Jurnal of chemical education

HALUK OZMEN, GOKHAN DEMIRCIO>LU and RICHARD K. COLL

A COMPARATIVE STUDY OF THE EFFECTS OF A CONCEPT MAPPING ENHANCED LABORATORY EXPERIENCE ON TURKISH HIGH SCHOOL STUDENTS_ UNDERSTANDING OF ACID-BASE CHEMISTRYReceived: 7 April 2006; Accepted: 28 June 2007

ABSTRACT. The research reported here consists of the introduction of an intervention based on a series of laboratory activities combined with concept mapping. The purpose of this intervention was to enhance student understanding of acid-base chemistry for tenth grade students_ from two classes in a Turkish high school. An additional aim was to enhance student attitude toward chemistry. In the research design, two cohorts of students were compared; those from the intervention group (N=31) and a second group (N=28) who were taught in a more traditional manner. Student understanding of acidbase chemistry was evaluated with a pretest/posttest research design using a purposedesigned instrument, the Concept Achievement Test (CAT) consisting of 25 items, 15 multiple choice and ten multiple choice with explanation. Alternative conceptions identified in the pretest were incorporated into the intervention, which thereby sought to move students toward views more in accord with scientific views for the concepts. Statistical tests indicate the instrument is reliable (with an alpha reliability of 0.81) and the analysis of the findings revealed statistically significant differences between the intervention and traditional groups with respect to conceptual understanding. Examination of student explanations and analyses of semi-structured interviews conducted with selected students suggest that the main influence was the laboratory activities. Analysis of the findings in the context of relevant literature that concept mapping in conjunction with laboratory activities is more enjoyable, helps student link concepts, and reduces their alternative conceptions. KEY WORDS: acids and bases, chemistry teaching, concept maps, laboratory activities

According to constructivist learning theory, students begin studying science, not as Fblank slates_, but bring to the classroom or laboratory a variety of ideas of, and experiences with, natural phenomenal that may influence their ability to understand different science concepts (Guba & Lincoln, 1989, 1994). Educational research suggests that students_ world views about scientific phenomena, as well as often being different to the science consensual views, may interfere with students_ learning of other scientific principles or concepts (Palmer, 1999). Such views are nowadays more commonly referred to as student alternative conceptions; a tacit recognition that these views and ideas are logical, sensible, and valuable from the students_ point of view, even if they differ from accepted scientific views (Ozmen, 2004; Pakua, Treagust & Waldrip, 2005). Research indicates that these beliefs are held by learners across differentInternational Journal of Science and Mathematics Education (2009) 7: 1Y24 # National Science Council, Taiwan (2007)

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grades or levels of education; that they are pervasive, stable, and resistant to change by conventional teaching strategies. CHEMISTRY TEACHINGAND

LEARNING

Chemistry is a key, enabling science, and is a subject that is considered by many to be difficult for secondary school students (see, e.g., Chang & Chiu, 2005; Lorenzo, 2005; Taber & Coll, 2002). A variety of reasons have been posited. Taber & Coll (2002) note that the chemistry concepts are abstract in nature and require students to construct mental images of things they cannot see, and thereby find it hard to relate to. A further complication in the learning of chemistry (and other sciences) noted in the literature concerns the medium of instruction. The literature on students_ problems with scientific language literacy, points to confusion between scientific terminology and similar sounding (or the same words in common language usage), suggesting this may result in students not understanding the meaning of scientific terms (Johnstone & Selepeng, 2001). Students for whom English is not their first language suffer more from such confusion if chemistry instruction occurs in English, probably due to lesser skills in English speaking, listening or reading of English (Coll, Ali, Bonato & Rohindra, 2006), or in some cases differences in world views as a result of cultural differences (Pakua et al., 2005; Sutherland & Dennick, 2002). IMPROVING CHEMISTRY TEACHING LEARNING

AND

Given the above, it is no great surprise that students find chemistry study challenging, and correspondingly teachers find some chemistry topics difficult to teach. The literature describes a variety of interventions or changes to pedagogy that researchers and teachers have used in an attempt to improve student learning in chemistry, and here we consider two, that the literature notes involves student being more active in their learning. One involves student learning in the laboratory; the second involves concept mapping. The literature suggest students enjoy laboratory work because it is more active, something they find more motivating (Hart, Mulhall, Berry, Loughran & Gunstone, 2000). In the laboratory, students have a chance to engage in hands-on activities, and both science and non-science majors are reported to find laboratory-based activities to be motivating and exciting (Markow & Lonning, 1998). There have been many studies reporting on the effectiveness of the laboratory instruction (e.g., Lazarowitz & Tamir, 1994; Hart et al., 2000; Demircio?lu, 2003), and despite some reservations (e.g., Nakhleh, Polles & Malina, 2002 report that laboratory work often lacks purpose or

A COMPARATIVE STUDY OF THE EFFECTS OF A CONCEPT MAPPING ENHANCED

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well-defined learning objectives) many authors believe that laboratory work helps promote conceptual change, particularly if the practical involves qualitative laboratory tasks. Another technique reported to enhance student conceptual understanding in science and chemistry is concept mapping (Novak & Gowin, 1984). Concept mapping is a form of two-dimensional diagramming which emphasizes the relationships among important concepts and helps students make conceptual connections while doing laboratory work (Markow & Lonning, 1998). Concept maps are constructed by writing concepts and linking them by labeled lines. The labels are important because they require whoever is constructing the map to actively select appropriate linking words. The links need to make sense, and to be genuine links between the two concepts; they need to relate the two concepts in some meaningful way (Novak & Gowin, 1984). The greater the number of valid links between concepts, the more sophisticated the map is considered to be (Novak & Gowin, 1984). Consistent with constructivist-based teaching, concept mapping involves students actively in constructing their own maps (Markow & Lonning, 1998). A substantial meta-analysis by Horton, Mcconney, Gallo, Woods, Senn & Hamelin (1993) concluded that concept mapping generally had positive effects on both student achievement and attitude, and concept mapping has been reported to provide a very effective strategy to help students learn meaningfully by helping them to see the links between scientific concepts (Adamczyk, Willison & Williams, 1994; Fisher, Wandersee & Moody, 2000). Concept mapping also has been reported to improve students_ problem-solving ability (Okebukola, 1992), and to aid collaborative learning, making it particularly appropriate in combination with laboratory learning environments, which often involve group work (Sizmur & Osbourne, 1997).

PURPOSE

OF THE INQUIRY

The research reported in this work builds upon the substantial research base into comparative or intervention-based studies (sometimes called quasiexperimental studies. The literature is replete with such studies; however, much of this research is based in so-called Western educational contexts and students for whom English is their first language. In contrast, as noted by Coll et al. (2006), rather less is known about effective pedagogies in nonWestern educational settings, and for the context of this study, Turkey (a new member of the European Union) there is a paucity of research. The chemistry topics used as the basis for this work involves concepts

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associated with acid-base chemistry. The authors propose that this is an appropriate choice given the ubiquitous nature of acid-base chemistry in everyday life (potentially providing access to student world views that might, or might not, conflict with scientific views), the fact that this area of chemistry involves multiple concepts (which Gabel, 1998 notes typifies chemistry learning difficulties), and the importance of acid-base chemistry for learning the topics in chemistry and related sciences such as biology, biochemistry. Additionally, acid-base chemistry is a topic for which there are reports that students find difficulty in learning (e.g., Bradley & Mosimege, 1998; Demircio?lu, Ozmen & Ayas, 2004; Nakhleh & Krajcik, 1994; Sisovic & Bojovic, 2000). In brief, the literature reports student alternative conceptions in acid-base chemistry as widespread, occurring at various grade levels and that conventional teaching strategies seem unable to rectify students_ nonscientific beliefs (Hewson & Hewson, 1984). Hence, here we report research about an intervention intended to help students learn acid-base chemistry more effectively. Given the complex nature of these topics, we decided to employ an intervention involving student activities in laboratory classes, supplemented by the use of concept mapping to help them see how to link concepts. In doing so, we recognize that it is difficult to attribute any positive outcomes in terms of learning to specifically to the influence of a laboratory-based activity or concept mapping for teaching acid-base chemistry. The approach, like all research approaches, also has limitations. We reflect on these issues in more detail in the discussion and conclusion to the paper. The purpose of this study is to investigate the effectiveness of an intervention for the teaching of acid-base chemistry in a Turkish secondary school. The specific research questions for this inquiry are: 1. Is an intervention involving the use of laboratory activities and combined supplemented by concept mapping more effective in improving students_ understanding of acid-base chemistry than traditional instruction in the context of a Turkish secondary school? 2. What, if any, alternative conceptions for acid-base chemistry are retained by students after the implementation of an intervention based on laboratory activities and concept mapping? METHODOLOGYAND

METHODS

This inquiry is interpretive in nature (Guba & Lincoln, 1994) and draws on constructivism. Learners are seen in this work as purposeful


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individuals who are active constructors of their own knowledge; this construction mediated by prior learning experiences and knowledge gained from previous instruction, and life experiences including peer and other interpersonal interactions. The inquiry is a comparative study that employed an intervention group, and a second group that was taught in a more traditional teacher-centered manner (called the traditional group). The subjects were 59 students (31 boys, 28 girls, average age 17 years) from two 10th grade classes. One class (n=31, 16 boys and 15 girls) was assigned as an intervention group and the other (n=28, 15 boys and 13 girls) as the traditional group. The students were similar in socioeconomic status with the majority of them coming from middle- to upper-class families. The school is a large co-educational school based in a city with a roll of about 800 students. There are about 45 teachers and 12 science teachers. Science is seen as an important subject for the school and is strongly supported by teachers, school administration and families. The school is generally well equipped and has four laboratories which have a variety of common chemistry laboratory equipment (glassware, balances, volumetric equipment, etc.). Normal instruction in the school is strongly teacher-dominated with a lecture type format typical, and students passively learning, writing notes and reading textbook material. Practical work is quite common, but is Fcookbook_ in style with students working their way sequentially through detailed, recipe-like, instructions and subsequently preparing reports and answering questions. The teacher who implemented the intervention, the usual teacher for acid-base chemistry for the tenth grade in the school, was a male with 14 years of teaching experience, who holds an MSc degree and a diploma in chemistry teacher education. Acid-base chemistry, and related topics like salts, is taught initially in the eighth year of Turkish elementary schools (age range 7Y14). However, in the second year of secondary school (i.e., tenth grade, age range 15Y17), these concepts are re-visited, and expanded upon. The unit Facids and bases_ is the last unit in general chemistry curriculum for the second grade of secondary school is presented in the tenth grade. This unit consists of: definitions of acid and base; properties of acids and bases; protolytic equilibrium in water; the pH concept; the strength of acids and bases; buffer solutions; and, hydrolysis of salts. Overview of the Procedures Used for the Intervention and Traditional Groups In this inquiry, the entire content of the acids and bases unit was taught using the same number of lessons, but applying different teaching

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approaches for the intervention and traditional groups. In each case, the same chemistry teacher was involved, in order to reduce to Fthe teacher effect_ . It is recognized that even using the same teacher does not necessarily avoid teacher bias (e.g., the teacher might be more interested in, and thus more enthusiastic about, the intervention); however, it was considered that using more than one teacher would further add to any variation and potentially confound the results. The teacher was given two 45-min training sessions prior to the intervention in order to make sure he understood the purpose of the laboratory activities, and the intended role of concept mapping for the intervention group. It also was important to ensure that the teacher understood the process of concept mapping as suggested by Buntting, Coll & Campbell (2006). In the case of the traditional group, the teacher was asked to teach the acid-base unit as he had done in the past. Lessons were presented five 45-min periods per week for a 4-week period and all lessons were subject to unobtrusive observation by the researchers. Teaching Approach Used for the Control Group The traditional instruction approach used in traditional group was based on the teacher providing explanations of the topics in a lecture type format, and using a textbook for worked examples and illustrations. The teacher did not seek to identify student alternative conceptions in advance (either from literature or for this cohort of students), and hence essentially ignored any students_ alternative conceptions during instruction. The teacher explained the concepts and then they were discussed in whole-class discussions, driven by teacher-directed questions. The majority of the lesson time (75Y85%) was based on instruction, and discussions arising from the teacher explanations and questions. The remaining time was devoted to completing worksheets developed based on the textbook and used as practice activities fro exams. While the students were studying the worksheets requiring written responses, the teacher walked around the classroom helping them as needed. During these activities, the students had the opportunity to ask questions. The worksheets were collected and subsequently analyzed by the teacher. Teaching Approach Used for the Intervention Group The intervention consisted of eight laboratory activities (i.e., two per week): Activity 1: Naming and identifying of acids and bases, Activity 2: Examining electric conductivity of some substances, Activity 3: Is there any difference between a strong acid or base and a concentrated


7

acid or base: Activity 4: Determining the strengths of given acids and bases, Activity 5: Testing a given sample whether or not it was an acid or a base, Activity 6: Determining acid-base properties of a given salt, Activity 7: Preparing a buffer, and Activity 8: Performing titrations (strong acid (HCl) with strong base (NaOH), strong acid (HCl) with weak base (NH3) and weak acid (HC2H3O) with strong base (NaOH)). These activities were prepared by the researchers based on information obtained from a review of literature about student learning difficulties in acid-base chemistry, and instructional material provided in a variety of chemistry textbooks. Thus the intervention sought to take into account student prior knowledge, consistent with a constructivist-based approach. The students in the intervention group were assigned to study groups (5Y6 per group) based on their achievement in a pretest on acid-base chemistry (see below). These groups were purposely designed to be similar, and heterogeneous in terms of student performance as based on the pre-test. A worksheet which included the goals for the practical activity, a list of equipment and substances, the practical procedure, and some probe questions was given to each group. The worksheets contained blank areas in which students were expected to write down their observations, provide explanations, prepare chemical equations, and draw conclusions (see Figure 1). The questions aimed to lead students to analyze experimental results, to compare the properties of different substances, to compare similarities and differences of chemical reactions, and to use previous knowledge in explanations and drawings). The use of the intervention was preceded by the administration of a pre-test (see below). This was deliberate to help the researchers (and teacher) become cognizant of student alternative conceptions for the topics covered in this unit. Before the activity began, the students were told about common alternative conceptions (i.e., as identified in the pretest and from the literature). However, these were not presented as being Fwrong_ , but as being ideas some students hold about the particular aspect of acid-base chemistry. The ideas were discussed with the students; this discussion aimed to potentially develop cognitive conflict in the students when they subsequently conducted the laboratory activity. The overall idea here was to help students see that they needed to consider competing explanations for their observations. After the discussion, the students carried out the activity in groups, during which the teacher explained the topics. For each laboratory activity, worksheets were distributed to the students and, as noted above, these included questions related to the concepts under instruction. At the end of the

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i) The aim of this activity is to examine electric conductivity of some substances. ii) The required equipment and substances for the activity; 1. Zinc and copper electrode 2. Power source and connection cables 3. Ampermeter 7. 0,1 M NaCl (aq) (Sodium chloride). 8. 0,1 M CH3COOH (aq) (Acetic acid) 9. 0,1 M NaOH (aq) (Sodium hydroxide) Substances HCl (aq) NaCl (aq) CH3COOH (aq) NaOH (aq) Vinegar juice Distilled water Ampoule Ampermeter

Lemon juice

4. Ampoule 5. Beaker (1000 ml) 6. 0,1 M HCl (aq) (Hydrochloric acid) Procedure: Set up in the following mechanism.

10. Vinegar juice 11. Distilled water 12. Lemon juice

1. Add 30 mL of hydrochloric acid solution to the beaker. And than switch the power source on. Observe the ampoule and the ampermeter for each change. Record your observations on the table above. A 2. Repeat Step 1 for each substance. 3. Answer the following questions: Discussion questions: 1. Which ones of given substances conduct electricity and why? ...................................................................................................... 2. Which substances conduct poor electricity? ...................................................................................................... 3. Why do the substances whose aqueous solutions conduct electricity show differences in this property? .............................................................................................

Figure 1. The worksheet for the Activity 3 used in this study.

activity the worksheets were evaluated by the teacher and given back to the students. This same procedure was repeated for all of the laboratory activities for the entire 4 weeks of the intervention. The overall intention was to draw upon the results of the pre-test and literature review of common student alternative conceptions for acid-base chemistry, and to engage in a laboratory activity that might remedy these alternative conceptions. An example of one such laboratory activity used with the


9

experimental groups is shown in Figure 1. The intention of this activity was to remedy the alternative conception that FAll acids and bases conduct electricity the same_ (Item 17 Table III). A second activity related to ways to test a sample; whether or not it was an acid or a base (Figure 2). This activity was based on previous research (Demircio?lu, Ayas & Demircio?lu, 2005) and aimed to remedy the alternative conception FThe only way to test a sample whether it is an acid or a base is to see if it eats something away, for example metal, plastic, animal, or us_ (Item 1, Table III). After each activity, group and whole-class discussions were conducted by the teacher. During discussions, alternative conceptions held by the students before the activity were re-evaluated; thus giving the students an opportunity to compare their previous and new knowledge. After these discussions, students were requested to prepare own concept maps to help their better understanding of the relationships between the concepts. Before engaging in the concept mapping activity, students were taught how to prepare concept maps (using the notions mentioned above, i.e., the need to provide meaningful links, etc.). For some of the practical activities the students filled an Fempty_ concept map, or drew a map about concepts they had studied before. The intention here was to help them become more familiar with the process of concept mapping as recommended in the literature (Buntting et al., 2006). It also is worthwhile to note here that concept mapping is more effective as an intervention when it is delivered as part of a longer term strategy,The purpose of the following activity is to remedy the student alternative conception that the only way to test a sample whether it is an acid or a base is to see if it eats something away, for example metal, plastic, animal, and us. Experimental tools and materials: test tubes, dropper, HCl solution, NaOH solution, litmus, methyl orange, phenolphthalein, lemon juice, vinegar, red cabbage, soapy water. Activity steps: In this test, you will be using three known indicators and red-cabbage juice. Follow the sequence in the chart given below. In each test, place about 4 cm3 of each solution in different test tubes. Then place 2-3 drops of the indicator into each of the test tubes. Carefully record the color in the test tubes. You are going to test the unknown solution after finishing the other tests. Solution 1. HCl solution 2. NaOH solution 3. Lemon juice 4. Vinegar 5. Soapy water 6. An unknown solution Litmus Phenolphthalein Methyl orange Red cabbage

Questions: 1. Which solutions used in the activity are acidic? Why? 2. Can you use red-cabbage juice to test a liquid whether it is an acid or a base? 3. What do you have to know about an indicator before its usage? Why?

Figure 2. The worksheet for the Activity 5.

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rather than a one-off activity (Buntting et al., 2006; Horton et al., 1993). Hence, during the teaching of the acid-base unit, the students prepared their own concept maps for acid-base theories, properties of acids and bases, the pH concept, the strength of acids and bases, neutralization, buffer solutions, and hydrolysis. EVALUATION INSTRUMENTS USEDIN THE INQUIRY

Student understanding of acid-base conceptions was evaluated by means of two instruments, and student interviews. These are now described in turn. The Concept Achievement Test (CAT) Instrument A 25-item achievement test for concepts covered in the acids and bases unit was constructed for the purpose of identifying the students_ understanding and alternative conceptions in chemistry. The test consists of 15 multiple-choice and ten multiple-choice questions which also sought explanations for the choices made in order to probe more deeply students_ understanding (see Dahsah & Coll, 2007). Each multiplechoice question included the scientifically acceptable answer; one common alternative conception reported in previous studies or identified during interviews (see below) or the pretest, and three plausible distracters. During the development of the CAT, first, instructional objectives related to the acids and bases topic were determined, based on the current chemistry curriculum (i.e., the acid-base chemistry unit). Second, literature related to students_ alternative conceptions about the acids and bases concepts was examined. Third, interviews were conducted with 15 students randomly selected from both groups (eight students from the traditional group and seven students from the intervention group) to investigate in depth their understanding and any alternative conceptions (see below). Following the interviews, a further review of research on students_ alternative conceptions about concepts identified in the interviews was conducted to validate the findings of interviews. Hence, overall the CAT consisted of questions developed by the researchers based on interview data and others questions from the literature (Bradley & Mosimege, 1998; Demircio?lu, 2003; Demircio?lu et al., 2005). The CAT was used in the pretest-posttest mode for the study to determine students_ conceptual understanding and the prevalence of their alternative conceptions. Content validation for the CAT was determined by a group of experts consisting of three chemistry educators in the researchers_ Department of


11

Secondary Science Education in the Faculty of Education and three high school chemistry teachers from the city of Trabzon who had taught chemistry for over 15 years. In addition, the CAT was piloted with 52 grade ten students, and the reliability assessed via item analysis. As the multiplechoice sections of the items in the CAT were dichotomously scored (0 for incorrect and 1 for correct) and conducted item analysis, Kuder-Richardson 20 formula for the reliability was used in this study. KR-20 is special case of Cronbach_ s alpha for dichotomous items. The reliability coefficient was found to 0.81, which was considered to be acceptable for an instrument of this type. Students took about 45 min to complete the CAT. Students Interviews As noted above the resign design included two groups, one involved in the intervention and a second that was taught in the normal, more traditional manner. Eight students from the traditional and seven from the intervention group were interviewed individually for 30 to 40 min before the implementation. These interviews sought to develop a more in-depth understanding of student understanding and any alternative conceptions. For both groups, the interviewees were a mixture of high achievers, middle or average achievers, and low achievers; based on grades they had received in previous school-based chemistry exams. A semi-structured approach was used in the interviews, all of which were audio taped and transcribed verbatim. The data from the interviews were used to develop the items of the Concept Achievement Test (CAT) as mentioned above. RESEARCH FINDINGS As noted above, in this inquiry, a non-equivalent pretest-posttest research design was used, for both intervention and traditional groups. Prior to the intervention (i.e., the concept mapping and laboratory-based activities), the CAT was administered to students for both the intervention and control groups. Means and standard deviations of the scores for both groups obtained from the CAT and are given in Table I. Independent samples t-test show no statistically significant differences between the intervention and traditional groups (M = 33.13, SD = 17.51, M = 35.03, SD = 18.69, respectively) with respect to chemistry achievement (t = 0.404, df = 57, p 9 0.05), indicating that students in the experimental and traditional groups were similar. Because there were no statistically significant differences see for pretest scores for the two groups, posttests scores of the groups were compared using the

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independent t-test. Comparison of the two groups for the CAT is given in Table II. These data reveal statistically significant differences in chemistry achievement between the intervention and traditional groups (M = 57.36, SD = 15.12, M = 78.39, SD = 14.56; t = 5.581, p G 0.001) (Table II). This suggests that the achievement of students from the intervention group in the test was higher statistically significantly than students in the traditionally taught group. The second research question concerned student alternative conceptions of acid-base chemistry before and after instruction (intervention or traditional teaching). As noted above, in the intervention group, during the intervention, experimental activities were used in an attempt to remedy students_ alternative conceptions identified in the pretest. Examination of the posttest results suggests that the intervention group had fewer alternative conceptions after instruction (by a ratio of about three to one) than the traditionally taught group (Table III). Data in Table III reveal that six alternative conceptions identified for the intervention group in the pretest were changed to become in agreement with the scientific conception post-intervention: (i) In all neutralization reactions, acid and base consume each other completely; (ii) Electrolysis and hydrolysis are the same (iii); All acids and bases are harmful and poisonous; (iv) The only way to test a sample whether it is an acid or a base is to see if it eats something away, for example, metal, plastic, animal, and us; (v) pH is only a measure of acidity; and, (vi) Salts don_t have a value of pH. However, in the case of the traditionally taught group, all of these alternative conceptions, except FpH is only a measure of acidity_, were retained. Details of these findings are now presented. Student alternative conceptions about neutralization concepts determined in the study pretest were: FIn all neutralization reactions, acid and base consume each other completely_, FAt the end of all neutralization reactions, there is neither H+ nor OHj ions in the resulting solutions_, and FAfter all the neutralization reactions, the pH of formed solution is always 7_. The first alternative conception (Item 13, Table III) was held by 48% of the intervention group students pretest, but none posttest. InTABLE I Means and standard deviations for the results of the CAT prior to treatment Groups Measures CAT Intervention group N 31 Mean 33.13 SD 17.51 Traditional group N 28 Mean 35.03 SD 18.69 t 0.404 p 0.815


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TABLE II Comparison of the intervention and traditional groups for overall differences in CAT after the treatment Groups Measures CAT Intervention group N 31 Mean 78.93 SD 14.56 Traditional group N 28 Mean 57.36 SD 15.12 t 5.581 p 0.000

contrast, for those taught traditionally, 54% held the alternative conception pretest and 36% posttest. The second alternative conception (Item 14, Table III) for the intervention group students post-intervention, showed a decrease from 65 to 16% pretest posttest, whereas for the traditionally taught group, this changed from 61 to 32%. The third alternative conception (Item 16, Table III) was held by 45% of the intervention group pretest and 10% posttest; and for the other group 54% pretest and 21% posttest. Alternative conceptions about salts determined in the study were: FAll salts are neutral_, and FSalts don_t have a value of pH_. The former (Item 3, Table III) was held by 61% of the intervention group pretest and 19% posttest, and 64% pretest and 39% posttest for those traditionally taught. The other alternative conception (Item 4, Table III) was held by 25% of the traditionally taught group posttest, but none of the intervention group posttest. Two alternative conceptions: FAs the value of pH increase, acidity increase_ (Item 8, Table III), and FpH is only a measure of acidity_ (Item 9, Table III) were common alternative conceptions related to the pH concept held by the students. Some 32% of the intervention group and 29% of the others held the first alternative conception pretest, and 6 and 7%, respectively, posttest. Likewise for the second alternative conception about pH, 39% of the intervention group students and 29% of the control group held this pretest, and none posttest. One alternative conception revealed in the inquiry was related to testing an acid: FThe only way to test a sample whether it is an acid or a base is to see if it eats something away, for example metal, plastic, animal, and us_ (item 1, Table III). Some 39% of the intervention group held this pretest and none posttest; but for the other group 43% held it pretest, and 18% posttest. Acids burn and melt everything (Item 2, Table III)

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TABLE III Intervention group Pretest f 12 16 19 10 13 15 8 10 12 9 13 8 15 20 11 14 10 48 65 35 45 32 0 5 4 3 1 52 61 32 42 48 26 32 39 29 42 26 2 6 0 0 5 4 2 0 4 0 1 39 0 0 6 19 0 0 16 13 6 0 13 0 3 0 16 13 10 3 % f % f 12 13 18 11 10 14 6 8 8 7 14 9 15 17 8 15 9 Posttest Pretest % 43 46 64 39 36 50 21 29 29 25 50 32 54 61 29 54 32 Traditional group Posttest f 5 6 11 7 3 9 3 2 0 6 4 3 10 9 3 6 5 % 18

Students_ alternative conceptions determined in pre-test and post-test

Student alternative conceptions

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2 3 4 5 6 7 8 9 10 11 12

21 39 25 11 32 11 7 0 21 14 11 36 32 11 21 18

13 14

15 16 17

The only way to test a sample whether it is an acid or a base is to see if it eats something away, for example metal, plastic, animal, and us Acids burn and melt everything All salts are neutral Salts don_t have a value of pH All acids and bases are harmful and poisonous Strong acids can react with all metals to form H2 gas Strength of an acid depends on the number of hydrogen atoms in an acid As the value of pH increases, acidity increases pH is only a measure of acidity A strong acid is always a concentrated acid Electrolysis and hydrolysis are the same A strong acid doesn_t dissociate in water solution, because its intra-molecular bonds are very strong In all neutralization reactions, acid and base consume each other completely At the end of all neutralization reactions, there is neither H+ nor OHj ions in the resulting solutions As concentration of H3O+ ions in an acid solution increases, pH of the solution increases After all the neutralization reactions, the pH of formed solution is always 7 All acids and bases conduct electricity the same


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and FAll acids and bases are harmful and poisonous_ (item 5, Table III) were common alternative conceptions related to the effects of acids and bases on matter revealed in the inquiry. The former was held by 52% of the intervention group 46% of the control group pretest, and 6, and 22%, respectively, posttest. The second alternative conception was held by 42% and 36% for the intervention and other group pretest, and 0 and 11%, respectively, posttest. There were ten items for which students were required to present an explanation for their selection. These proved useful probes and in order to see the changes in understanding for both groups some detail is now provided for Item 22. Item 22 presented here was developed to investigate students_ understanding of FThe effect of acids on metals and carbonates_ . The scientifically accepted response for this item is option C (identified with an asterisk *). The students were asked to decide the gas or gases that are produced a result of the reactions inside the plate I and II and were requested to write an explanation. Acceptable explanations are: FSince copper is a inert metal, it is not possible for it to have reaction with hydrochloric acid, on the other hand, as a result of reaction between calcium carbonate and hydrochloric acid, carbon dioxide is formed according to the equation: CaCO3 +2HCI Y CaCI2 + CO2 + H2O. As a consequence, only the gas CO2 is collected in plate III_.

Posttest, 75% of the intervention group and 45% of the other group chose the correct option, and 70 and 32%, respectively, gave scientifically acceptable explanations. For this item, 16 and 32% of the intervention and other group chose option D, and examination of their explanations suggested they thought that strong acids can react with all metals to form H2 gas (Item 6, Table III).

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In summary, both of the groups showed progress in changing their alternative conceptions to conceptions more in agreement with the scientifically acceptable views, but the intervention group performed better overall. It is worthwhile to note here, that although the intervention group performed better, this does not mean all alternative conceptions were corrected; the reasons for this are discussed in detail below. DISCUSSION Student Understanding of Acid-base Chemistry and Practical Laboratory Activities Literature reports on research of student understanding of acid-base chemistry suggest that students at a variety of teaching levels hold alternative conceptions about many concepts (Bradley & Mosimege, 1998). The literature also points to a need for pedagogies that will help avoid, or change, these alternative conceptions and thus improve students_ conceptual understanding (Nakhleh & Krajcik, 1994; Sisovic & Bojovic, 2000; Demircio?lu, 2003; Demircio?lu et al., 2005). This notion forms the basis for the present inquiry. Examination of the pretest and posttest data for the two groups involved in this work reveal statistically significant differences in conceptual understanding as determined via the CAT instrument (Table II). These differences appear to arise from the use of the intervention; namely, the laboratory activities and concept mapping. With our research design, it is probably impossible to identify explicitly which component, or whether it is the combination, that brings about the change. One could argue that is does not especially matter which part of the intervention brings about conceptual change. However, if one part of the intervention alone brings about conceptual change, it would mean the other component is unnecessary, meaning, a simpler intervention may be equally effective. Such problems are not uncommon in intervention studies, which seldom involve all necessary elements of Ftrue_ scientific testing (e.g., double-blind intervention, genuine random sampling etc, see Rennie, 1998). Below now attempt to discern which aspects of the intervention are of importance in effecting conceptual understanding? We do this by looking for links between the activities and the particular alternative conception under investigation. First, we ague that direct encounter with chemicals in the laboratory is an important influence in student understanding. Consider some examples, which we believe illustrate this proposition. Analysis of the


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data from the first test item in the CAT instrument suggests that the students held the alternative conception that FStrong acids can melt metals and destroy them_; they drew the conclusion that the interaction was not a transforming process and that the metal was Fdisappearing_. It is argued here that this alternative conception was addressed by applying enriched activities to the intervention group. The chosen acids - H2SO4, HNO3 and HCI - were investigated in the laboratory to give students the opportunity to actually experience the interaction of metals and acids (an alternative conception identified in the literature; see, Demircio?lu et al., 2004; Nakhleh & Krajcik, 1994). From physical observations in the laboratory the students were able to see clearly that a chemical reaction was occurring in front of them only with some different metals; and as a result they could see that melting of metals did not occur, and that not all metals reacted with acids. Hence, for this we argue that the laboratory exercise is likely the most influential component. A second illustration concerns a student alternative conception that FThe only way to test a sample whether it is an acid or a base is to see if it eats something away, for example metal, plastic, animal, and us_. The laboratory exercise that accompanied the teaching of this concept involved showing students the testing of acids and bases using litmus paper or other indicators. Again here a visually dramatic practical demonstration was encountered by students; this observation being in stark contrast to their prior conceptions (and those of the traditionally taught group). This result contrasts with work by Demircio?lu et al., (2005), in which the same alternative conceptions were found, but not so readily overcome. Similar things were seen for the alternative conception that FAll acids and bases have similar electrical conduction_. Using the experimental apparatus in Figure 1 the students measured the conductivity of different acid and base solutions. By doing the experiment themselves, the students could observe directly differences in electrical conductivity values for different concentrations of acid and base solutions and weak and strong acids and bases. A similar thing occurred with the alternative conception that FAll the metals have a reaction with a result of releasing gases with acids_. This alternative conception probably arose because of student prior experiences with reactive metals and acids such as the reaction between hydrochloric acid and magnesium-zinc metals, leading them to think all acids have similar reactions. However, the fact that they could not see any observable, physical reaction between with acids and the inert metal copper helped correct this alternative conception. Again here we would argue that the laboratory exercise is likely the most influential component.

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The ability to understand aspects of acid-base chemistry even at the molecular/particulate level also was evident here; as a result of the laboratory activities. For example, both groups of students said that they could observe phenomena in which acids and bases release H+ or OHj ions in aqueous solution, and thus decide whether materials are acidic or basic in nature. Support for this notion came from an interview in which one student commented: F... first we look after what kind of gases they spread out, if it is H+ so the material is acidic, otherwise if it is OHj, the material is basic ... after we prepare the aqueous solution, if it spreads H+, it is acidic ... we add water into the solution, if the salt happens, it is acidic_ . According to the literature (e.g., Demircio?lu et al., 2004, Demircio?lu et al., 2005), such alternative conceptions occur as a result of students not being involved in laboratory activities or experiments, but just listening to what their teachers tell them. If these and similar concepts are investigated in actual experiments in the laboratory, it seems likely students could better understand which events are observable and which of them are not (and occur at the atomic or molecular level). Again here we would argue that the laboratory exercise is likely the most influential component. Further support for the proposal here about the importance of practical laboratory work is provided in the literature (see, e.g., Botton, 1995; Sisovic & Bojovic, 2000), and it seems that the fact that most laboratory work (including that in this inquiry) involves students working in groups helps provide students with advantages compared with traditional instruction. The reason for this may be that in groups, as was observed in this work, students have to agree on observations and defend the accuracy of such observations and any subsequent explanations (see Nakhleh, Polles & Malina, 2002). In support of this Sisovic & Bojovic, (2000) also used laboratory-based activities involving group work for electrical conduction of acid and bases. In this case, within-group augmentation was supported by whole-class discussion. This may be a useful way of addressing what Schmidt (1991) refers to as a Fhidden persuader_ . Consider Item 8; pretest data suggested the students held alternative conceptions about neutralization: FAfter all the neutralization reactions, the pH of formed solutions is always 7_, and FWith the result of the neutralization of strong acid and strong base, neither H+ nor OHj ions was there in the resulting solution_. The first alternative conception is probably a result of the idea that FSalt occurs in neutralization reactions and all the salts are neutral, and the second alternative from different usage of the term of, Fneutral_ which also occurs commonly in daily life (see, Ayas & Demircio?lu, 2002; Demircio?lu et al., 2001).


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Schmidt (1991) says a Fhidden persuader_ like this can come from students being: introduced to a specific example of neutralization (strong acids reacting with strong bases to give a neutral solution) and applying this to other examples to which it does not actually apply. In the present work, students did activities which involved the reaction of hydrochloric acid with ammonia and measuring the pH of the resulting salt solution, which was plainly not neutral. Student Understanding of Acid-base Chemistry and Concept Mapping A further feature of the intervention employed in this work involved students constructing their own concept maps about acid-base chemistry concepts. These then formed part of whole-class discussions done after the students had completed the laboratory activities. The findings here suggest the development of concept maps did three things. First, it formed a key part of the laboratory acuities in that it was part of student argumentation and defense of their ideas. This was evidenced during observations of the students_ laboratory activities. Second, it helped students to better understand the result of their practical laboratory activities. Third, examination of students_ concept maps also allowed the teacher to identify alternative conceptions or gaps in student learning during the intervention. Hence, it formed an integral part of the intervention because the maps helped the teacher understand student thinking. Examples of some student concept maps are shown below (Figure 3). In this work we used concept maps in conjunction with laboratory activities. This type of approach is supported by the literature, which recommends teachers do not rely on one teaching approach, but use a variety of teaching methods and, perhaps most importantly, do more hands-on activities in their classrooms (Khalili, 2001). However, the literature provides something of a Fmixed-bag_ in terms of support for the use of practical work alone in enhancing student understanding. Although most authors consider laboratory activities to be an important part of chemistry education (e.g., Hart et al., 2000; Lazarowitz & Tamir, 1994), there is conflicting evidence as to whether or not laboratory activities alone increase student understanding of chemistry. Some researchers, for example, believe laboratory work cognitively overloads students, meaning they have too many things to recall (Johnstone & Wham, 1982). If, as some have argued, laboratory activities on their own are not sufficient to increase student_s understanding, it may be that in the present work the use of a combination of activities helps. In support

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Figure 3. Examples of some student concept maps.

of this proposition, concept maps accompanied by laboratory activities have been reported elsewhere as playing an important role in student success (Markow & Lonning, 1998). Could the use of concept maps alone result in improved understanding? Again the literature is mixed. Some studies suggest the use of concept maps helps students understand the relationships between concepts and helps make them achieve meaningful learning (Horton et al., 1993), others suggest the gains may be small or temporary (see, Freedman, 1997; Hart et al., 2000; Markow & Lonning, 1998). Buntting et al., (2006) say concept mapping is of limited value if used in a one-off type scenario, but is more effective if used for longer (e.g., a term or significant part of a term). There is limited literature on the combined use of concept maps with laboratory activities. Work by Markow & Lonning (1998) suggests that constructing pre-lab and post-lab concept maps helps students understand the concepts involved in the laboratory experiment before they performed them. The post-lab concept maps were apparently good indicators as to how students were able to relate the new concepts to their pre-conceptions. Additionally, Novak & Gowin (1984) report that after a learning task has been completed, concept maps provide a schematic summary of what has been learned. This is essentially how concept mapping was used in this work; the concept maps were used during and after the laboratory applications and were found to be useful in tracking student understanding. Hence, overall, based on analysis of the data from of our work here, it seems laboratory


21

work is the most important component of this intervention. However, the literature points to at least some influence, along with added benefits, to the use of concept mapping in conjunction with laboratory work. The paucity of research in combined pedagogies like done in this work suggests this could be a fruitful area for more research; perhaps with several cohorts of students involved in a variety of interventions; some using laboratory activities, some concept mapping and some a combination of the two.

CONCLUSIONS

AND IMPLICATIONS

This inquiry sought to determine the effectiveness of an intervention comprising a combination of laboratory activities supported by concept mapping on students_ understanding of acid-base chemistry concepts, and in remedying alternative conceptions for these topics. The research findings for the inquiry suggest the intervention can enhance student understanding for acid-base chemistry, and seems the visually dramatic and hands-on nature of the practical work is particularly helpful. The literature suggests that many high school students experience a traditional teacher-centered approach to learning chemistry where they sit rather passively, listening to the teacher without asking many questions, and perhaps participate only to the extent of raising their hand to answer or ask questions (Muir-Hertzig, 2004). Such an approach is thought to reward rote memorization of concepts without developing conceptual understanding. Current theories of learning such as constructivism and meaningful learning theory suggests that learning consists of interaction between students_ preexisting knowledge and new knowledge that the learning process should be more active in nature. In other words, student-centered learning pedagogies may, as suggested here in our work, be useful ways of enhancing meaningful learning. Of course, laboratory activities and concept mapping used in this study are only two active teaching approaches open to teachers. Despite the largely quantitative nature of our work, it is not appropriate to attempt to generalize our work to a wider context (Guba & Lincoln, 1994). From this perspective, given a reasonably detailed description of our work, the reader is best positioned to judge the relevance of our work to his or her own educational setting. With this thought in mind, we make some proposals as to what we think our work might mean for others. The results of this inquiry suggests that laboratory-based applications have positive effects on students_ under-

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standing, consistent with at least some literature (Botton, 1995; Gouveia & Valadares, 2004). Of course one need not use this particular combination of pedagogies, but Stensvold & Wilson (1992) recommend teachers use combinations of teaching approaches to improve understanding of the procedures used in the laboratory. This, they argue, helps student link results to appropriate prior knowledge of science concepts, and improves the integration of laboratory content within an individual_s conceptual structure. For this reason, we think concept mapping would likely be one of those methods. In conclusion, our work suggest combining the pedagogies of laboratory-based activities and concept mapping may be a useful strategy for teaching acid-base chemistry concepts, and teachers may also wish to consider this approach or another combination when teaching chemistry concepts.

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Demircio?lu G., Ozmen H., Ayas A. (2004) Some concept alternative conceptions encountered in chemistry: A research on acid and base. Educ Sci: Theory Prac, 4:73Y80. Demircio?lu G., Ayas A., Demircio?lu H. (2005) Conceptual change achieved through a new teaching program on acids and bases. Chem Educ Res Prac, 6:36Y51. Fisher K.M., Wandersee J.H., Moody D.E. (2000) Mapping biology knowledge. Kluwer, Dordrecht. Freedman M.P. (1997) Relationship among laboratory instruction, attitude toward science, and achievement in science knowledge. J Res Sci Teach, 34:343Y357. Gabel D. (1998) The complexity of chemistry and implications for teaching. In: Fraser B.J., Tobin K.G. (Eds) International handbook of science education (pp 233Y248). Kluwer, Dordrecht. Gouveia V., Valadares J. (2004) Concept maps and the didactic role of assessment. Concept maps: theory, methodology, technology. In: Canas A.J., Novak J.D., Gonzalez F.M. (eds) Proc First Int Conf on Concept Mapping. Pamplona, Spain/September 14Y17, 2004 http://cmc.ihmc.us/CMC2004Programa.html. Guba E.G., Lincoln Y.S. (1989) Fourth generation evaluation. Sage, Newbury Park, CA. Guba E.G., Lincoln Y.S. (1994) Competing paradigms in qualitative research. In: Denzin NK, Lincoln YS (eds) Handbook of qualitative research (pp 105Y117). Sage, Thousand Oaks, CA. Hart C., Mulhall P., Berry A., Loughran J., Gunstone R. (2000) What is this purpose of this experiment? Or can students learn something from doing experiments? J Res Sci Teach, 37:655Y675. Hewson P.W., Hewson M.G. (1984) The role of conceptual conflict in conceptual change and the design of science instruction. Instruct Sci, 13:1Y13. Horton P.B., McConney A.A., Gallo M., Woods A.L., Senn G.J., Hamelin D. (1993) An investigation of the effectiveness of concept mapping as an instructional tool. Sci Educ, 77:95Y111. Johnstone A.H., Wham A.J.B. (1982) The demands of practical work. Educ Chem, 19(3):71Y73. Johnstone A.H., Selepeng D. (2001) A language problem revisited. Chem Educ: Res Prac Eur, 2(1):19Y29. Khalili F. (2001) Chemistry laboratory innovations using universal lab interface (ULI). Paper presented at the 31st ASEE/IEEE Frontiers in Education Conference. Reno, NV, October. Lazarowitz R., Tamir P. (1994) Research on using laboratory instruction in science. In: Gabel D. (ed) Handbook of research on science teaching and learning (pp 94Y128). MacMillan, New York. Lorenzo M. (2005) The development, implementation and evaluation of a problem solving heuristic. Int J Sci Math Educ, 3(1):33Y58. Markow P.G., Lonning R.A. (1998) Usefulness of concept maps in college chemistry laboratories: students_ perceptions and effects on achievement. J Res Sci Teach, 35:1015Y1029. Muir-Hertzig R.G. (2004) Technology and its impact in the classroom. Compute Educ, 42:111Y131. Nakhleh M.B., Krajcik J.S. (1994) Influence of levels of information as presented by different technologies on students_ understanding of acid, base, and pH concepts. J Res Sci Teach, 34:1077Y1096.

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Nakhleh M.B., Polles J., Malina E. (2002) Learning chemistry in a laboratory environment. In: Gilbert J.K., De Jong O., Justi R., Treagust D.F., Van Driel J.H. (eds) Chemical education: towards research-based practice (pp 69Y94). Kluwer, Dordrecht. Novak J.D., Gowin D.B. (1984) Learning how to learn. Cambridge University Press, Cambridge. Okebukola P.A. (1992) Can good concept mappers be good problem solvers in science? Educ Psychol, 12(2):113Y129. Ozmen H. (2004) Some student alternative conceptions in chemistry: a literature review of chemical bonding. J Sci Educ Tech, 13:147Y159. Pakua S., Treagust D.F., Waldrip B. (2005) Village elders_ and secondary school students_ explanations of natural phenomena in Papua New Guinea. Int J Sci Math Educ, 3(2):213Y238. Palmer D. (1999) Exploring the link between students_ scientific and nonscientific conceptions. Sci Educ, 83:639Y653. Rennie L.J. (1998) Improving the interpretation and reporting of quantitative research. J Res Sci Teach, 35(3):237Y248. Schmidt H.J. (1991) A label as a hidden persuader: chemists_ neutralization concept. Int J Sci Educ, 13:459Y471 Sisovic D., Bojovic S. (2000) Approaching the concepts of acids and bases by cooperative learning. Chem Educ: Res Prac Eur, 1:263Y275. Sizmur S., Osbourne J. (1997) Learning processes and collaborative concept mapping. Int J Sci Educ, 19(10):1117Y1135. Stensvold M., Wilson J.T. (1992) Using concept maps as a tool to apply chemistry concepts to laboratory activities. J Chem Educ, 69(3) 230Y232. Sutherland D., Dennick R. (2002) Exploring culture, language and the perception of the nature of science. Int J Sci Educ, 24(l):lY25. Taber K.S., Coll R.K. (2002) Bonding. In: Gilbert J.K., De Jong O., Justi R., Treagust D.F., Van Driel J.H. (eds) Chemical education: towards research-based practice (pp 213Y234). Kluwer, Dordrecht Haluk Ozmen Department of Science Education, Karadeniz Technical University Fatih Faculty of Education, Trabzon, 61335, Turkey E-mail: [email protected] Gokhan DemNrcNo?lu Department of Secondary Science and Mathematics Education, Karadeniz Technical University Fatih Faculty of Education, Trabzon, 61335, Turkey E-mail: [email protected] Richard K. Coll Centre for Science and Technology Education Research, University of Waikato, Hamilton, New Zealand E-mail: [email protected]

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