The effect of case-based instruction on 10th grade students' understanding of gas concepts

This journal is©The Royal Society of Chemistry 2014 Chem. Educ. Res. Pract.

Cite this:DOI: 10.1039/c4rp00156g

The effect of case-based instruction on 10thgrade students’ understanding of gas concepts

Eylem Yalcınkayaa and Yezdan Boz*b

The main purpose of the present study was to investigate the effect of case-based instruction on

remedying 10th grade students’ alternative conceptions related to gas concepts. 128 tenth grade students

from two high schools participated in this study. In each school, one of the classes was randomly assigned

as the experimental group and the other class, instructed by the same chemistry teacher, was assigned as

the control group. The students in the experimental groups were instructed by case-based instruction

based on conceptual change conditions while the control group students received traditionally designed

chemistry instruction. As pre-tests, the science process skills test, the attitude and motivation towards

chemistry and the gas concept test were applied to both groups of students. As a post-test, the gas

concept test was administered to both groups of students to determine their alternative conceptions and

understanding of gas concepts. One-way ANOVA was used to assess the effect of case-based instruction

on students’ understanding of gas concepts. The results revealed that case-based instruction was an

effective method for overcoming students’ alternative conceptions about the gas concepts.

Introduction

Constructivism explains learning as an active process, wherestudents construct their own knowledge by making links betweentheir existing and new concepts. In the case of a contradictionbetween new knowledge and existing ideas, it is hard to makesense of it since learners cannot make meaningful connections.This indicates that a person’s prior knowledge plays a critical rolein the process of learning (Driscoll, 2005). Research studies onscience learning indicated that students come to classes with theirown conceptions, which are often different from the scientificallyaccepted view. These alternative conceptions hinder students’subsequent learning since they interpret new knowledge in thelight of these alternative conceptions (Gilbert et al., 1982). There-fore, instruction that considers students’ prior knowledge andthat allows students to modify their conceptions of scientific ideaswould be beneficial to remedy students’ alternative conceptions.As Wassermann (1994) states, case-based instruction serves thispurpose by embedding learning in a realistic and social environ-ment where students are actively involved in the process ofknowledge construction. Although case-based instruction hasbeen used in medicine, law, and business, there have been fewresearch studies in science education. Moreover, there is almost

no reported research study investigating the effectiveness ofcase-based instruction for overcoming students’ alternativeconceptions about the gas concepts. The present study aimsto contribute to the literature by finding out whether case-basedinstruction is effective in enhancing students’ understanding ofgases and remedying their alternative conceptions. The relatedresearch questions are;

1. Is there a significant mean difference between the groupsexposed to case-based instruction based on conceptual changeconditions and traditionally designed chemistry instructionwith respect to tenth grade students’ understanding of gasconcepts and alternative conceptions?

2. What are the tenth grade students’ alternative conceptionsabout gases after being exposed to case-based and traditionalinstruction?

Literature review

Most of the studies in science education indicated that students atall levels have difficulty in understanding the basic properties andbehavior of gases (Novick and Nussbaum, 1978, 1981; Ben-Zviet al., 1982; Brook et al., 1984, 2003; Gabel et al., 1987; Stavy, 1988;Benson et al., 1993; Hwang, 1995). For example, research studiesshowed that students face problems in understanding the notionof empty space between particles. Students stated that dust, otherparticles, gases such as oxygen and nitrogen, air, dirt, unknownvapors exist between particles (Novick and Nussbaum, 1978, 1981).In addition, students thought that gases have no mass or that

a Tunceli University, Faculty of Engineering, Department of Chemical Engineering,

Tunceli, Turkeyb Middle East Technical University – Faculty of Education, METU Universiteler Mah.

Dumlupınar Blv. No:1, Ankara cankaya 06800, Turkey.

E-mail: [email protected]

Received 22nd July 2014,Accepted 28th October 2014

DOI: 10.1039/c4rp00156g

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substances in the gas phase are lighter than in the liquid or solidstate (Stavy, 1988, 1990; Mas et al., 1987; Lee et al., 1993). Anothercommon misconception is that students attribute macroscopicproperties to particles, such as ‘‘expand’’ and ‘‘contract’’, ‘‘gethot’’, and ‘‘melt’’ (Brook et al., 1984, 2003; Novick and Nussbaum,1981; Gilbert et al., 1982; Lee et al., 1993). For example, studentsbelieved that gas particles increase in size with the change fromsolid to liquid to gas (Haidar and Abraham, 1991).

Students believed that air flows from one place to anotherlike water but is unevenly distributed. According to somestudents, atmospheric pressure pushes the gas molecules down(Lin et al., 2000); air does not exert the same pressure indifferent directions (Brook et al., 2003); and gas particles areunevenly scattered in any enclosed space (Novick and Nussbaum,1981; Lee et al., 1993; Cho et al., 2000). Moreover, studentssupposed that when the air is compressed, particles are compactedlike a solid and do not move or they stick together (Lonning, 1993).Some of the students thought that when the air is compressed in asyringe, air moves toward the opening of the syringe (Lee et al.,1993). She (2002) examined the process of conceptual changerelated to air pressure and reported that most of the studentsbelieved that air cannot be compressed. They also thought that airpressure has a direction.

Moreover, some naive conceptions have been identifiedregarding cold and warm air. Most students thought that aballoon would blow up or get larger due to hot air or heatinstead of thermal expansion. Hence, they believed that hot airwould rise and cold air would go down in a bottle, so there washot air or heat in the top and cold air in the bottom. In addition tothese, some students believed that when a substance evaporates, itbecomes invisible and it no longer exists (Lee et al., 1993). Moreover,the stereotypical views like ‘air is everywhere’ and ‘hot air rises’ wereoften stated by pupils (Sere, 1986). Related to the kinetic theory ofgases, students had some major alternative conceptions; for exam-ple, they considered that atmospheric pressure pushes gas mole-cules down; gas molecules rise and stay away from heat; andmolecules expand when they are heated (Lin et al., 2000). Studentsbelieved that when the temperature is lowered, gas particles sink tothe bottom of a container and the majority of the high schoolstudents explained the decrease in volume of a gas on cooling not interms of decreasing particle motion but in terms of increasingattractive forces (Novick and Nussbaum, 1981). Sometimes students’intuitive thinking can be one of the sources of misconceptions; forexample as a cause of deflation of the balloon students said, ‘‘Theenergy gradually dies, so the gas motion stops and balloon deflates’’(Haidar and Abraham, 1991). Accordingly, most of the studentswere not able to draw the appropriate representation of gas particlesinside a flask (Lin et al., 2000). Nussbaum (1985) asked how thedistribution of gases would be after evacuating some of the air froma flask. While some of the students (14 years old) thought that theupper part of the flask is filled with air, the others believed that thelower part of the flask is filled with air.

Students also had difficulties in understanding and applyingthe ideal gas law appropriately. Students memorized the idealgas formula, PV = nRT without understanding it conceptually(Lin et al., 2000). Many of the students focused on the

relationship between two variables in the ideal gas law regard-less of the others. For instance, they assumed that ‘‘Pressure isalways inversely proportional to the volume’’ and ‘‘Pressure isalways directly proportional to the temperature’’ (Kautz et al.,2005a). From the microscopic viewpoint, some of the studentsbelieved that the density of a gas decreases as a result ofexpansion and so in order to keep the pressure constant, thespeed of the particles must increase. Some of them thoughtthat when a gas is enclosed in a smaller volume, gas particlesare more likely to come together and collide with each otherfrequently. Consequently, the temperature and then averagekinetic energy increases; that is, they ‘‘Mistakenly assume thatmolecular collisions generate kinetic energy’’ (Kautz et al., 2005b).Some students even thought that these collisions may result in achange of atomic size (Griffiths and Preston, 1992). Similarly, in thecontext of the diffusion concept, students thought that molecularmotion of gases stops at an ending point in the diffusion. Inaddition, students believed that the diffusion rate of gasesincreases with increasing molecular weight (Cho et al., 2000).

Consequently, research findings about students’ conceptionsof gases indicated that gases are one of the abstract subjects inwhich students have difficulties in understanding. As statedbefore, the constructivist approach considering the students’prior knowledge and stressing the active engagement of studentsin the learning process is influential in providing meaningfullearning (Mayer, 1999). Accordingly, case-based learningenvironments providing both real life examples and socialexperience promote constructivist learning (Jonassen, 1994).Case-based instruction aims to teach the topic through cases.Cases are composed of two main parts: one of them is the casesituation for the study and the other is the questions related tothe case. Cases are complex teaching instruments in the formof narratives. The narratives are generally based on real lifesituations. Teacher and students study the problems related todaily life cooperatively (Wassermann, 1994). Cases can varyfrom a paragraph or two to a dozen pages but it is suggestedthat long cases be distributed and read before the class toprevent students getting confused and becoming lost in details.Learners solve the presented problem using their backgroundknowledge (DeYoung, 2003).

At the end of each case, some study questions related to thecases help students to evaluate outcomes, concepts, and sub-jects of the case. The purpose of the study questions is tofacilitate student understanding, rather than simply asking forthe names, dates, or labels. Case-based teaching providesopportunities for students to study in small groups and discusstheir responses before the whole-class discussion sessionoccurs. During examination of the case, the teacher managesthe class discussion by promoting the critical analysis of thereal life problems with the students and helping students todiscover the meaning. The teacher avoids imposing his or herown thoughts. Rather s/he lets students interpret their ownunderstanding during the period of discussion (Wassermann,1994).

Though studies regarding case-based instruction in scienceeducation are limited, some research studies showed that

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case-based instruction was effective in improving students’critical thinking skills and increasing their interest in learningscience (Gabel, 1999); making laboratory courses interesting andrelevant to daily life (Frerichs, 2012); establishing a link betweenscience and non-science classes (Richmond and Neureither,1998); and increasing students’ performance and academicknowledge regarding the nervous system (Çakır, 2002) and thehuman reproductive system (Saral, 2008). Moreover, case-basedlearning was found to be an effective method for remediatingstudents’ misconceptions in the context of solubility equilibrium(Çam, 2009); solids, liquids and gases (Ayyıldız and Tarhan,2013); and gene biodiversity (Gallucci, 2007). Consequently, itcan be said that case-based instruction is a teaching strategy forpromoting students’ engagement in learning science and mak-ing improvements toward conceptual change. In the present study,the aim was to provide four conditions for conceptual change thatPosner et al. (1982) identified; dissatisfaction, intelligibility, plau-sibility, and fruitfulness.

Although the related literature suggests that case-basedinstruction would be more effective compared to the traditionalinstruction, the success of any teaching instruction depends onseveral issues. To illustrate, both students and teachers inTurkey are not accustomed to any active teaching methods,i.e. case-based instruction. Teachers in Turkey are used toteaching in a traditional way. However, in case-based instruction,the role of the teacher will change from the disseminator ofinformation to the facilitator that guides students to constructtheir own knowledge. Similarly, the role for the students willchange from listening passively to participating in discussions toreveal their ideas explicitly. As Airasian and Walsh (1997) suggest, itwould take some time for students and teachers to get accustomedto these roles. Woods (1994) observed that teaching habits canmake it difficult for teachers to accept change. Moreover, Gallucci(2007) claimed that instructors’ enthusiasm using the case-methodis an important factor contributing to the effectiveness of thismethod. In addition, more class time is needed for students toconstruct knowledge, and this presents a difficulty for teachers whoneed to complete a topic in an allocated period of time determinedby the curriculum. This also affects the application of case-basedinstruction. If a teaching method was not applied genuinely inthe classroom, even if it is effective theoretically, one cannotobtain positive results in practice. Similarly, success of ateaching approach may depend on the nature of the topicand the characteristics of students. Students with an externallocus of control, where success or failure is attributed toexternal issues such as luck, fate etc., rather than their personalcontrol, tend to do better when instructed in a teacher-centeredway (Peterson, 1979). Moreover, it is not clear if suggestedteaching methods based on constructivism would be successfulfor different subjects or contents (Airasian and Walsh, 1997).Cobern et al. (2010) also mentioned the nature of a topic doesinfluence the choice of the most effective method of instruction.Therefore, we thought that it would be meaningful to comparecase-based instruction with traditional instruction in order toreveal which one would be more effective for the students in ourcountry in the context of the gases topic.

MethodologyDesign of the study

Non-equivalent control group design was used in this study. Inthis design, although the groups being compared are randomlyassigned as control and experimental, the subjects are notrandomly assigned to these groups; instead already formedgroups are used (Gay and Airasian, 2000). Two schools participatedin the current study; one of them was a public high school, theother was an Anatolian high school. In Turkey, after elementaryeducation, students enter a nation-wide examination to be placedat different high school types. Based on the scores achieved fromthis exam, students make some preferences. Students gettinghigher scores were placed at Anatolian high school; however, thereare also score differences among Anatolian high schools. In thepresent study, students enrolled in the Anatolian high schoolscored more than the public high school students, but there wasnot a big score difference between these students. The sameNational Curriculum is followed in these schools and schoolswere similar in terms of the school facilities and the way teachersdeliver chemistry lessons. Moreover, these schools were in thesame district and the socio-economic backgrounds of studentswere similar. To control for the various variables that can influencestudents’ achievement, students’ pre-scores regarding attitude,motivational beliefs, understanding of gas conceptions andscience process skills were taken into account (Pintrich et al.,1993; Brotherton and Preece, 1995; Harlen, 1999; Koballa andGlynn, 2007). Therefore, prior to the treatment, a science processskills test (SPST), an attitude scale towards chemistry (ASTC), themotivation section of motivated strategies for learning question-naire (MSLQ) and the gas concept test (GCT) were administered toboth experimental and control group students before instructionto determine whether there was a significant mean differencebetween two groups in terms of students’ knowledge about gasconcepts, students’ attitude towards chemistry, science processskills and their motivation. After treatment, the gas concept test(GCT) was distributed to both groups of students in order to revealwhether there is significant mean difference in terms of students’conceptions of gas concepts.

Sample

All 10th grade students in Ankara, the capital city of Turkey,were determined as the target population. However, since it ishard to get in touch with the whole target population, all the10th grade students in Çankaya, which is the one of thedistricts in Ankara, were identified as an accessible population.After conversations with high school chemistry teachers inÇankaya, the schools in which the teachers volunteered to usea new teaching method in their chemistry lessons were chosenas implementation schools. Therefore, one public high schooland one Anatolian high school were selected from the identifiedaccessible population by the convenience sampling technique.In each school, one of the classes was randomly assigned as theexperimental group and the other class instructed by the samechemistry teacher was assigned as the control group. Therefore,two classes from each school were assigned randomly as the

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experimental and the control group. Random selection was doneby flipping a coin. In each school, classes were labeled as class Aand class B. Heads side of the coin was matched with theexperimental group while tails side of the coin determines thecontrol group. For example, for class A, we flipped a coin and if itwere heads, that class was assigned as the experimental group.Two instructional methods; case-based instruction on conceptualchange conditions (CBCC) and traditionally designed chemistryinstruction (TDCI) were assigned to the experimental and controlgroups respectively. Forty five tenth grade students (22 boys and23 girls) from the Anatolian high school and 83 tenth grade students(44 boys and 39 girls) from the public high school participated in thisstudy. There were 63 students instructed by CBCC in the experi-mental groups (31 girls and 32 boys) and there were 65 students(31 girls and 34 boys) instructed by TDCI in the control groups intotal. The age range of the participants was 15–16. In each school,students were instructed by the same chemistry teacher for 12 weeks.

Instruments

The science process skills test (SPST), the attitude scale towardschemistry (ASTC), the motivation section of the motivatedstrategies for learning questionnaire (MSLQ) and the gas con-cept test (GCT) were used as pre-test measuring instruments inorder to determine the pre-existing differences between controland experimental group students before instruction. Aftertreatment, in order to determine the effect of case-basedinstruction on overcoming alternative conceptions about gasconcepts, GCT was administered to both groups as a post-test.In addition to GCT, after instruction semi-structured interviewswere conducted with students from both groups in order toobtain deeper information regarding their conceptions aboutgas concepts. Finally, after treatment, a feedback form for case-based instruction was used as a research instrument in order toreveal experimental group students’ opinions about the effec-tiveness of case-based instruction.

Gas concept test (GCT)

The Gas concept test included 26 multiple choice questionswith five alternatives. Many of the questions in GCT were takenand adapted from the earlier studies related to the gas topic(Azizoglu, 2004; pek, 2007). These questions were based oncommon alternative conceptions about gas concepts in theliterature (Novick and Nussbaum, 1978, 1981; Brook et al.,1984; Sere 1986; Mas et al., 1987; Stavy, 1988, 1990; Rollnickand Rutherford, 1990; Benson et al., 1993; Lee et al., 1993;De Berg, 1995; Cho et al., 2000; Lin et al., 2000; Niaz, 2000;Sanger et al., 2000; She, 2002; Givry, 2003). At the beginning ofthe development stage of the test, the instructional objectivesfor gas concepts were stated based on the national curriculum.This test covered the following subtopics: (1) properties of gases,(2) volume of gases, (3) kinetic theory of gases, (4) diffusion ofgases, (5) pressure of gases, (6) gas laws (Charles law, BoyleMarriott, Dalton, Avogadro, Gay Lussac), (7) ideal gas laws, (8)partial pressure of gases.

Each item of the GCT was examined in detail by fourchemistry educators and six chemistry teachers in terms of

content validity and format. Based on these recommendations,the corrections on the test were made. Afterwards, GCT waspiloted with 332 high school students from different schoolswho had learned the gas concept previously. The Cronbach-alphavalue of the multiple-choice test was 0.70 in the reliability analysis.There was not any major change to the items on the test after thepilot study. Some questions involved diagrams related to represen-tations of submicroscopic particles in order to make the questionsmore comprehensible. The final form of the test was administeredto both group of students (control & experimental) as a pretest and aposttest in order to evaluate their understanding of concepts relatedto gases (see some examples of test items in Appendix I). Please notethat all questions in the GCT were written in Turkish and the presentarticle reports translated versions. The first author, who was a PhDcandidate in chemistry education at the time of the study, translatedquestions in the GCT into English independently. Then, the equiva-lence of the translated and original version was checked by thesecond author, who is an instructor in the chemistry educationdepartment. They discussed any disagreements together in order toreach a consensus for the final English version of the GCT.

The science process skills test (SPST)

The test, which included 36 multiple choice questions relatedto identifying variables, operationally defining variables, iden-tifying appropriate hypotheses, interpreting data and designingexperiments, was originally developed by Okey et al. (1982). Itwas adapted into a Turkish version by Geban et al. (1992) foundCronbach’s alpha to be 0.85 which indicated that the instru-ment is reliable enough. Some sample items are as follows(Table 1).

The motivated strategies for learning questionnaire (MSLQ)

MSLQ is a self-report questionnaire developed for a collegecourse by Pintrich et al. (1991) to evaluate students’ motivationalorientations and their use of different learning strategies. It usesa 7-point Likert scale from ‘‘not at all true of me’’ to ‘‘very true ofme’’ measuring students’ motivational and learning strategiesconstructs. Basically there are two main sections in MSLQ, amotivation section and a learning strategies section. In thecurrent study, only the motivation section of MSLQ was usedfor both experimental and control group students to determinestudents’ perceived motivation before treatment. In the motiva-tion part, students’ goals and belief values for a course, theirbeliefs about their skills to succeed, and their anxiety about testsin a course were evaluated by 31 items. MSLQ contains six sub-headings: (1) intrinsic goal orientation (IGO), (2) extrinsic goalorientation (EGO), (3) task value (TV), (4) control of learningbeliefs (CLB), (5) self-efficacy for learning and performance(SELP), (6) test anxiety (TA). Sungur (2004) adapted and trans-lated MSLQ into Turkish for a biology lesson. In the currentstudy, minor changes were made to the instrument developed bySungur (2004) and it was used for the chemistry lesson. Table 2shows sample items for each sub-section of the questionnaire.

This instrument was piloted with 324 tenth, eleventh and twelfthgrade science students. As seen from Table 3, the instrument wasfound reliable enough.


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Attitude scale towards chemistry (ASTC)

This scale included 15 items and was developed by Geban et al.(1994) to determine students’ attitude toward chemistry as aschool subject. It is a 5-point Likert scale as follows: ‘‘stronglyagree, agree, undecided, disagree, and strongly disagree’’.Cronbach’s alpha was found to be 0.88 indicating that ASTChas good reliability. Some sample items from ASTC are: ‘‘I likereading books related to chemistry’’, ‘‘Chemistry is not importantin our daily life’’ and ‘‘I get bored when I study chemistry.’’

Interview questions

After treatment, semi-structured interviews were conducted with atotal of sixteen students from both experimental and control groups.Eight students from the control group (3 girls, 5 boys) and eightstudents from the experimental group (4 girls, 4 boys) were inter-viewed. The criterion for selecting interviewees from each group ofstudents was based on post-GCT scores. Two high, four mediumand two low scorers from each group attended the interview.

Interviewees were selected using the technique that Thompsonand Soyibo (2002) used in their study in order to categorizestudents’ attitudes into categories using the mean of the posttestscores and standard deviations. Similarly, in the present study,students whose scores were above one standard deviation from themean were regarded as high achievers. Students whose scores were

within one standard deviation below the mean and one standarddeviation above the mean were considered as being moderate orneutral achievers. Students with scores below one standard devia-tion from the mean were classified as low or poor achievers. Fromthe pool of high, moderate and low achiever students, two highachievers, two low achievers and four moderate achievers for bothexperimental and control groups were randomly selected by usingthe option (select random sample of cases) in SPSS. Extra questionswere not prepared; instead test items used in GCT were usedduring the interviews. The purpose of the interviews was to probethe questions asked in the concept test and detect the reasons forselecting the wrong alternative. Also, both control and experimentalgroup students were compared after treatment in terms of theirconceptions about the gas topic in the light of the interviews. Theelapsed time between the gas concept test and the interviews wasabout one to two weeks. The first author of the present study whowas not a teacher of the students interviewed the students. Eachinterview was conducted individually and lasted about 50 minutes.All interviews were audio-taped and transcribed later.

Treatment (CBCC vs. TDCI)

Before the implementation of the current study, necessary legalpermissions were received and all the materials used duringthe instructions were examined by the ethics committee ofthe university. During the implementation of the study, studentswere not harmed in any way (physically or mentally). All thestudents consented to participate in the study. Besides, the issueof confidentiality was emphasized in a way that names of thestudents would not be reported anywhere and the accessibledata would be seen just by the researcher. Students were toldthat they would not be graded according to their responses and

Table 1 Sample items of the science process skills test

Sample items in SPST

A police chief is concerned about reducing the speed of autos. He thinks several factors may affect the automobile speed. Which of the following isa hypothesis he could test about how fast people drive?(A) The younger the drivers, the faster they are likely to drive.(B) The larger the autos involved in an accident, the less likely people are to get hurt.(C) The more policemen on patrol, the fewer the number of auto accidents.(D) The older the autos the more accidents they are likely to be in.

A science class is studying the effect of wheel width on ease of rolling. The class puts wide wheels onto a small cart and lets it roll down an inclinedramp and then across the floor. The investigation is repeated using the same cart but this time fitted with narrow wheels.How could the class measure ease of rolling?(A) Measure the total distance the cart travels.(B) Measure the angle of the inclined ramp.(C) Measure the width of each of the two sets of wheels.(D) Measure the weight of each of the carts.

Table 2 Sample items of the questionnaire

Sub-headings Sample items

Intrinsic goal orientation In a class like this, I prefer course material that arouses my curiosity, even if it is difficult to learn.Extrinsic goal orientation If I can, I want to get better grades in this class than most of the other students.Task value I think the course material in this class is useful for me to learn.Control of learning beliefs If I try hard enough, then I will understand the course material.Self-efficacy for learning and performance I’m confident I can learn the basic concepts taught in this course.Test anxiety When I take tests I think of the consequences of failing.

Table 3 Reliability coefficients of MSLQ

N (sample size) IGO EGO TV CLB SELP TA

ENG 356 0.74 0.62 0.90 0.68 0.93 0.80TUR (Sungur’s) 488 0.73 0.54 0.87 0.62 0.89 0.62TUR (current) 324 0.69 0.75 0.64 0.69 0.70 0.77


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that it was important to respond to the presented tests assincerely as possible.

One hundred and twenty-eight tenth grade students froma public high school (N = 83) and an Anatolian high school(N = 45) were the participants in the present study. In eachschool, one of the classes was randomly selected as experi-mental and one class as the control group. The experimentalgroup students were instructed by case-based instruction basedon conceptual change conditions (CBCC) whereas the controlgroup students were instructed by traditionally designedscience instruction. All groups of students in the two schoolsfollowed the same National Curriculum and the same conceptsfor the same amount of time. For example, similar daily lifeexamples and alternative conceptions were mentioned in bothgroups, and no laboratory work or demonstrations was con-ducted in both groups. However, in the control group, theteacher transmitted information while in the experimentalgroup the students tried to construct this knowledge. In eachschool, the same teacher instructed both control and experi-mental group students. The teacher was male in one schoolwhile the other teacher was female.

A month before treatment, a teacher manual containingtheoretical information about case-based instruction and theconceptual change model, cases that students will carry out ingroups, and some directing questions for the teacher to guidestudents’ discussion were given to the teachers. After a week,for three weeks, approximately one-hour meetings were con-ducted with the teachers. In these meetings, case-based instruc-tion, the conceptual change model, the roles of the teacher andthe students in case-based instruction were again explained tothe teachers. Teachers were trained about the new method andhow to implement case-based instruction based on conceptualchange conditions for the gas unit in chemistry. For thispurpose, the researcher explained a sample lesson using theatmospheric pressure case. Moreover, how the teachers wouldprovide four conditions of conceptual change was discussed inteacher training sessions. To clarify, it was mentioned thatdiscussion of study questions in the case was designed to createdissatisfaction among students. Therefore, the teacher shouldtake students’ opinions about these questions and discuss thereasons for different answers with the class. At that stage, theteacher may ask some more questions to promote students’dissatisfaction with the ideas. For the intelligibility and plausibilitysteps, the teacher was to ask some prompting and challengingquestions and guide students to find the intelligible and plausibleconclusion. For the fruitfulness step, the teacher was to encouragestudents to link the concept with daily life. Actually, classroomobservations showed that teacher training sessions were successfulbecause teachers took these suggestions into account and couldapply the conceptual change conditions successfully in theclassroom.

Experimental group students received case-based instructionbased on conceptual change conditions. Prior to treatment, ineach school experimental group students were divided intogroups of four or five students by their chemistry teachers soas to be as heterogeneous as possible in terms of their chemistry

achievement and general attitude toward chemistry. Then, theteachers gave information about the new teaching method; whatthe case-based instruction is and how it is applied in classroomsettings emphasizing the roles of students in detail. The role ofstudents in each group was to read and discuss the givenproblem and scenario under teacher guidance. The role ofteachers was to provide an arrangement of groups and avoidgiving the direct answers of the case-based learning questionsduring group discussions. The same content was covered inexperimental group classes as in control group classes butexperimental group students were instructed basically by meansof the presented cases, problems or scenarios working in smallgroups. Students’ alternative conceptions of gas concepts andremedies based on conceptual change conditions were takeninto account while preparing the cases. In this study, a total offifteen cases generally based on real-life events and experimentswere used for gas concepts (see a case example in Appendix II).The cases were about atmospheric pressure, Avogadro’s law,Boyle’s law, Charles’s law, Gay-Lussac’s law, Dalton’s law, acombination of Boyle–Avogadro–Charles’s laws, diffusion rate(two cases), partial pressure, properties of hot and cold air, andproperties of gases (four cases) (for more information on cases,please see Appendix III). For the preparation of cases, research-ers investigated daily life applications and some experimentsrelated to gas concepts from the chemistry books and internetresources. Then, case scenarios were developed from thesesources. Three cases were taken from the studies of Ipek(2007) and Bilgin et al. (2009). Similarly, study questions relatedto them were prepared based on students’ alternative concep-tions about gas concepts found in the literature. To illustrate,some examples of the study questions related to the case given inAppendix II were: ‘‘Compare the inside pressure of a deflatedbicycle tire with the outside pressure’’; ‘‘What can be said aboutthe motion/state of gas particles in the deflated bicycle tire?’’;‘‘Can using up the energy of the gas particles in time and ceasingtheir motion be the reasons for deflation of the bicycle tire?Why?’’; ‘‘Draw the distribution of the gas particles in the inflatedand the deflated bicycle tire.’’ These study questions wereformed in the light of the alternative conceptions: ‘‘the pressureinside a deflated bike tire or balloon is different from thepressure outside’’: ‘‘the energy gradually dies, so the gas motionstops and balloon deflates’’: and ‘‘gas particles are unevenlyscattered in any enclosed space.’’

After the preparation, for the content validity, these casematerials were given to two teachers who were involved in theimplementation of them and two chemistry educators. After thefeedback, cases were reorganized if required. Before treatment,the cases were discussed with the chemistry teachers to decidewhere the cases will fit in the class schedule.

In experimental groups, students in small groups analyzedthe given cases and answered the related questions. Afterward,group members shared their ideas with the whole class andclass discussion began. Discussion continued until a reasonableor plausible answer(s) were found to the case questions. Mean-while, experimental group teachers guided students by askingopen-ended and challenging questions and prompting further


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thinking. Since the discussion of cases began and ended in class,students did not have opportunities to search or investigate thesubjects from different resources such as books, internet, andlibrary. Therefore, sometimes the needed information or clueswas provided in the class materials required to solve the givenproblem. For example, during the implementation of the air bagcase, the reaction equation (2NaN3(s) + heat - 2Na(s) + 3N2(g))was given by the teacher after students’ discussion about swelling ofthe air bag. And then one of the group members wrote the answers.This active learning environment allowed students to work ingroups, identify learning issues, share related information with theirclassmates and develop critical thinking ability about events.

Since one of the purposes of the present study was to remedystudents’ alternative conceptions about gas concepts by case-basedinstruction based on conceptual change conditions, scenarios orproblems were prepared by considering these alternative concep-tions. The teaching strategy was planned by considering theconceptual change principles needed to assist students in removingtheir alternative conceptions, the conceptual change principlesbeing dissatisfaction, intelligibility, plausibility, fruitfulness.

For example, experimental group students were presentedwith the atmospheric pressure case and asked why water boilsfaster above sea level. The dissatisfaction created in students’minds by this case and learning environment provided studentsopportunities to discuss the given scenario or event with boththeir group mates and classmates. While studying the case aboutatmospheric pressure, each group began to discuss the reasonsfor boiling water faster on the mountain. At first, some groupscould not relate that event to the atmospheric pressure; they justsaid that the boiling point should be lower. At that point, theteacher tried to prompt students’ further thinking, making themthink about the relationship between the reason for boilingwater faster on the mountain and atmospheric pressure usingan open-ended, challenging question: Teacher: Think about theatmospheric pressure. How does it change with the altitude?

After this clue, students stated their reasoning

Some students: Water boils faster at the mountain since atmo-spheric pressure increases with increase in altitude.

Most of the students: Water would boil faster due to thedecrease in atmospheric pressure with altitude.

After group discussions, each group revealed its ideas and triedto convince the other groups with different viewpoints to accept itsviewpoints. Most of the group had the correct reasoning

Most students: In the mountains, there is less atmosphericpressure, in order to boil faster, water should boil at a lower boilingpoint, less atmospheric pressure causes the water boil faster.

Some students: As you go towards the mountains, pressureincreases. Since pressure increases, water molecules collidemore and water boils at a lower temperature, that is why waterboils faster at the mountain

A group told: You are confusing vapour pressure with atmo-spheric pressure. You say that pressure increases on the mountains,this is atmospheric pressure not vapor pressure. Atmosphericpressure is the pressure exerted by air

Teacher: What is boiling?

A student: Boiling occurs at the temperature where atmo-spheric pressure is equal to the vapor pressure

Teacher: What do you say; in order to boil faster, watershould boil at a lower temperature or higher temperature than100 1C, right?

Students: Lower temperatureTeacher: If you say that boiling occurs when atmospheric

pressure is equal to vapor pressure. Should we decrease orincrease atmospheric pressure in order to make water boil at alower temperature

Students: DecreaseTeacher: So what do you think? What should atmospheric

pressure be for the water to boil faster at the mountain?Students: If the water boils faster, the pressure on it should

be lower hence the atmospheric pressure should decrease whenyou go higher

The whole class discussion continued until the intelligible andplausible answer(s) were found by the students. As understood fromthe dialogues, the teacher had an important role in guiding thediscussion and helping students to construct the knowledge cor-rectly. Sometimes students gave extraneous or irrelevant responses.In this case teachers asked challenging questions to extend thethinking about the topic without changing the direction of thediscussion. In order to make the information more meaningfuland permanent, other questions related to the topic were asked. Forexample, the teacher asked another question ‘‘why do the climbersmake a camp at certain altitudes while climbing the mountain or why dotheir nose bleed while climbing?’’. Besides, he asked them whetherthey have had such an experience or not. None of the students hadsuch an experience but one of them said that he saw it in a movieand explained the cause of this event as pressure change. After that,students were asked ‘‘Why people living in uplands or plateau areruddy-cheeked?’’ The responses were interesting. While some groupsof students thought that it was the consequences of the healthy diet,most of them specified it was due to the atmospheric pressure. Theteacher also initiated several discussions about the oxygen amountin uplands as well as adaptations and transport of oxygen in humanblood. Through this case, students not only learned how theatmospheric pressure changes with altitude, they gave anexplanation to some real life events. In this way, the fruitfulness(or usefulness) stage of the conceptual change was provided. Atthe end of the instruction, GCT was administered to bothgroups of students as a posttest to measure the change inalternative conceptions about gases.

Students in the control group were instructed by traditionalinstruction in which a teacher-centered learning strategy wasadopted. In traditionally designed classes, teachers defined andexplained the concepts and solved related or similar questionsfor students. For example, during teaching the atmosphericpressure concept, a control group teacher mentioned thatatmospheric pressure decreases with altitude. At that point,he asked whether water boils at the mountain at a lower orhigher temperature or the same temperature. Different answerscame from students. The teacher told the students that waterboils at a lower temperature than 100 degrees Celsius on themountains. Further questions used in experimental group


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classes were also asked but a discussion platform was notcreated in these classes. In some cases, students failed torespond to the questions. In this case, the teacher, himself, gavethe answer to the question. For instance, he clearly defined thatthe people living in the uplands look pink since the number ofred blood cells in their blood increases after a while. In controlgroups, students were only motivated by teacher-directed ques-tions, and there were not any activities like group work includedduring the teaching of a gas topic. Students in traditional classesasked very few questions. They generally responded to thequestions asked by the teacher. Teachers allowed a certainamount of time to solve the presented question. Meanwhile he orshe sat on his or her table or walked around the class. Thenstudents’ opinions about questions were usually taken verbally andtheir questions were solved on the board by the teachers. Whenstudents asked any questions about the subject matter, the teacheranswered them. However, students simply acted as passive listenerstaking notes. Instruction in the control group was based oninforming students about gas concepts. Similar daily life examplesand alternative conceptions to those presented to the experimentalgroups were also mentioned in the control groups by the teachers.

After completing the case activities, the researcher and a PhDstudent in chemistry education observed the instruction in theexperimental classes once a week and completed the treatmentverification checklist which was prepared by the researcher in orderto check whether the case-based instruction method was applied asrequired. The treatment verification checklist consisted of two parts:the first part included ‘‘yes’’ or ‘‘no’’ type items and the second partincluded items with a 5-point Likert-type scale (always, usually,sometimes, rarely, and never). The percentages of items marked as‘‘usually’’ and ‘‘yes’’ were 75%. This checklist indicated that case-based instruction was implemented in accordance with the purposeof the study. Thus, treatment fidelity was provided with the help of atreatment verification checklist.

Limitations of the study

As limitations, the students were not randomly assigned to thegroups. This may affect the representativeness of the sample.Another limitation may be that the GCT was not distributed tostudents as a delayed test so we could not assess the effect ofcase-based instruction on knowledge retention. Moreover, it shouldbe noted that the novelty effect, which means the increased interest,motivation, or engagement of participants because of doing some-thing different, not because it is effective or better may threaten theexternal validity of the study. In addition, the expectancy effect,where researchers expect the effectiveness of case-based instructionto be greater than traditional instruction, may have an influence onthe effect level of case-based instruction (Taber, 2008).

ResultsStatistical analysis of pre-scores

All statistical analysis was carried out at the 0.05 significancelevel by using the statistical package for the Social Sciences(SPSS) 18. Before treatment, pre-ASTC, pre-SPST, pre-GCT and

pre-MSLQ scores of students in both control and experimentalgroup were compared to check the equality. After meeting theassumptions of normality, independence of observations andequal variances, independent samples t-test was used in orderto check the equality of both experimental and control groupstudents’ pre-ASTC, SPST and GCT scores. Before treatment, itwas found that experimental and control group students werenot significantly different from each other with respect to theirpre-attitude towards chemistry (ASTC) scores t(126) = 0.95,p = 0.34, their science process skills (SPST) scores t(126) = �0.45,p = 0.65, and pre-existing knowledge about gas concepts (pre-GCT)scores t(126) = �0.24, p = 0.16. Table 4 gives information aboutmean values of pre-ASTC, pre-SPST, pre-GCT and post-GCT scoresfor both control and experimental group students.

Moreover, after meeting normality, homogeneity of covar-iance matrices and independence of observations assumptions,one-way MANOVA was conducted before treatment to checkwhether control and experimental students were different withrespect to motivational variables. It was found that there was nostatistically significant mean difference between experimentaland control group students with respect to the students’motivational collective dependent variables of intrinsic goalorientation (IGO), extrinsic goal orientation (EGO), task value(TV), control of learning beliefs (CLB), self-efficacy for learningand performance (SELP), test anxiety (TA), Wilks l = 0.92,F(6,121) = 1.68, p = 0.13. Table 5 describes mean values of students’pre-motivational scores across both groups of students.

Statistical analysis of post-GCT scores

After meeting normality, homogeneity of variance and independence ofobservations assumptions, one-way ANOVA was performed toanswer the first research question. A significant mean difference(F(1,126) = 49.91, p = 0.000) between experimental and controlgroup students with respect to the treatment effect on students’understanding of gas concepts was found. The Eta-Squaredvalue of 0.28 indicated the difference between experimentaland control groups was not small. In other words, 28% of thevariance of the dependent variable was associated with thetreatment. Also, the power value of 1.000 showed the differencebetween experimental and control groups aroused from thetreatment effect. As seen from Table 4, mean scores of post-GCTscores were 11.74 and 16.84 for control and experimental groupstudents respectively. In sum, case-based instruction based onconceptual change conditions was an effective method forpromoting students’ understanding about gas concepts.

Results of gas concept test (GCT) and interview

Eight experimental and eight control group students were theinterviewees. Frequency analysis of students’ responses for

Table 4 Mean values of pre-ASTC and pre-SPST, pre-GCT and post-GCT scores

Group

Pre-ASTC Pre-SPST Pre-GCT Post-GCT

Mean Mean Mean Mean

CG 54.50 17.18 10.21 11.74EG 52.88 17.60 10.33 16.84


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each item in GCT and interview results indicated that experi-mental group students had better understanding of gas conceptsthan their control group counterparts and they performed betterreasoning in their answers than that given by control groupstudents. However, some alternative conceptions were still pre-sent for both groups of students. Table 6 shows some alternativeconceptions detected by GCT.

Substance between the particles of a gas

When students were asked what is present between the particlesof a gas, item analysis of GCT showed that 74.2% of theexperimental group students believed that there was nothingbetween gas particles, however only 16.9% of the control groupstudents answered this question correctly. Interview findingsalso confirmed the difference between experimental and controlgroup students’ understanding. For example, six out of eightexperimental group students knew that there is nothing betweenthe particles of a gas. On the other hand, six of the control groupstudents and two of the experimental group students believedthat since air is present everywhere, it might be also presentbetween the particles of a gas: ‘‘Air must be found among theparticles of a gas since it is available in everywhere.’’

Conservation of mass

For the conservation of mass, GCT results showed that 48.4% ofthe control and 82.3% of the experimental group students wereaware that mass was conserved. Interviews with students indicatedthat most of the experimental group students (six students) hadbetter understanding than control group students since they knewthat the total mass was conserved as a result of the burning ofpaper in a closed container. They expressed their reasoning bymeans of the law of conservation of mass in chemical reactions.However, two of the control group students and two of the

experimental group students believed that the total mass of thecontainer was the smallest in condition III where ash was formedafter burning paper because they only paid attention to the pictureignoring the chemical reaction inside the container: ‘‘If the mass ofthe paper reduces while burning, the mass of the container alsodecreases. So, condition III has less weight.’’

According to three control group students, condition III hasthe biggest mass due to the increase in pressure in thecontainer: ‘‘In condition III, the container is the heaviest due tothe fact that it contains gas. Paper is not a heavy substance, andwhen it is in gas state it accumulates, so it is likely to make an effecton the pressure. The pressure would affect the mass of thecontainer, but we cannot measure the pressure within the containerand I think the mass of the container increased.’’

Partial pressure

From the interviews, it was noticed that control group studentswere confused about the concept of partial pressure. They couldnot select the correct figure that represents the partial pressureof oxygen when a mixture of helium and oxygen gases was placedin a closed container. Instead, four of them tried to rememberthe related formula or have no idea about the concept of partialpressure. In addition to these, three of the students from thecontrol group expected to see the chemical reaction as an answerto the partial pressure of oxygen. GCT results also confirmed thesuperiority of experimental group students’ understanding withrespect to the partial pressure concept. Majority of the experi-mental (71.0%) and some control group (32.8%) students gavethe correct response by selecting the correct figure.

Distribution of air particles at 0 8C and 60 8C

For the distribution of air molecules at 0 1C and 60 1C, bothinterview and GCT results showed that experimental studentshad better understanding compared to control group students.For example, analysis of GCT revealed that 66.1% of experimentalgroup students and 10.8% of control group students selected thescientifically correct answer, which represents homogeneous dis-tribution of air with decreasing temperature when the temperatureis lowered to 0 1C. Similarly, when the temperature is increased to60 1C, a large difference between experimental (71.0%) and control(28.1%) group students giving the correct answer was detected.However, both groups of students had some alternative concep-tions (see Table 6). Interviews with students showed that, as for the

Table 5 Mean values of pre-IGO, pre-EGO, pre-TV, pre-CLB, pre-SELPand pre-TA scores

Dependent variables

CG EG

Mean Mean

Intrinsic goal orientation 19.31 20.68Extrinsic goal orientation 22.11 21.73Task value 30.38 30.82Control of learning beliefs 22.06 21.63Self-efficacy for learning and performance 40.20 40.01Test anxiety 20.95 19.63

Table 6 Percentage of alternative conceptions among experimental and control group students

Alternative conceptionsExperimentalgroup

Controlgroup

When the gas in the container is cooled, each of the gas particles shrinks or gets smaller 25.8 27When the gas is cooled, gas particles accumulated at the bottom of the container like liquids 8.1 42.9When the gas is heated in a constant-volume container, gas particles condense in the wall of the container 3.2 25With decreasing temperature, air molecules are getting closer to each other and accumulated in themiddle of the container

16.1 52.3

Air molecules are accumulated at the bottom of the container with decreasing temperature 9.7 36.9Heated air is accumulated on the walls of the balloon 9.5 14.1Air is located between the particles of a gas 12.9 55.4Hot air is lighter than cold air 30.6 28.1Hot air is heavier than cold air 1.6 12.5


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cooling of gas, four of the control group students believed that gasparticles are collected in the middle of the container due to somereasons like temperature is not too cold for sinking, gravitationalforce has no effect on them, or they stick to each other when cooleddown. Two experimental and four control group students thoughtthat gas particles sink to the bottom of the container when thetemperature was lowered to 0 1C though they were told that the gaswas still a gas at that temperature. Moreover, one of the interestinganswers came from experimental group lower achiever student. Hestated that; ‘‘When the gas is cooled down, the gas particles movetowards the upper part of the container since the upper part remainswarm, the particles move towards upward’’.When the temperature isincreased to 60 1C, two experimental and five control groupstudents thought that gas particles may condense on the walls ofthe container. They mainly think that when the temperature isincreased, gas particles move away from each other, they arepushed towards the sides of the container and so the pressureincreases. Increase in the pressure in the container leads studentsto have the idea that gas molecules may condense on the walls ofthe container. One of the control group medium achieversexpressed the accumulation of particles on the walls like this:‘‘The gas particles condense on the walls of the container when thegases are heated because the middle part of the container will be firstlyaffected from the heat since the heat is given from below’’.

Properties of cold and hot air

For the properties of cold and hot air, though experimentalgroup students had better understanding of the properties ofcold and hot air than control group students, both control andexperimental group students had some alternative conceptions.For example, ‘‘Hot air is lighter than cold air’’ was found to be acommon alternative conception and it was resistant to change.Apart from three students from the experimental group, noneof the students thought that hot and cold air have the samemass but different volume. Students generally believed thatparticles of hot air must be lighter than the cold air gasparticles: ‘‘Warm air rises and cold air sinks in a bottle, thereforewarm air is lighter since it rises’’. On the other hand, threestudents (two experimental group students and one controlgroup student) thought that hot air is heavier than cold airdue to daily life experiences. To clarify, two experimental groupstudents thought that since the electric wires are loose insummer and stretch in winter, hot air is heavier than cold air.Additionally, one of the control group students stated, ‘‘Hot air isheavier than cold air. I think from the example that foots of themountain are hotter, we feel the cold air more as we get upper and atthe top it is seen that snow does not melt easily in any way thereforeat the lower part of the mountain, there is hot air, at uppers there iscold air. Hot air is at lowers because hot air is heavier than coldair’’. This finding is also confirmed by the GCT results. In GCT,54.8% of experimental group students and 6.3% control groupstudents selected the correct alternative stating that hot and coldair may have different volumes but they have equal masses.However, both groups of students still had some alternativeconceptions regarding hot and cold air (see Table 6).

Gas pressure in a non-constant volume container

For gas pressure in a non-constant volume container, studentswere asked to predict the shape of the balloon when thecylinder is pushed downward without touch of elastic balloonto the surface of the vessel (as shown in the Fig. 1).

The answers given to GCT indicated that most of theexperimental group students (51.6%) made correct interpretationabout the shape of the balloon when the pressure inside the cylinderis increased compared to the control group students (34.9%).Similarly, interviews revealed that experimental group students’conceptions were more adequate. Experimental group studentshad better reasoning when they stated that a gas exerts pressurein each direction. On the other hand, about half of the control groupstudents (four students) and a few of the experimental groupstudents (two students) deduced that the balloon shrinks only fromthe bottom or only from above because they thought that pressureshrinks the balloon in the direction in which they exert the force tothe cylinder or the exact opposite direction to the force applied: Sincewe push the piston downward, only the bottom of the balloon mayshrink, there will be no change on the sides.

Gas pressure in a closed constant-volume container

For the gas pressure in a closed constant-volume container,students were asked to explain the reason for increase in thegas pressure in a closed constant-volume container withincrease in temperature. Item analysis of GCT revealed thatmost of the experimental (84.1%) and control group students(60.9%) selected the scientifically correct response as statingthat when the gas is heated in a constant-volume container, thenumber of collisions increase and so does the pressure. However,interview findings indicated that both control and experimentalgroup students had some alternative conceptions related to thereasons for increasing pressure with increasing temperature in aconstant volume container. For example, two of the experimentalgroup students believed that the size of the gas particles increasesdue to heating and so does the pressure and three of the controlgroup students thought that the size of the gas particles decreaseswith increase in temperature. Moreover, three of the control groupstudents supposed that gas particles might become heavier due totaking heat. However, as with the other concepts, experimentalgroup students’ understanding was better.

Change in speed of particles with the change in the volume ofcontainer

Interviews with students also revealed that when students wereasked whether the speed of gas particles changes with changingthe volume of the container, nearly all students gave incorrect

Fig. 1 Balloon in a non-constant volume container.


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responses. Only one of the high achievers from the experi-mental group and one of the high achievers from the controlgroup associated the speed of the particles with the tempera-ture. However, while five experimental and three control groupstudents believed that speed of the gas particles increases dueto the compression or increase in the number of collisions, twoof the experimental and three control group students thoughtthat speed of the particles of X(g) decreases with decrease involume. An alternative conception revealed by experimentaland control group students was that if the volume decreases,the speed of the particles increases due to the increase in thenumber of collisions. Students made a connection between thevolume and the change of the speed of the gas particles becauseof the change in pressure in a container.

Charles law

In the application of Charles’s law where students were asked toselect the environment that would decrease the volume of aninflated balloon tied by a rope, GCT results indicated that relativelymore control group students answered this question more correctly;76.9% of experimental and 79% of control group students gave thecorrect response. However, interviews showed that experimentalgroup students’ understanding was superior compared to that ofthe control group students. Interviews revealed that, though somestudents gave the correct answer based on their daily life observa-tions, they could not give any further scientific explanations. Forinstance, one of the control group students stated: ‘‘The samepressure and colder because I have done it at home and I saw theballoon shrinking. In fact, I do not know the reason’’. Interview resultsalso indicated that some students provided the correct answer to thisquestion but sometimes with wrong reasoning. Some of the controlgroup students thought that in order to decrease the volume of theballoon, external pressure must be increased. They believe that sinceexternal pressure increases in a cold environment, the balloonshrinks. One of the control group students thought that in the cold,gas molecules accumulate in the middle and so the volume of theballoon decreases. Some of the experimental group students (threestudents) and one control group student gave the correct answerwith correct reasoning. They associated the reason for the decreasein the volume of the balloon with the decrease of the speed, orkinetic energy of the particles or the distance between them.

Gay Lussac law

For the Gay Lussac law, the following question was asked: thereis a drop of mercury in the glass container as shown in Fig. 2.The mercury drop moves to the right or left depending on thepressure and temperature changing inside the glass container.

The apparatus of the room temperature (25 1C) is put intoenvironment 5 1C, students were asked to predict the directionof the movement of the drop of mercury.

Item analysis of GCT showed that most of the control (62.3%)and some experimental group (42.6%) students gave the correctanswer by stating the direction of movement as a result of decreasingpressure within the container with decreasing temperature. Theinterviews related to the effect of temperature on gas pressure in aconstant volume container showed that though most of the experi-mental (six students) and control group students (six students)predicted the direction of movement of the mercury droplet cor-rectly, some control group (three students) and some of the experi-mental group students (two students) had the wrong reasoning. Thefollowing excerpts indicate one of the control and experimentalgroup students’ ideas related to the direction of the mercury dropletas shown in the above figure regarding the cooling of the system:

When the temperature is lowered, the pressure inside thecontainer decreases. Gas particles might be getting smaller orclustered. Since the pressure decreases, the mercury moves to left.

I think it moves to the left because when the temperaturedecreases, mercury droplet will move towards the particles due toshrinkage. Mercury comes close to gas.

Students believed that gas pressure decreases in the containerdue to the shrinking or getting smaller of the gas particles orclustering of them in the container. As well, one student from eachgroup claimed that the volume changes due to a change in thepressure ignoring the constant volume container in the given systemand misusing the ideal gas law. The results concerning the applica-tion of Gay Lussac law indicated that some students were unable toestablish the relationship between temperature and the pressure of agas when all the other variables that affect the pressure of a gas arekept constant.

To conclude, both GCT and interview results indicated thatexperimental group students had superior understanding ofgas concepts compared to control group students. However,some of the alternative conceptions were still existent amongstudents from both groups even after instruction.

Discussion and implications

In the present study of gas properties, case-based instruction basedon conceptual change conditions promoted students’ understandingof gas concepts and was effective in remedying the alternativeconceptions of many of the students. This finding was supportedby other researchers (Çakır, 2002; Mayo, 2002, 2004; Rybarczyk et al.,2007; Saral, 2008; Çam, 2009). In the current study, real-life eventsand illustrations were used in the construction of the cases and thelist of study questions included alternative conceptions to createcontradiction in students’ minds related to the subject matter.Concepts associated with real life may have facilitated students’understanding and visualization of concepts. Furthermore in-groupand whole-class discussions helped to reveal alternative conceptionsbecause during those discussions, the existence of different ideas orpoints of view stimulated students’ thinking and awareness andhence played an important role in remedying alternativeFig. 2 Drop of mercury in the glass container.


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conceptions. This is parallel with Gallucci’s (2006, 2007) suggestionsthat small group discussions can be used to construct students’ ownconceptions. These features of case-based instruction seem to haveprovided better understanding of gas concepts compared to tradi-tional instruction.

In addition, a frequency analysis of students’ responses foreach item in GCT and interviews with students indicated thatcase-based instruction based on conceptual change conditionshelped to overcome students’ alternative conceptions andremedied most of them compared to the traditionally designedinstruction. However, though most of the experimental groupstudents had better understanding on the gas concepts, it wasimpossible to remedy all the alternative conceptions. Thismeans that students are persistent in their use of alternativeconceptions even after instruction designed to address thesealternative conceptions (Champagne et al., 1985; Anderson andSmith, 1987; Wandersee et al., 1994). However, still, case-basedinstruction was found to promote students’ conceptual under-standing of gas concepts.

This study has implications for chemistry teachers, teachereducation programs and textbook writers. Firstly, teachersshould be aware of possible alternative conceptions studentsmay have and consider students’ existing knowledge whendesigning lessons since new knowledge is constructed uponthe existing one. Since this study reported the effectiveness ofcase-based instruction on improving students’ understanding,we can recommend that teachers use case-based instruction tosupport meaningful learning. So, teachers should be trainedabout how to write and implement the cases in their routineclasses. They should also be encouraged to use new teachingtechniques like case-based instruction in order to enrich theirlessons. Secondly, teacher training programs in universitiesshould include this method of learning and presentexamples of the implementation of cases so that graduatepre-service teachers can know how to implement case-basedinstruction in their future classes. Lastly, textbook writersshould include effective cases in textbooks since instructionwith cases was found to be effective in enhancing students’understanding.

We can also make some recommendations for future study.In the present study, cases were not supported by use oflaboratory work or demonstrations. As a future study, effectivenessof the use of laboratory work or demonstration with cases could beevaluated with respect to written cases. Besides, as a future study,we can suggest that the effectiveness of case-based instruction onstudents’ retention of knowledge should be assessed.

Appendix I

Q1. The distribution of hydrogen gas molecules in a closedcontainer at 25 1C and 1 atm pressure was given in the next.(the circles (J) represent the distribution of hydrogen mole-cules), Which of the following diagrams illustrate the distribu-tion of H2 molecules when the temperature of the container islowered to �15 8C? (note: before responding to this problemstudents were told that at �15 1C hydrogen is still gas).

Q2. When a constant-volume closed container filled with agas is heated, increase in pressure is observed. In which offollowing alternative explains the reason of this event mostaccurately?

(A) Increase the size of gas particles(B) Increase in the numbers of particles when the gas

is heated(C) Becoming heavier of the gas when it is heated(*D) Increase in the number of the collisions when the gas

is heated(E) When the gas is heated, gas particles condense in the

wall of the container

Q3. A constant-volume container filled with air is connectedto a balloon as shown in the figure. When the tap of thecontainer is opened and the container is heated, it is observedthat balloon is swelling. Which of the following illustrate thedistribution of air the best after swelling the balloon? (dots (.)represent the molecules within air.)


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Q4. What exists between the particles of a gas?(A) Air(B) Water vapor(C) Other gases(*D) Nothing(E) Foreign substances (dust, dirt, etc.)Q5. As shown in following figure, a piece of paper is put in a

closed glass container in condition I. In condition II paper isburning and in condition III ash is formed. In all three cases,glass container is weighted. Accordingly, which one of thefollowing is true?

(A) Condition I has the biggest mass(B) Condition II has the biggest mass(C) Condition III has the biggest mass(D) I and II has the same weight and III is less(*E) All of them has the same massQ6. The following closed container, as shown in picture,

contains a mixture of oxygen ( ) and helium (’) gases at25 1C. Which one of the following situations would lead to thepartial pressure of the oxygen gas if the pressure of only oxygengas was measured?

Appendix II

As a cycling enthusiast, Onur does not miss the annual cyclingtournaments. After a long preparation time, he completes hiswork for this year’s tournament. Once doing necessary main-tenance of his bike, Onur waits for the tournament day

excitedly. Since the tournament will be international, therewill be high level of participation and he will have manychallenging opponents. The expected day finally comes andthe tournament begins but it consists of tough stages (Fig. 3).After a few miles while passing through wooded areas, Onur’sbicycle tire deflates. He loses the chance of racing as a result ofthis misfortune and he inflates the tire before leaving.Although he pumps the air from the same point of the rubber,tire inflation is the same in every point of the tire (Fig. 4).Which feature(s) of the gases do you think is the reason forthis situation?

What can be said about the motion/state of gas particles inthe deflated bicycle tire?

Compare the inside pressure of deflated bicycle tire with theoutside pressure.

Compare the inner pressures of the deflated tire exerted tothe sides and to the bottom, please explain the reason.

Can using up the energy of the gas particles in time andceasing their motion be the reasons of deflation of the bicycletire? Why?

Draw the distribution of the gas particles in the inflated andthe deflated bicycle tire.

What exists between the particles of gas in the bicycletire?

Fig. 3 Cycling tournament.

Fig. 4 Deflation of bicycle tire.


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Appendix III

Name of the cases Concept

Boiling of water on the mountainsAli likes to climb on the mountains in his free time. One day, during the camp, he realizes that waterboils faster on the mountain compared to the sea level and he decides to investigate the reason for this.Why do you think that water boils faster on the mountains?

Air pressure

Heating of water in the bottle covered with a balloonChildren put some water in a glass bottle and closes the mouth of the bottle with a balloon. They beginto heat the bottle slowly from its bottom. After a few minutes, they measure the circumference of theballoon. After water in the bottle is heated, what happened to the balloon? What is the reason for this?

Avagadro’s law

Air bagAyse experiences an accident while travelling, fortunately air bag in the car saves her life. Do you haveany idea about the working principle of air bags? Which properties should the gas filling in the airbaghave? Does the gas in the air bag exert the same pressure on all parts of the air bag?

Properties of gases

Cold and hot airMervan is curious about similarities and differences between cold and hot air and he decides to do anexperiment in order to find out the similarities and differences between cold and hot air. He closes theglass container tightly, in which there is air. He weighs it before heating this container and he alsoweighs it after heating. What can be said about the mass of the container after being heated?

Properties of gases

SodaWhen CO2 gas is dissolved in the liquid either by high pressure or low temperature, carbonated drinksoccur. When we open the bottle of soda and wait for a while, CO2 gas dissolved in liquid mixes into air.In this case, is there a difference in the mass of soda? Why?

Properties of gases

Bicycle tire (please see Appendix II) Gas behavior, gas pressure

Lung modelBreathing deeply can be associated with gas laws. When we breathe in, the muscles push the dia-phragm downwards and the chest broadens. What is the effect of this on the pressure inside andvolume of the lungs?When we take too much air in, how does it affect the elastic texture and the volume of the lungs? At themoment air taken in fills the lungs, if body temperature increases, what will happen to the volumeof lungs?

Boyle’s law, Avagadro’s lawand Charles’s law

Book

As seen from the figure, Ozge placed half of a pipette in the plastic food storage bag with a zipper.Mouth of the bag is sealed tight with a zipper. In order to prevent the air escaping from the plastic bag,fingers were placed at each side of the pipette. Afterwards, a book was placed on the bag and air isblowed into the storage bag by pipette. After a while, it is seen that the book rises. What causes thebook rise?

Partial pressure, gas pressure

Bottle covered with balloonChildren closes the mouth of a glass bottle, in which there is air, with a balloon that does not leak air inand out. First, they put the bottle in a cup that has hot water. After a while, what will be the shape of theballoon and why? Afterwards, they put the bottle in a cup full of ice in it. What will be the shape of theballoon after a while?

Charles’s law

Air bubblesAs it is known, divers use scuba tanks that have compressed air (nitrogen–oxygen) in them. When weexamine the actions of a diver swimming in the deep sea, we can observe that bubbles come out themouth of the diver and these bubbles rise upwards. While these bubbles are rising up, it is seen thatthe volume of these bubbles increase gradually and they become several times bigger than they were atthe beginning, Matter inside bubbles as well as chemical structure of matter do not change during theraise of bubbles. What may cause the change in the volume of the bubbles? (Assume that temperatureof sea water is constant at each point of the sea)

Boyle’s law


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References

Airasian P. W. and Walsh M. E., (1997), Constructivist cautions,Phi Delta Kappan, 78(6), 444–449.

Anderson C. W. and Smith E. L., (1987), Teaching science, inKoehler V. (ed.), The Educators’ Handbook, A research per-spective, New York: Longman, pp. 84–111.

Ayyıldız Y. and Tarhan L., (2013), Case study applications inchemistry lesson: gases, liquids, and solids, Chem. Educ. Res.Pract., 14(4), 408–420.

Azizoglu N., (2004), Conceptual change oriented instruction andstudents’ misconceptions in gases, Unpublished doctoral dis-sertation, Ankara: Middle East Technical University.

Benson D. L., Wittrock M. C. and Baur M. E., (1993), Students’preconceptions of the nature of gases, J. Res. Sci. Teach.,30(6), 587– 597.

Ben-Zvi R., Eylon B. and Silberstein J., (1982), Students vs.chemistry: A study of student conceptions of structure andprocess (Unpublished technical report), Rehovot, Israel:Weizmann Institute, Dept. of Science Teaching.

Name of the cases Concept

Vacuum pumpDilek wants to remove some of the air in the flask by using vacuum pump in the laboratory. Figure Ashows the flask without the vacuum pump being attached. In figure B flask is connected to the vacuumpump and some of the air in the flask is trapped in the vacuum pump. In figure C, process of eva-cuation of some air finishes and the mouth of the flask is closed tightly.

Dilek could not observe the evacuation process since she cannot see gas particles. She wants to showthe distribution of gases in the flasks by using dots. Could you please show these distributions in theflasks?

Properties of gases

Hot air balloonBalloon can fly in the atmosphere by using heated air or light gases such as helium, hydrogen. Howdoes heated air cause the balloon fly? What is the working principles of hot air balloons? If air in theballoon is cooled, what is the direction of the balloon? Is heated air in the flying balloon accumulatedat the upwards of the balloon? Why?

Gas behavior, gas pressure

Competition of gasesIn the competition where gases of He, H2, CH4, SO2 and SO3 race at the same conditions (same tem-perature and pressure), He and H2 gases finish the competition earlier, then CH4, SO2 and SO3 gasesfollow them respectively. What may be the reason for this? What type of information do we need toknow in order to decide the order of gases in the competition?

Diffusion of gases

Formation of white ringTwo friends, Tugba and Aysel like to measure the diffusion rates of two different gases, NH3 and HCl bythe help of apparatus below.

They put cotton that is soaked into concentrated NH3 solution at one end of the apparatus and theother cotton was put at the other end of the tube and this cotton was soaked in the concentrated HClsolution (note that solutions are at the same environment) after a while, NH3 and HCl gases meetsomewhere in the tube (temperature is constant during the experiment). Near to which end of the tubedo these gases meet? Why?(HCl = 36.5 g mol�1, NH3 = 17 g mol�1)

Diffusion of gases

Boiling teapotOzlem is watching her mother cook. Her mother wants Ozlem take care of the food for a while, butwhen food begins to boil, Ozlem realizes that lid of the saucepan bounces up and she closes the cookerin panic. In another day, during the boiling of water in the teapot, Ozlem sees that the lid of the teapotmoves similarly. She gets curious about this and wants to investigate the reason for this. What may bethe reason for this?

Gay-Lussac’s law


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Bilgin I., S- enocak E. and Sozbilir M., (2009), The effects ofproblem-based learning instruction on university students’performance of conceptual and quantitative problems in gasconcepts, Eurasia Journal of Mathematics, Science & TechnologyEducation, 5(2), 153–164.

Brook A., Briggs H. and Driver R., (1984), Aspects of secondarystudents’ understanding of the particulate nature of matter,Leeds: University Leeds, centre for Studies in Science andMathematics Education.

Brook A., Briggs H. and Driver R., (2003), Study of the evolutionof students’ initial knowledge during a teaching sequenceon gases at the upper secondary school level, J. Res. Sci.Teach., 30(6), 587–597.

Brotherton P. N. and Preece F. W. P., (1995), Science processskills: their nature and interrelationships, Research inScience & Technological Education, 13(1), 5–11.

Champagne A. B., Gunstone R. F. and Klopfer L. E., (1985),Cognitive structure and conceptual change, New York: Aca-demic Press.

Cho I. Y., Park H. J. and Choi B. S., (2000), Conceptual types ofKorean high school students and their influences on learning style,Paper presented at the Annual Meeting of the National Associa-tion for Research in Science Teaching, New Orleans, LA.

Cobern W. W., Schuster D., Adams B., Applegate B., Skjold B.,Undreiu A., Loving C. C. and Gobert J. D., (2010), Experi-mental comparison of inquiry and direct instruction inscience, Research in Science & Technological Education,28(1), 81–96.

Çakır O. S., (2002), The development, implementation, and evaluationof a case method in science education, Unpublished doctoraldissertation, Ankara: Middle East Technical University.

Çam A., (2009), Effectiveness of case-based learning instruction onstudents’ understanding of solubility equilibrium concepts,Unpublished doctoral dissertation, Ankara: Middle EastTechnical University.

De Berg K. C., (1995), Student understanding of the volume,mass, and pressure of air within a sealed syringe in differentstates of compression, J. Res. Sci. Teach., 32(8), 871–884.

DeYoung S., (2003), Teaching strategies for nurse educators,Upper Saddle River, NJ: Prentice Hall.

Driscoll M.P., (2005), Psychology of learning for instruction,Toronto: Allyn and Bacon.

Frerichs V. A., (2012), ConfChem Conference on Case-BasedStudies in Chemical Education: Use of Case Study for theIntroductory Chemistry Laboratory Environment, J. Chem.Educ., 90(2), 268–270.

Gabel C., (1999), Using case studies to teach science, NationalAssociation for Research in Science Teaching National Con-ference, Boston, Massachusetts.

Gabel D. L., Samuel K. V. and Hunn D., (1987), Understandingthe particulate nature of matter, J. Chem. Educ., 64, 695–697.

Gallucci K., (2006), Learning concepts with cases, J. Coll. Sci.Teach., 36 (2), 16–20.

Gallucci K., (2007), The case method of instruction, conceptual change,and student attitude, Unpublished doctoral dissertation, Raleigh:North Carolina State University.

Gay L. R. and Airasian P., (2000), Educational Research: Compe-tencies for analysis and application, New Jersey: Prentice-HallInc.

Geban O., As-kar P. and Ozkan I., (1992), Effects of computersimulated experiments and problem solving approaches onhigh school students, J. Educ. Res., 86, 5–10.

Geban O., Ertepınar H., Yılmaz G., Altın A. and S- ahbaz F.,(1994), Bilgisayar destekli egitimin ogrencilerin fen bilgisibas-arılarına ve fen bilgisi ilgilerine etkisi. I.Ulusal FenBilimleri Egitimi Sempozyumu: Bildiri Ozetleri Kitabı, 1–2,9 Eylul Universitesi, zmir.

Gilbert J. K., Osborne R. J. and Fensham P. J., (1982), Children’sscience and its consequences for teaching, Sci. Educ., 66,623–633.

Givry D., (2003) Study of the evolution of students’ initialknowledge during a teaching sequence on gases at theupper secondary school level (15 years old, grade 10), inthe Proceedings of ESERA Summer-school, Radovljica(Slovenie).

Griffiths A. and Preston K., (1992), Grade-12 students’ miscon-ceptions relating to fundamental characteristics of atomsand molecules, J. Res. Sci. Teach., 29, 611–628.

Haidar A. H. and Abraham M. R., (1991), A comparision ofapplied and theoretical knowledge of concepts based on theparticulate neture of matter, J. Res. Sci. Teach., 28(10),919–938.

Harlen W., (1999), Purpose and procedures for assessingscience process skills, Assessment in Education, 6, 129–144.

Hwang B. T., (1995), Students’ conceptual representations of gasvolume in relation to particulate model of matter, PaperPresented at the Annual Meeting of the National Associationfor research in Science Teaching, San Francisco, CA.

:Ipek I., (2007), Implementation of conceptual change oriented

instruction using hands on activities on tenth grade students’understanding of gases concept, Unpublished master’s thesis,Ankara: The Middle East Technical University.

Jonassen D. H., (1994), Thinking technology, Educ. Technol.,34(4), 34–37.

Kautz C. H., Heron P. R. L., Loverude M. E. and McDermott L.C., (2005a), Student understanding of the ideal gas law, PartI: a macroscopic perspective, Am. J. Phys., 73(11) 1055–1063.

Kautz C. H., Heron P. R. L., Shaffer P. S. and McDermott L. C.,(2005b), Student understanding of the ideal gas law, Part II:a microscopic perspective, Am. J. Phys., 73(11) 1064–1071.

Koballa T. B. and Glynn S. M., (2007), Attitudinal and Motiva-tional constructs in science learning, in Abell S. K. andLederman N. G. (ed.), Handbook of Research on ScienceEducation. Part 1, Mahwah, New Jersey, London: LawrenceErlbaum Associates, Publishers, pp. 75–102.

Lee O., Eichinger D. C., Anderson C. W., Berkheimer G. D. andBlakeslee T. D., (1993), Changing middle school students’conceptions of matter and molecules, J. Res. Sci. Teach.,30(3), 249–270.

Lin H. S., Cheng H. J. and Lawrenz F., (2000), The assessment ofstudents and teachers’ understanding of gas laws, J. Chem.Educ., 77(2), 235–238.


Publ

ishe

d on

06

Nov

embe

r 20

14. D

ownl

oade

d on

07/

12/2

014

00:0

3:57




Lonning R. A., (1993), Effects of cooperative learning strategieson students verbal interactions and achievement duringconceptual change instruction in 10th grade general science,J. Res. Sci. Teach., 30(9), 1087–1101.

Mas C. J. F., Perez J. H. and Harris H. H., (1987), Parallelsbetween adolescents’ conception of gases and history ofchemistry, J. Chem. Educ., 64(7), 616–618.

Mayer R., (1999), Designing instruction for constructivist learn-ing, in Reigeluth C. M. (ed.), Instructional-design theories andmodels: Vol. 2. A new paradigm of instructional theory, Mah-wah, NJ: Lawrence Erlbaum Associates, pp. 141–160.

Mayo J. A., (2002), Case-based instruction: a technique forincreasing conceptual application in introductory psychology,J. Constr. Psychol., 15, 65–74.

Mayo J. A., (2004), Using case-based instruction to bridge thegap between theory and practice in psychology of adjust-ment, J. Constr. Psychol., 17, 137–146.

Niaz M., (2000), Gases as idealized lattices: a rational recon-struction of students’ understanding of the behavior ofgases, Sci. Educ., 9, 279–287.

Novick S. and Nussbaum J., (1978), Junior high school pupils’understanding of the particulate nature of matter: an inter-view study, Sci. Educ., 62(3), 273–281.

Novick S. and Nussbaum J., (1981), Pupils’ understanding ofthe particulate nature of matter: a cross age study, ScienceEducationSci. Educ., 65(2), 187- 196.

Nussbaum J., (1985), The particulate nature of matter in thegaseous phase, in Driver R., Guesne E. and Thiberghien, A.(ed.), Children’s Ideas in Science, Philadelphia: Open Univer-sity Press, pp. 124–144.

Okey J. R., Wise K. C. and Burns J. C., (1982), Test of IntegratedProcess Skills (TIPS II). Athens: University of Georgia, Depart-ment of Science Education.

Peterson P. L., (1979), Direct instruction: effective for what andfor whom, Educ. Leadership, 37(1), 46–48.

Pintrich P. R., Marx R. W. and Boyle R. A., (1993), Beyond coldconceptual change: the role of motivational beliefs andclassroom contextual factors in the process of conceptualchange, Rev. Educ. Res., 63(2), 167–169.

Pintrich P. R., Smith D. A. F., Garcia T. and McKeachie W. J.,(1991), A Manual for the use of the Motivated Strategies forLearning Questionnaire (MSLQ), Ann Arbor, MI: NationalCenter for Research to Improve Postsecondary Teachingand Learning, The University of Michigan.

Posner G. J., Strike K. A., Hewson P. W. and Gertzog W. A.,(1982), Accommodation of a scientific conception: toward atheory of conceptual change, Sci. Educ., 66(2), 211–227.

Richmond G. and Neureither B., (1998), Making case for cases,Am. Biol. Teach., 60(5), 335–340.

Rollnick M. and Rutherford M., (1990), African primary schoolteachers: What ideas do they hold on air and air pressure?,Int. J. Sci. Educ., 12(1), 101–113.

Rybarczyk B., Baines A. T., McVey M., Thompson J. T. andWilkins H., (2007), A case-based approach increases studentlearning outcomes and comprehension of cellular respira-tion concepts, Biochem. Mol. Biol. Educ., 35(3), 181–186.

Sanger M. J., Phelps A. J. and Fienhold J., (2000), Using acomputer animation to improve students’ conceptual under-standing of a can-crushing demonstration, J. Chem. Educ.,77(11), 1517–1520.

Saral S., (2008), The effect of case-based learning on tenth gradestudents’ understanding of human reproductive system and theirperceived motivation, Unpublished master’s thesis, MiddleEast Technical University, Ankara.

Sere M. G., (1986), Children’s conception of the gaseous stateprior to teaching, Eur. J. Sci. Educ., 8(4), 413–425.

She H. C., (2002), Concepts of a higher hierarchical level requiremore dual situated learning events for conceptual change: astudy of air pressure and buoyancy, Int. J. Sci. Educ., 24(9),981–996.

Stavy R., (1988), Children’s conception of gas, Int. J. Sci. Educ.,10(5), 553–560.

Stavy R., (1990), Children’s conceptions of changes in the stateof matter: from liquid (or solid) to gas, J. Res. Sci. Teach.,27(3), 247–266.

Sungur, S (2004), The implementation of problem based learningin high school biology courses, Unpublished PhD thesis,Turkey: Middle East Technical University.

Taber K. S., (2008), Exploring student learning from a construc-tivist perspective in diverse educational contexts, Journal ofTurkish Science Education, 5(1), 2–21.

Thompson J. and Soyibo K., (2002), Effects of lecture, teacherdemonstrations, discussion and practical work on 10thgraders’ attitudes to chemistry and understanding of elec-trolysis, Research in Science & Technology Education, 20(1),25–37.

Wandersee J. H., Mintzes J. J. and Novak J. D., (1994), Researchon alternative conceptions in science, in Gabel D. L. (ed.),Handbook of Research on Science Teaching and Learning, NewYork: Macmillan, pp. 177–210.

Wassermann S., (1994), Introduction to case method teaching: Aquide to the galaxy, New York: Teachers College Press.

Woods D., (1994), Problem-based Learning: How to Gain the Mostfrom PBL, Hamilton: W. L. Griffin Printing Limited.


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The effect of case-based instruction on 10th grade students' understanding of gas concepts