally responsible behavior and attitudes.In spite of this increasing attention many researchstudy results, as mentioned below, show thatstudents as well as teachers may have insufficientknowledge and/or misconceptions concerningglobal environmental issues. It is true that whenindividuals see the occurrence of various naturalphenomena they make attempts to find thereasoning for them using their knowledge andintuition (Gallegos et al. 1994). As a result, theydevelop certain perceptions of the naturalphenomena. However, these perceptions might notbe in consisted with the scientific explanation. Moreinterestingly, these perceptions (or intuitive ideas)about several phenomena including ozone layerdepletion might be preserved by the student evenafter formal instruction.

Misconceptions regarding ozone layerdepletion: In general terms misconceptions can bedescribed as the students' intuitive ideas or naiveconcepts that are scientifically are incorrect. For themisconceptions that are inconsistent with scientificknowledge even after teaching are also useddifferent terms such as alternative frameworks(Driver et al. 1985) or alternative conceptions

(Gilbert and Swift 1985) etc. Unfortunately, as seenin other topics (e.g., acid rain, global warming etc),pupils in primary and secondary schools as well asuniversity students have particular misconceptionsassociated with ozone layer depletion. In severalstudies were pointed out that many studentsbelieved that ozone layer depletion is a major causeof global warming and the hole in the ozone layerallows a greater penetration of sunlight that result inraising the temperature of the earth (Rye et al. 1997,Toili 2007). These misconceptions are strongly heldand persist to change despite media publicity andinclusion of the issues related ozone layer depletionand global warming in the formal curriculum(Jeffries et al. 2001). By using concept maps as amental model Rebich and Gautier (2005) foundevidence of the flawed mental model that attributesincreasing global temperature to increasing solarinput trough the ozone hole. The results of thesurvey of first year students in Australia also showedthat majority of the students has twomisconceptions; the ozone hole resides overAustralia and ozone depletion is the major cause ofAustralia's high rate of skin cancer (Cordero 2001).In a recent study done by Pekel and Ozay (2005) inTurkey with 177 rural high school students showedthat even though most of the students seem wellinformed about the nature of the ozone layer, manystudents possess some misconceptions related toozone layer damage, its causes and consequences. Intheir study few students realized that gases releasedby volcanic eruption can reduce the concentrationof stratospheric ozone whereas many recognizedthat radioactivity, gases from the fridges and plastics,rainforest destructions and acid rains could. Thus,many of them thought that ozone depletion wouldexacerbate the greenhouse effect and, perhaps as aconsequence increase flooding and hearth attacks,danger to marine organisms, unsafe water supplies,or air escaping to the space.

In the literature, there are limited studies relatedto the misconceptions or/and insufficientknowledge of teacher or teacher candidates withregard to the global environmental issues such asozone layer depletion, global warming and acid rainetc. (Summers et al. 2000, Khalid 2003,Papadimitriou 2004). By using in depth interviewswith a sample of 12 primary school teachers,Summers et al. (2000) reported some missingconcepts and misconceptions that similar to those

mentioned above paragraph related to ozone layerdepletion. In Khalid's (2003), study pre-service highschool teachers showed misconceptions when theytry to interconnect the two apparently independentphenomena of the greenhouse effect and ozonedepletion in the upper atmosphere. Somemisconceptions that they possess are as follows: i)holes in the ozone allow more radiation to the earththat increase the green house effect, ii) increasedgreenhouse effect will destroy the ozone and therewill be more radiation, which will increase theincidence of skin cancer and iii) carbon dioxidefrom car emissions and carbon monoxide breakdown the ozone in the upper atmosphere.Papadimitriou (2004) revealed in his study thatstudent teachers confused greenhouse effect withozone depletion as far as the mechanisms throughwhich they occur are concerned and casualcompounds. Majority expressed that a hole or ofmany holes in the ozone layer exist. Some of themthought that ozone layer consists of manycompounds; the hole in the ozone layer makes thesun rays become vertical and the pollutants justdissolve ozone, which disappears. In addition,significant percentage name carbon dioxide as acompound connected to the ozone destruction.

Based on the findings studies mentioned above,it might be said that students as well as teachers inservice or/and pre-service teacher do not possess thesame misconceptions. However, they have similarmisconceptions and/or insufficient knowledgeregarding ozone layer depletion even in the differentcountries.

It might be plausible to assume that pupils'understanding of several aspects of environmentalissues can be valuable source for teachers as well asfor curriculum developers so that teachers can teachmore effectively and curriculum developers mayarrange the content to prevent the misconceptions.Thus the determination of in-service or pre-serviceteachers' misconceptions about manyenvironmental issues, ozone layer depletionincluded, may help the teachers to acquire deeperand better understanding of the subject so that theycan be aware of the misconceptions and teach thesubjects properly. Also, determining pre-knowledgeand misconceptions of teacher candidates on theseenvironmental issues ozone layer depletion inparticular, overcoming the misconceptions andconstructing the basic network of meaningful ideas

in the mind correctly would be important andmeaningful. Emerging field of environmentaleducation reflecting this understanding mightprovide contribution for people to solve the localand global environmental problem. This studyaimed i) to determine the knowledge level andmisconceptions of pre-service science teachers whowill have great role in teaching environmental topicseffectively and also ii) to find out the ways of gainingtheir knowledge related to ozone layer and ozonelayer depletion, which is one of the globalenvironmental problems.

MATERIAL AND METHODSample of the study: Present study was carried

out with 308 (203 female, 105 male) pre-servicescience teachers enrolled in Department of ScienceEducation in Turkey (Gazi and PamukkaleUniversity) during 2005-2006 academic year. Theparticipants were from different grades. Table 1summarizes the demographic characteristics ofparticipants.

Data collection instrument and process: Inorder to determine misconceptions of pre-servicescience teachers in relation to ozone layer, theinstrument developed by Boyes and Stanisstreet(1999) was used. This instrument was translatedinto Turkish and the reliability of the test wasestablished by Bozkurt et al. (2006). The instrumentadministered includes 30 items on a five point Likerttype scale (5-I am sure this is right, 1 - I am sure thisis wrong) and seven multiple choice questions withfive alternatives. The first sets of the questions (tenitems) are related to the results of ozone depletion.The second set (following ten items) focuses on thecauses of ozone depletion and the third set ofquestions (the last ten items) are regarded as theways to lessen ozone depletion. The multiple choicequestions targeted factual questions (five items) andopinion questions (two items). Under each multiplechoice questions, spaces were provided forparticipants to present explanations for theirresponses. In addition to these items in thequestionnaire participants were also asked about thesources that they may have their information relatedto ozone layer. The numbers of the item and aim ofeach sub-set of the questionnaire are given in Table2.

The instruments were administered to theparticipants during 2005-2006 academic year in classsetting. Administration lasted approximately 20-25

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minutes. Data Analysis: The data collected firstly

compiled and then the likert type items wereentered into the SPSS file created, and analyzed bymeans of frequency and percentage values. With thedata obtained and analyzed by using mean values,percentages and frequencies, pre-service scienceteachers' knowledge level and misconceptionsrelated to ozone layer. The findings weresummarized in tables.

RESULTS Pre-service science teachers' responses given to

each subset of questionnaire showed wide variation.Total mean scores of each subset were quite low. Asmall part of the participants in the study respondedcorrectly to the items in the questionnaire.However, most of them failed. The items that werecorrectly answered by high number of students arerelated to causal relationship on ozone layerdepletion. Table 3, 4, 5 and 6 summarizes correctanswers given to each items under three subsets andmultiple choice items. As it can be seen from theTable 3, most of the students had wrongunderstanding on results of the ozone layerproblems. For example, pre-service science teachersdid not believe that occurring air pollution andwater pollution, shrinking in volume of iceberg,flooding, being unsafe of tap water and gettinghotter weather are not results of ozone layerproblem. It can be said that students haveconsiderable misconceptions related to the results ofozone layer depletion. Items numbered as 1, 3, 7 and8 are related to global warming (the effects of CO2).However, the participants did not perceive globalwarming as a result of ozone layer problem. In thisrespect, they were only aware of changes in theworld's water as a result of ozone layer depletion.

As indicated in Table 4, the pre-service teachersgenerally believed that the ozone layer is depletedand is getting worse as a result of radioactive waste(84.4%), use of certain pesticides (78.6%), gasesemitted from artificial fertilizers (75%), and man-made CFC gases entering the atmosphere (67.5%).So, according to the pre-service science teachers,these are main factors causing ozone layer depletion.However, most of them did not think that too muchsunlight reaching the earth surface, too much CO2

entering atmosphere, too much UV reaching theearth surface, gases from rotting waste, acid, andsunlight reflected do not bring rise to ozone layer

depletion.As pointed out by the results of third subset (in

Table 5), pre-service science students believed that,in order to lessen the ozone layer depletion,unleaded gases should be used, the use of CFC gasesand certain pesticides should be stopped. By doingthese, ozone layer depletion, as claimed by students,might be lessened. On the other hand, they did notknow the roles of planting trees, and recyclinghousehold trash in dealing with ozone layerdepletion. Further, they confused about the role ofCO2 and methane that cause ozone layer problems.

Looking at correct responses given to themultiple choice items, few students failed on factualknowledge in relation to ozone layer. They hadmisconception on thickness of ozone layer as well asthe size of the ozone layer. It can be said that mostof the students believed that its thickness is about 11

Table 2. Numbers of the item and aims of sub-sets.

Table 1. Demographic characteristics of participants.

Table 3. Correct answers given to the items under first subset of questionnaire.

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km. Also, their responses to the size of ozone holesvaried. About half of the participants knew thelocation of ozone layer (46.4%), the composition ofthe ozone layer (41.9%) (in Table 6). They believedthat the ozone layer depletion is real, not political.

In terms of the preservice science teachers' theinformation source related to the ozone layer, theirresponses showed that they obtained theinformation about ozone layer from differentsources. The information source that they got mostof their knowledge on ozone layer was media (TV,magazine journal and radio). Other sourcescontributing to knowledge acquisition on ozonelayer were their previous teachers, their friends (orpeers), books, academic staff and expert onenvironmental studies respectively.

DISCUSSIONS AND SUGGESTIONSThe responses given by pre-service science

teachers to questionnaire dealing with ozone layerand ozone layer problems indicated that theypossess general knowledge in relation to this issue.However, at the same time, considerable numbersof them have misconceptions and/or insufficientknowledge on ozone layer and ozone layerdepletion. They also seem to confuse the ozonelayer depletion with global warming. These findingsare somewhat parallel to findings of research studiescarried out by several researchers in the primary andsecondary school levels (Francis et al. 1993, Boyesand Chambers 1995, Somerville 1996, Rye et al.1997, Meadows and Weisenmayer 1999, Jeffries etal. 2001, Toili 2007) as well as shows parallelism tothe findings of the research studies (Groves andPugh 1999, Summers et al. 2000, Khalid 2003,Papadimitriou 2004) done with pre-service scienceteachers. It is interesting to see similarmisconceptions and/or insufficient knowledgerelated to ozone layer depletion in the students andpre-service teachers from different countries. Thismight support the claims that the misconceptions(or alternative conceptions) that learners bring toformal science instruction cut a cross culturalboundary (Wandersee et al. 1994). In other words,students' or teachers' naïve descriptive andexplanatory systems may show consistency acrossdiverse population irrespective of nationality.

The finding of research studies done by Pekeland Ozay (2005) is particularly important for thisstudy results. Although they administrated theirstudy in the schools of rural areas in Turkey some of

the misconceptions and/or insufficient knowledge(such as ozone depletion would exacerbate thegreenhouse effect and, perhaps as a consequenceincrease flooding etc) that students between the ageof 16 and 18 possess in secondary schools may seemto present in the head of pre-service scienceteachers. These may support the idea thatmisconceptions are strongly held and persist tochange despite media publicity and inclusion in theformal curriculum (Jeffries et al. 2001, Pekel andOzay 2005). With regard to this statement it isimportant to answer the question 'why are themisconceptions resistant to change?' One of the

Table 4. Correct answers given to the items under second subset of questionnaire.

Table 6. Correct answers given to the multiple choice items.

Table 5. Correct answers given to the items under third subset of questionnaire.

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answers can be related with the teaching strategies.Wandersee et al. (1994) state that misconceptions aretenacious and resistant to extinction by conventionalteaching (i.e. teacher centered) strategies. Asindicated in some studies done in other countries(Pekel and Ozay 2005, Toili 2007) in the majority ofthe schools and in the universities in Turkeyteachers and lecturers use mainly teacher-centeredstrategies that promote memorization andreproduction of the knowledge on the day ofexamination where the multiple choice is mainlyused. Whereas in order to avoid misconceptions orto change misconceptions especially in the topicozone layer depletion that is abstract in naturestudent-centered teaching strategies should be usedso that student can be mentally and physicallyengaged to avoid misconceptions or to changemisconceptions especially in the subject ozone layerdepletion that is abstract in nature. By doing this,students may have a chance for being aware of theirmisconceptions and challenging of them for deeperand meaningful understanding. Using technologymay help for these purposes. Technologicalapplications as using hypermedia and virtual realitytechniques may offer more great promise in the areaof providing challenging, conflict-inducingenvironments that would far exceed the ability of atext to alter perceptions related to ozone depletion aswell as global environmental problems.

It is important to mention that the curricula inTurkish education system including science andtechnology for primary schools and biology inparticular for secondary schools have been recentlydeveloped in the light of constructivist approach inwhich active engagement of the students (student-centered) in all activities are emphasized. By takingthe account of the research findings and some otherfactors, the environmental issues have been infusedin to the science and technology curriculum inprimary school and particularly in biologycurriculum to the all levels. This approach may helpto prevent occurring misconceptions as well as toremedy the ones that students already possess.

In general it can also be said that ozone depletionis a relevant interdisciplinary science issue thatincorporates fundamental topics in biology,chemistry, meteorology and physics and cancombine science topics with facets related to politicssocial culture and economics. Therefore like otherglobal environmental issues ozone depletion may

offer an excellent teaching opportunity to see allthese disciplines as a meaningful network. Inaddition, it may help to understand our position as aenvironmentally conscientious individual locally aswell as globally so that a better environment mightbe left to the future generations.

As claimed by Khalid (2003), a big part of societycan acquire fundamental environmentalinformation through mass media such as magazinejournal, radio and television. However, inaccuraciesin the reporting of important environmental issuesincluding ozone layer depletion through media mayconfuse issues that are already complex andmisunderstood (Cordero 2001). Similar to theseclaims, pre-service science teachers participated inthis study reported on the ways of gaininginformation about ozone layer and ozone layerdepletion that media really contributed to getfundamental information in relation to these issues.It is interesting to notice that most of theparticipants can get information through mediarather than their education. In this sense, it is clearthat the insufficient and wrong information gotthrough these sources might make the adultsconstruct misconceptions in relation to ozone layer(Boyes and Stanisstreet 1997).

The constructivist view is that knowledge has tobe reconstructed as it passes from one personanother. Learning is not the transfer of knowledgefrom the head of teacher to the head of studentintact. Therefore the students must reconstructknowledge into their own terms and understanding(Johnstone et al. 2000). In this case, language andthe meaning of the terms should play an importantrole in this process. One of the reasons behind ofmisconceptions related to ozone layer depletionmight also be caused by the meaning of terms "layer"and "holes" itself. In daily life using the term "layer"can give people an idea that ozone in the atmosphereis a thin layer or a sheet like covering around theearth. In fact, it is a rare gas, which is spread in thestratospheric region among other gases such asnitrogen. It makes up only a small component ofgases in that region where its concentration is just afew particles per one million particles of air(Somerville 1996, Toili 2007). The term "hole" alsomay cause similar problems as the term "layer".There is a continuous process of destruction andreconstruction of ozone molecules going on in thestratospheric region (Somerville 1996) and the hole,

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in fact, may not truly reflect the meaning of thereduction of the ozone molecules concentration.Because the meaning of terms can be different ineveryday context and in scientific context, it is littlewonders that students can lay hold of completely

wrong ideas or misconceptions. In light of of allthese findings and comments related to language, itcan be said that the teachers and textbook writersshould be careful about the language andterminology they use.

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