Effect of Cooperative Learning Strategies on Students' Understanding ...

BURCIN ACAR and LEMAN TARHANj

EFFECT OF COOPERATIVE LEARNING STRATEGIES ON STUDENTS’ UNDERSTANDING OF CONCEPTS IN ELECTROCHEMISTRY Received: 23 June 2005; Accepted: 15 May 2006 ABSTRACT. The present study was conducted to investigate the degree of effectiveness of cooperative learning instruction over a traditional approach on 11th grade students’ understanding of electrochemistry. The study involved forty-one 11th grade students from two science classes with the same teacher. To determine students’ misconceptions concerning electrochemistry, the Electrochemistry Concept Test consisting of 8 openended and 12 multiple-choice questions was used as a pre-test and some students were interviewed. According to the results, twenty-four misconceptions (six of them initially identified) about electrochemistry were identified. The classrooms were randomly assigned to a control group (traditional instruction, 21 students) and an experimental group (cooperative learning based on a constructivist approach, 20 students). After instruction, the same test was administered to both groups as a post-test. The results from the t-test indicated that the students who were trained using cooperative learning instruction had significantly higher scores in terms of achievement than those taught by the traditional approach. According to the post-test and interviews, it was also found that instruction for the cooperative group was more successful in remediation of the predetermined misconceptions. KEY WORDS: chemistry education, constructivism, cooperative learning, electrochemistry, remediation of misconception

Misconceptions can seriously affect students’ performance and learning ability in chemistry and they are obstacles to the acquisition of scientific concepts. In the past 25 years most research in the field of chemical education has focused on the determination of student misconceptions about scientific topics which are difficult to understand such as the gas laws, chemical equilibrium, acidsYbases, the mol, atoms and molecules, the state of matter, physical and chemical changes and chemical bonding. Electrochemistry is one of these topics that students commonly find problematic and in which they develop a wide range of misconceptions. In Western Australia, Garnett, Garnett & Treagust (1990a, 1990b) studied grade 12 students’ understanding of electrochemistry, and described misunderstandings and misconceptions with the aim of improving the science curriculum. The most important reasons were given as subject knowledge, inadequate prerequisite knowledge, students’ interpretations of language, the use of multiple definitions and models, j

Author for correspondence.

International Journal of Science and Mathematics Education (2007) 5: 349Y373 # National Science Council, Taiwan 2006

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BURCIN ACAR AND LEMAN TARHANA

and the use of concepts and algorithms in a rote fashion without any attempt to understand fully and analyse the problem. Garnett & Treagust (1992a, 1992b) interviewed high school students to investigate their understanding of electrochemistry. They found that students commonly had misconceptions about identifying anodes and cathodes and their functions such as: Fthe anode is negatively charged and because of this it attracts cations,_ Fthe cathode is positively charged and because of this it attracts anions,_ Fthe anode is positively charged because it has lost electrons,_ Fthe cathode is negatively charged because it has gained electrons,_ and Fan inert electrode is not necessary._ They also had misconceptions concerning how the electric current occurs in electrochemical cells such as: Felectric current only occurs by movement of electrons,_ Felectrons enter the electrolyte at the cathode, move through the electrolyte and emerge at the anode to complete the circuit;_ and with the function of a salt bridge such as Fthe salt bridge supplies electrons to complete the circuit and assists the flow of current (electrons) because positive ions in the bridge attract electrons from one half-cell to another._ Sanger & Greenbowe (1997a) replicated Garnett & Treagust’s interviews on electrochemical and electrolytic cells and also concentration cells to identify students’ common misconceptions. Together with the same misconceptions in the study of Garnett & Treagust (1992a, 1992b), they reported additional misconceptions. They indicated that students were failing to explain the formation of electric current and to determine the nature of an anode and cathode. The common students’ misconceptions about electrochemical cells were: Fthe identity of the anode and cathode depends on the physical placement of the half-cells;_ Fanodes, like anions, are always negatively charged; cathodes, like cations, are always positively charged;_ Felectrons can flow through aqueous solutions without assistance from the ions;_ Fonly negatively charged ions constitute a flow of current in the electrolyte and the salt bridge._ Sanger and Greenbowe also found that students could not explain the working principle of the electrolytic cell; Fif identical electrodes are connected to the battery, the same reactions would occur at each electrode in an electrolytic cell and when two or more oxidation or reduction halfreactions were possible, there was no way to determine which reaction would occur._ In the other research, Sanger & Greenbowe (1999) analysed college chemistry textbooks as sources of misconceptions and errors in electrochemistry. They state that the sources of misconceptions on electron flow in electrolytic solution and salt bridge were a result of misleading statements used by instructors and textbooks, and a lack of relationship

COOPERATIVE LEARNING IN ELECTROCHEMISTRY

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between concepts. Thompson & Soyibo (2002) reported that high school students ranked electrolysis concepts as being the most difficult to understand in the subject of chemistry and they had a poor understanding of electrolysis. If all of this research is examined, it can be seen that there are limited studies on remediation of misconceptions about electrochemistry. Nonetheless, some researchers offered a conceptual change approach (Sanger, 2000), teaching models (Hudle & White, 2000), and computer animations (Sanger & Greenbowe, 1997b; Burke, Greenbowe & Windschitl, 1998; Sanger, 2000) to remedy misconceptions on electrochemistry. Educators in the field of science education conducted studies using various learning theories to remedy misunderstandings and misconceptions, and to increase students’ levels of learning achievement. Several researchers (Rogan, 1988; Basili & Sanford, 1991; Hameed, Hackly´ng & Garnett, 1993; Ebenezer & Gaskell, 1995; Nist & Holschuh, 2000; Sanger, 2000) used a constructivist learning approach to change students’ conceptions and to help students to understand chemical concepts. According to the constructivist approach, the most important factor that affects learning is students’ existing knowledge. Constructivism helps to explain why students bring misconceptions to chemistry classes and where these misconceptions come from. It also emphasizes the importance of the flow of knowledge between teachers and students. Bodner (1986) summarized the constructivist approach in a single statement: Knowledge is constructed in the mind of the learner. Therefore, students need to construct new information by using their existing knowledge and experiences. If the new information is consistent with their existing knowledge, it can be assimilated; but if the new information contradicts it, the knowledge must be changed to accommodate the new information (Resnick, 1983). Hodson (1996) summarized the main four steps of the constructivist approach: (1) identify students’ ideas and views, (2) create opportunities for students to explore their ideas, (3) provide stimuli for students to develop, modify and, where necessary, change their ideas and views, and (4) support their attempts to re-think and reconstruct their ideas and views. Researchers such as Driver (1981), Hewson & Hewson (1984), Driver & Oldham (1986), Osborne & Freyberg (1985), Hand & Treagust (1991), Strike & Posner (1992), Chambers & Andre (1997), and Hodson (1996) suggested constructivism as a form of teaching which encourages a change from misconceptions to scientifically acceptable concepts. Construction of the knowledge occurs best in an active learning environment. Active learning methods such as cooperative learning encour-

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ages students to be active participants in the construction of their own knowledge during the learning process (Webb, Troper & Fall, 1995; Lonning, 1993). The benefits of cooperative learning for students’ social and academic skills have been well documented by researchers (Jones & Steinbrink, 1989; Jordan & Le Metaias, 1997; Slavin, 1996; Towns & Grant, 1997). Johnson, Johnson & Holubec (1993) defined cooperative learning as involving three or more children who were working together in a group in order to maximize their own and each other’s learning. Johnson & Johnson (1987) indicated that if cooperative learning were used more widely and more often, students would learn to be more scientific, come to feel better about themselves as science students, and to have a more healthy attitude toward the acceptance of differences in their classmates. According to Towns & Grant (1997) cooperative learning activities were consistent with the idea that students must actively process information to learn it in a meaningful way. In their research, Basili & Sanford (1991) investigated small cooperative group work incorporating appropriate focusing tasks as a strategy for fostering conditions for conceptual change and found that students in a cooperative group had a significantly lower proportion of misconceptions than students in the control group. Based on the literature it can be said that cooperative learning based on the constructivist approach is effective for remediation of misconceptions. METHODOLOGY Purpose According to the research, students around the world have lots of misconceptions concerning electrochemistry. But, studies on the remedying of misconceptions are limited. As mentioned by Bodner (1986), students’ misconceptions are remarkably resistant to instruction and learning. For this reason, the present study aimed to identify answers to the following research questions: 1. What conceptions related to electrochemistry do 11th grade students have? 2. What is the effect of cooperative learning based on constructivism over a teacher centered traditional approach on 11th grade students’ understanding of electrochemistry? 3. What are students’ and teacher’s perceptions about cooperative learning instruction?


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Sample Students in high school science classes learn chemistry over three years in Turkey. The Turkish chemistry syllabus contains electrochemistry under the unit of Oxidation and Reduction Reactions in the first semester of the third year (11th grade). According to the content sequence of the unit required by the Ministry of National Education (MEB), students learn redox reactions, half-equation, oxidationYreduction, oxidantYreductant, oxidizedYreduced, elements’ activity before studying the subject of electrochemistry. This study was carried out at the beginning of the second semester of the third year. Prior to treatment, the teacher was trained about active learning and its applications. The subjects of the study consisted of fortyone 11th grade students (17 years of age) from two science classes in a high school in Izmir, which is a big city in Turkey. Students in both classes were taught the unit of Oxidation and Reduction Reactions in the traditional manner at the beginning of the previous semester. Before the research study, one of the classes was randomly assigned to the experimental group (N = 20) while the others formed a control group (N = 21). Students in the experimental group were stratified and randomly assigned into their cooperative groups by their teacher according to their achievement on the pre-test and their social skills. While students in the control group were taught with a teacher-centered traditional approach, students in the experimental group were trained with cooperative learning instruction based on a constructivist approach. All the students from the two science classes were taught by the same chemistry teacher. The teacher had ten years experience. The teacher, who implemented cooperative learning in the experimental group, underwent training on appropriate use of the materials before the implementation in order to be sure that the material was used as planned. Because she was experienced on active learning, she adapted the study easily. The teacher was informed about the misconceptions related to electrochemistry and told about which activities had been developed to prevent which misconceptions. She was required to follow the content sequence and to strategically ask questions, which were prepared for the construction of knowledge. Instruments Electrochemistry Concept Test The test, composed of eight open-ended and twelve multiple-choice items, was developed by researchers and given to the students before and

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after the treatment to identify conceptual difficulties and their understanding about electrochemistry. Items were related to: (a) reactions in electrochemical cells, (b) constitution of electrical current, (c) identification of the anode and cathode and their charges, (d) functions of a salt bridge, (e) functions of metal rods, (f) function of a voltmeter, (g) cell potential, (h) a half-cell and standard hydrogen electrode and (i) electrolysis. Some selected examples of the test items are given in the Appendix. Prior to the development of the tests items, the content boundaries were defined and instructional objectives were developed by researchers. Tests items were constructed according to the objectives and by considering misconceptions identified in the literature. The content of the tests was validated by a group of experts in chemistry education and high school chemistry teachers. In addition, the test was piloted with one hundred and fifty 11th grade students for reliability. After the item analysis, three questions were eliminated, because their discrimination indexes were below 0.3. The reliability coefficient (KR 20) of the test was found to be 0.86 after the pilot study. Interviews Before the treatment, 20-minute semi-structured interviews were carried out with ten students from each group to ensure the reliability of the study and also to gather more information about students’ conceptions of electrochemistry. These students were those whose responses were the most irrelevant and full of misconceptions in the pre-test. During the interviews, researchers asked students to explain the reasons for their answers on the test. In this way, students’ misconceptions were identified more definitely. Following the treatment, volunteer students from the experimental group and the teacher were individually interviewed about the effectiveness of cooperative learning instruction based on constructivism. During the semistructured interviews, students were asked the following questions: 1. What are the effects of working in a cooperative group on your behaviour, interaction and learning achievement? 2. What do you think about the teacher’s role during the learning period? 3. What is your opinion about the activities used during the learning period? Treatment This study was related to electrochemistry. The concepts of redox reactions, half-equation, oxidationYreduction, oxidantYreductant, oxidizedYreduced


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and elements’ activities, which are bases for electrochemistry, formed the topics for a 45 minute preparatory lesson given by the teacher to remind students of these subjects and also to remedy their misconceptions. To determine students’ understandings related to electrochemistry (electrochemical cells, cell potential, electrolytic cell) the electrochemistry concept test was applied before the treatment. The teacher began to teach electrochemistry with a traditional approach in the control group, and with cooperative learning in the experimental group. The following learning objectives were taken into consideration during treatment in both groups:

Explain the concepts of electrode, cathode and anode. Classify the reactions that occur in the cells as oxidation and reduction. Interpret the function of a salt bridge. Interpret the function of metal rods. Explain the working principle of electrochemical cells. Write half-cell reactions. Write the overall electrochemical cell reaction. Calculate standard cell potential. Explain the working principle of electrolytic cell. Predict the products of electrolysis. Connect redox reactions, electrochemical cells and electrolysis with daily life.

The instructions were given during 11 course hours (four course hours per week and 45 minutes for each course) to both groups by the same chemistry teacher. Cooperative Learning Instruction It is clear that just placing students in groups and expecting them to work together doesn’t promote cooperation and learning. In this study, cooperative learning instruction was used in the experimental group. This instruction focused on constructivism and aimed to help students recognize the conflict between their existing concepts and scientific concepts, and to provide them with the opportunity to learn the correct ones. For this reason, materials used in this study were prepared for construction of knowledge in students’ minds, and students were helped and encouraged to discuss during the learning process. Before the treatment, 20 students were stratified by their teacher and randomly assigned into their cooperative groups according to their achievement on the pre-test and their social skills. There were four

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groups with five students each. Before the beginning of the treatment, the teacher gave information about learning objectives, the instruction process, rules of working in a cooperative group, roles, and assessment strategies (Johnson & Johnson, 1999). Students in the groups were encouraged to decide who would be the leader, recorder, timekeeper and reflector. All the activities were completed by students under the guidance of the teacher. While students were discussing in their small groups, the teacher visited all the groups and asked some guiding questions to lead students in an appropriate direction. All the cooperative groups prepared their own reports after the activities were completed and presented. In this way, the teacher assessed whether they had acquired the learning objectives. The teacher assessed the group process during the lesson by asking some questions such as BWhat are you doing?,^ BWhy are you doing it?,^ BHow will it help you to understand the subject?,^ and BWhy are you researching it?^ The following scheme gives some detailed information about treatment in the experimental group.

To arouse students_ interest, a brainstorming activity about Galvani_s observations on trembling frog_s leg connected to Zn and Cu metals was done in cooperative groups. ,

To clarify this brainstorming activity and to introduce students to electrochemical cells:

A hands-on experimental activity related the constitution of electrical energy via potential differences between a copper rod and some metal rods such as Zn, Sn, Mg, or Ni immersed binary into a fruit like a lemon, apple, and orange was performed. ,

To teach standard conditions for the international validity and events in an electrochemical cell:

A computer animation illustrating constitution of electrical energy was shown. Previously weighed zinc and copper rods were immersed in a cup with 1M HCl solutions under the standard conditions (25-C and 1 atm pressure) and then rods were connected to the lamp with an electrical wire.


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To teach the events that occurred in the cell:

A computer animation which illustrates the working principle of electrochemical cells step by step was started. The following steps were shown: Zinc and copper metals were immersed into ZnSO4 and CuSO4 solutions respectively. The rods were connected via a conductive wire. Cups were connected to each other with a salt bridge, which included concentrated electrolytic NaSO4 solution.After all the steps a break was given and discussion was started. The teacher explained some concepts such as electrolyte, electrode, anode, cathode, half-cell, and salt-bridge in appropriate steps. Students discussed the following concepts and subjects: redox reactions, salt bridge_s function, electron flow, ion flow, continuity of conductivity, lighting up the lamp, changing of metals surface, and metal_s charges. ,

To teach the concepts of potential difference, electromotive force-cell potential (E) and standard cell potential (E0):

The teacher stimulated the flow of electrons from anode to cathode to cause a flow of water over a waterfall from high potential energy to low potential energy and explained potential differences, cell potential, standard cell potential (E0); standard hydrogen electrode (SHE), the function of platinum electrode, reasons for SHE acting as a cathode or an anode, electrons_ and ions_ flow, charge of anode and cathode. ,

To teach batteries:

Hands-on experimental activity about the working principles of Volta batteries was carried out and then students were required to research Lechlanche, Lead-acid, Alkaline, Nickel-Cadmium and fuel cells from use of library materials and sources on the Internet. ,

To introduce the electrolytic cell:

A brainstorming activity was done. Students asked if most metals were found as a compound in nature, and how gold and silver jewelry, copper wires or aluminum covered cables were made.

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,

To teach the working principle of an electrolytic cell:

A group discussion was started. Students were asked under which conditions zinc metal (not silver metal) could be collected on the cathode, the reason for the relation between E0cell and the spontaneous occurrence of a reaction was commented on and the transformation of electrical energy to chemical energy, namely, electrolysis was discussed. ,

To teach the differences between electrochemical cells and electrolytic cell:

A computer animation was shown relating the events that happen in the electrolytic cell and differences between the electrochemical cells were discussed in the groups. After the group discussion, electrolysis of water, the electrolysis of molten sodium chloride and its aqueous solution and electroplating was given to students as research work. Traditional Instruction The control group was taught with a teacher-centered traditional didactic lecture format. Teaching strategies were dependent on teacher expression without consideration for student misconceptions. The same content was taught in the cooperative group and the learning objectives were the same. In contrast with the cooperative group, the first group of students were required to use their textbooks; students were passive participants and rarely asked questions; they did not benefit from the library or internet sources; activities such as computer animations or brainstorming were not used; generally the teacher wrote the concepts on the board and then explained them; students listened and took notes as the teacher lectured on the content. The following scheme gives some detailed information about the treatment in the control group. The teacher explained how to produce electrical energy and determined electrochemical cells by drawing a Zn-Cu cell on the board. The concepts of electrode, electrolyte, anode, cathode, electrolytes, salt bridge, electron flow and ion flow and oxidation and reduction reactions in the cells were explained by the teacher, and some sample questions were solved.


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To teach the concepts of potential difference, of an electromotive force-cell potential (E) and standard cell potential (E0):

The teacher used the same Zn-Cu cell and explained that electrons flowed from the anode to cathode and this flow produces the potential differences. The teacher presented the standard cell potential (E0) and taught how to calculate it. ,

To teach the standard hydrogen electrode (SHE), and the function of a platinum electrode:

The teacher drew Zn-SHE on the board and showed the electrons_ flow and explained the function of a platinum electrode and the reasons for SHE acting as a cathode or an anode. Some example questions were solved. ,

To teach about batteries:

The teacher gave the sample of Volta batteries and explained their working principle. She explained the other type of batteries such as Lechlanche, Lead-acid, Alkaline, Nickel-Cadmium and fuel cells and their usage areas. ,

To teach the working principle of an electrolytic cell:

The teacher explained the differences between electrochemical cells and electrolytic cells by using the example of electrolysis of water. The electrolysis of molten sodium chloride and its aqueous solution and electroplating was also explained to the students.

Data Analysis Data from the tests were analysed using the student t-tests. For data analysis, the multiple-choice questions were classified as correct (3 points), incorrect (0 points) and blank (0 points). The responses for the open-ended items were categorized in four ways as described below: correct, partially correct, incorrect, and no response.

360 Score Correct (3 points)

Partially correct (2 points)

Incorrect (1 point) No response (0 points)


Description The response reflects learning objectives clearly and in detail. The student shows a depth of understanding of the ideas related to the topic and understands important relationships. The response is satisfactory, contains some detail, is vague or not well developed, and includes some misconceptions or some inaccurate information. The response shows apparent gaps in the student’s knowledge and understanding of the topic. The response is poor, lacks clarity, and contains misconceptions, inaccurate or irrelevant information. Answer area was left blank.

Each of the answers was evaluated by researchers, two expert tutors and the teacher; scores were compared and discussed until an agreement was reached. To compare students’ achievement in both groups, data from the pre-test and post-test were analysed using the student’s t test. During each interview, the student-interviewer conversations were recorded on audio cassettes and then were analysed by researchers. Results The student’s t-test was used to compare pre- and post-test scores. Independent t-test analysis showed that there was no statistically significant difference between the mean scores of the experimental and the control groups with respect to (t = 0.199, p 9 0.05) the pre-test. The mean scores of the experimental group and control were 51.7% and 50.9%, respectively (Table I). According to the results from the pre-test and also interviews with ten students from each group, 24 misconceptions were identified. While 18 of them were similar to misconceptions reported previously, 6 of them were different. Similar misconceptions were concerned with subjects such as the measurement of standard cell potential, flow of electrons, function of a salt bridge, charge of an anode and cathode, applied voltage in electrolysis, the function of an inert electrode and the role of water during electrolysis. Different misconceptions determined in this study dealt with the flow of protons, function


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TABLE I Comparison of experimental and control groups according to t-test results Experimental group (N=20)

Control group (N=21)

Groups

M

S

M

S

t

p

Pre-test Post-test

51.7 88.6

16.60 7.42

50,9 55,3

21.14 16.98

0.199 18.75

0.843 0.000

of electrodes, movement of ions, cell potential, electrolysis of salts in the aqueous and molten situations, and structure and function of a battery in the electrolytic cell. As seen in Table II, the identified misconceptions with a higher percentage were focused on the constitution of electrical current, identification of an anode and cathode and their charge, and prediction of the products of electrolysis. The same test was administered to both groups after instruction as a post-test and a significant difference was found between the mean scores of the students who used instruction based on the constructivist approach and those taught by traditional instruction. The mean score of the control group was 55.3 and that of the experimental group was 88.6 on the posttest. The students in the experimental group scored significantly higher than those in the control group. The results showed also that students in the control group still had misconceptions (Table II). The mean scores of students increased at the rate of 35.9% in the experimental group and only 4.4% in the control group. After the treatment, the teacher and eleven volunteers from the experimental group were individually interviewed about the effectiveness of instruction based on constructivism in the cooperative groups. The teacher suggested that there is a need for some newly developed materials based on constructivism including active learning methods and strategies. She also expressed the idea that instruction based on constructivism was very effective for learning electrochemistry and, especially, that computer animations made the lesson more interesting and meaningful, and helped students’ understanding of electrochemical concepts. Students’ learning capacity and ability for working in a group were also increased. She expressed the idea that passive, silent and shy students had changed during the lessons and they had begun to participate in the learning process, expressing their opinions and making connections between old and new concepts.

Electrical Current Electrons enter the electrolyte at the cathode, move through the electrolyte and emerge at the anode to complete the circuit. Protons and electrons flow in the opposite directions to constitute an electric current.* Electrons can flow through aqueous solutions without assistance from the ions. Only negatively charged ions constitute a flow of current in the electrolyte and the salt bridge. Identify Cathodes and Anodes and Their Charges The anode is negatively charged and because of this it attracts cations. The cathode is positively changed and because of this it attracts anions. Anodes, like anions, are always negatively charged; cathodes, like cations, are always positively charged. The anode is positively charged because it has lost electrons. The cathode is negatively charged because it has gained electrons. The identity of the anode and cathode depends on the physical placement of the half-cells.

Student misconceptions

5 0 0 10

15

5 0 0 5

65 75 30 40

85

35 30 35 70

%

%

24 42.8 71.4

42.8

76.2

46.7

24

76.2

71.4

%

Pre-test

Post-test

Pre-test

18 24 32

24

38

38

12

52,4

69.2

%

Post-test


Experimental group (N=20)

Percentages of students’ misconceptions determined at the pre- and post-tests in experimental and control groups

TABLE II

362 BURCIN ACAR AND LEMAN TARHANA

In electrochemical cell oxidation occurs at the anode and reduction occurs at the cathode, while in electrolytic cells oxidation occurs at the cathode and reduction occurs at the anode. Function of Metal Rods Metal rods only act as an electron carrier during redox reaction and so there will be no change in the electrodes physical structure.* No reaction will occur if inert electrodes are used. Inert electrodes can be oxidized or reduced. Function of a Salt Bridge The salt bridge supplies electrons to complete the circuit. The salt bridge assists the flow of current (electrons) because positive ions in the bridge attract electrons from one half-cell to the other cell. Potential Differences and Cell Potential In electrochemical cells, as the attraction forces between anions and cations affect ions velocity to electrodes, different potentials are read when different solutions are used in the cells.* Protons and electrons flowing in opposite directions cause a potential difference between the two ends of wire.* Half-cell A standard half-cell is not necessary. Electrolysis In electrolytic cells the polarity of the terminals of the applied voltage has no effect on the site of the anode and cathode. Water does not react during the electrolysis of an aqueous solution.

10

10

5 5 0 0

5

0

0 20 10

75

85

95 45 45 35

90

70

20 85 70

71.4

86

24

52.4

81

38 38

81 38

71.4

76.2

42.8

52.4

10

24

76.2

18 24

34.2 24

28

42.8


363

% 5 15 10 0

% 85 85 80 70

Student misconceptions

The same products are produced in both aqueous and molten situation of salt electrolysis.* There is no association between the calculated e.m.f. of an electrolytic cell and the magnitude of the applied voltage. In electrolytic cells with identical electrodes connected to the battery, the same reactions will occur at each electrode. It is not important which sides of the battery are connected to the electrodes, as the same reactions occur at the electrodes.*

*Firstly defined misconception in the study

Post-test

Pre-test

Experimental group (N=20)

(continued)

TABLE II

52.4

81

81

75.2

%

Pre-test

24

75.2

75.2

62.3

%

Post-test


364 BURCIN ACAR AND LEMAN TARHANA


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Students in the experimental group generally liked the instruction linked to working in a group, believed especially that the computer animations helped them to understand electrochemical cells and electrolytic cells better, and wanted the course to be like this rather than having teacher-centered instruction in the future. Most students indicated that working in the group provided opportunities to listen to each other, share ideas, and form new friendships. They were generally satisfied with the teacher’s behaviour. They emphasized that it was good that the teacher visited their group to monitor and guide their work and that it encouraged them to participate in group work. They admitted that their motivation increased with increasing interaction with the teacher. They expressed the idea that the classroom climate was conducive for learning, that animations and experiments were useful in their understanding of electrochemistry, and the activities encouraged them to discuss with their classmates. Students believed that they had learned about electrochemistry beyond what the textbooks taught and had begun to connect their knowledge with daily life. Discussion The present study was an investigation of the effect of cooperative learning on students’ understanding of electrochemistry. For this purpose, a pre-test was administered to the 11th grade students and interviews were conducted before the treatment to identify their prior knowledge and understandings of electrochemistry. The results showed that students in both groups had misconceptions on a large scale (Table II). These identified misconceptions of Turkish students were of a similar proportion to the other countries in the world. On the other hand, while some misconceptions reported by Garnett & Treagust (1992a, 1992b), and Sanger & Greenbowe (1997a) were not observed, six new misconceptions were identified in this study. As seen above, all students in this study did not assimilate electrochemistry sufficiently. The research on cooperative learning showed that the cooperative setting provided students with the opportunities to engage in higher-order thinking skills and in processes of shared thinking which helped them to not only gain a better understanding but also to build on their contributions to develop new understandings and knowledge (Slavin, 1995; Brown & Campione, 1994; Rogoff, 1994). Students could not learn by only working in a small group. They needed to construct their knowledge. For this purpose, this study focused on construction of knowledge in small cooperative groups. Many students

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tend not to learn meaningfully, having difficulties relating what is taught to them with their real-world experiences, and with other scientific ideas previously learned (Novak, 2002). According to constructivism, the misconceptions students bring to science classes are remarkably resistant to instruction (Bodner, 1986). Therefore, in this study, lesson plans for teaching electrochemistry according to cooperative learning instruction were developed by considering students’ misconceptions. The treatment in the experimental group focused on using computer animations, brainstorming, experimental activities, examples from daily life, and illustrative figures to promote the acquisition of new conceptions and differentiation of the misconceptions. Students were encouraged to think, discuss and share, and the teacher provided feedback during the learning process. At the same time, students in the control group were treated by the teacher-centered traditional approach where students’ misconceptions were not taken into consideration. Following instruction, a post-test was administered to determine how the students were constructing understanding and making links between information studied in the lesson. The results showed that the constructivist approach-oriented instruction in cooperative groups caused a significantly better acquisition of scientific conception than for the traditional instruction. The mean score of students in the experimental group increased from 51.7% to 88.6%, a gain of 36.9%, and in the control group from 50.9% to 55.3%, a gain of 4.4%, after the treatment. The achievement increase of the students in the experimental group shows that the existing misconceptions were remedied and required learning goals were obtained on a large scale. Although the subject of electrochemistry was explained for the second time, teacher-centered instruction was not enough in remediation of students’ misconceptions. The reason for the increase of some students’ achievement in the posttest could be caused by repeating the subject of electrochemistry. From interviews with students, it was also concluded that the use of computer animations especially attracted students’ attention and helped them to understand and remember chemical concepts. The results were also in line with other research (Zeidler & McIntosh, 1989; Griffiths & Preston, 1992; Williamson & Abraham, 1995; Burke, Greenbowe & Windschitl, 1998). Students commonly worked in their groups and learned by enjoying themselves during the lessons. Group work also positively affected students’ learning. It was seen that students participated in group discussions, learned chemical concepts more easily, and helped other students. Other research on cooperative learning indicates the same results (Slavin, 1996; Jones & Steinbrink, 1989; Sharan & Sharan, 1990).


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It is very important to bring out the reasons for students’ misconceptions. Garnett et al. (1990a, 1990b), Garnett & Treagust (1992a, 1992b), and Sanger & Greenbowe (1997a, 1999) discussed some probable origins of students misconceptions in their research. These include: (i) compartmentalization of physical science subjects (e.g., treating chemistry and physics as distinct and independent subjects by using different terminologies to describe the same phenomena); (ii) inadequate prerequisite knowledge; (iii) misuse of everyday language in chemical situations; (iv) use of multiple definitions and models; (v) rote application of algorithms; and (vi) imprecise and inappropriate language used by textbooks in explaining electrochemical concepts. Based on our interviews with students, we established that misconceptions generally originated from textbooks and teachers. In addition, because Turkish students also learn electrolysis and about batteries in physics lessons, they hold some misconceptions such as those about the flow of protons, constitution of electrical current, etc. According to the analysis of some chemistry textbooks in Turkey, it can be said that there are some misleading statements and ineffective illustrations, and lack of construction of knowledge. Therefore, there is a need to revise textbooks based on constructivism and active learning methods. Arising out of the interviews and from our observations, we concluded that teachers_ lack of knowledge and motivation, and also learning methods cause misconceptions. Teachers generally are averse to learning and using contemporary learning methods and techniques in their lessons. Some teachers think that curriculum materials, supplies and equipment are lacking, thereby preventing the use of new methods. To cope with such problems concerning textbooks and teachers, studies continue to be conducted by the Ministry of National Education in Turkey. This study gives some evidence that if cooperative learning instruction is organized, giving consideration to constructivism, students’ achievement and also social skills will improve. The present research is also a comprehensive study for remediation of misconceptions. If the same studies can become reality and if teachers can be encouraged to apply them in their classes, then the formation of students’ misconceptions can be prevented. Thus, meaningful and effective learning can be provided for students. Consequently, when correct and suitable learning strategies are used, we believe that it is more likely that the sources of misconceptions and misunderstandings will be remedied. Therefore, it is very important to keep continually developing textbooks based on constructivism, including contemporary instructional methods.

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ACKNOWLEDGEMENT This study was supported by a grant from the University of Dokuz Eylul, Turkey (0.004.00.00.02). APPENDIX Some examples of items from the electrochemistry concept test 1. Answer the following questions according to the diagram below.

a) What kinds of reactions are taking place in each cell? b) What is happening at each electrode? c) How would you determine which electrode is the anode and which is the cathode? d) How is a current produced in this cell? How would you determine the direction of electron flow? e) Is the lamp alight or not? Why? f ) What do you think about the mass of each electrode? Is there any change in the mass of electrodes? Why? g) If there is no salt bridge will the lamp alight or not? h) What is the function of the salt bridge? i) What is the function of the voltmeter? j) If the salt bridge is replaced with the conductive wire do you think that there will be differences in the voltage? k) What does standard cell potential mean? l) What is a standard hydrogen electrode? Explain its importance?


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m) Explain the importance of using a platinum electrode in standard hydrogen electrode. n) What does E0cell mean? 2. As seen from the diagram above, a spoon is connected to the negative side of the battery and a silver plate is connected to the positive side. Answer the following questions according to the diagram. a) Determine the anode and cathode and their charges. b) What is the direction of electron flow in this electrolytic cell? c) What is the minimum value of the cell potential applied to the cell to drive the reaction in the desired direction? d) If the spoon and silver plate are replaced what will happen in this system?

3. Answer questions 3, 4 and 5 according to the diagram above. As seen in the diagram electrons are flowing from X to Y. According to the diagram mark the incorrect statement. A) B) C) D) E)

X is oxidized Y is reduced X is reductant H+ is oxidant The activity of X is higher than Y

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4. If the standard reduction potentials of X2+ and Y2+ are known, which item/items below could not be answered? I. Oxidation half reaction. II. Reduction half reaction III. Standard cell potential A) B) C) D) E)

Only I Only II Only III I and II I, II, III

5. Which statement/statements about electrochemical cells is/are wrong? I. Oxidation and reduction reactions occur independently in both of the beakers. II. Protons and electrons flow in the opposite directions to constitute an electric current. III. The attraction forces between anions and cations constitute cell potential. IV. Electric current is constituted by movement of electrons and anions. V. There are no changes in the mass of X and Y metals. VI. Electrons enter the electrolyte at the cathode, move through the electrolyte and emerge at the anode to complete the circuit. A) B) C) D) E)

I and VI II, III and VI V III All of them

6. Based on the cell notation for a spontaneous reaction: Ni (s) /Ni2+ (aq) //Cu2+ (aq) / Cu (s) A) B) C) D) E)

Ni2+ becomes reduced Ni is the anode Electrons flow in the external circuit toward the Ni electrode Cu2+ becomes reduced None of the above are correct


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Leman Tarhan Department of Chemistry Education, Faculty of Education, Dokuz Eylul University, Buca, Izmir, 35150, Turkey E-mail: [email protected] Burcin Acar Department of Chemistry Education, Faculty of Education, Dokuz Eylul University, Buca, Izmir, 35150, Turkey Tel: +90-232-4204882; Fax: +90-232-4204895.