laponite nanoparticles immobilized on glassy carbon electrode: Direct electron transfer and multielectrocatalysis

MUAMMER ÇALIK, ALIPAŞA AYAS and RICHARD K. COLL

INVESTIGATING THE EFFECTIVENESS OF AN ANALOGY ACTIVITY IN IMPROVING STUDENTS’ CONCEPTUAL CHANGE FOR SOLUTION CHEMISTRY CONCEPTS Received: 23 March 2007; Accepted: 17 April 2008

ABSTRACT. This paper reports on an investigation on the use of an analogy activity and seeks to provide evidence of whether the activity enables students to change alternative conceptions towards views more in accord with scientific views for aspects of solution chemistry. We were also interested in how robust any change was and whether these changes in conceptual thinking became embedded in the students’ long-term memory. The study has its theoretical basis in an interpretive paradigm, and used multiple methods to probe the issues in depth. Data collection consisted of two concept test items, one-on-one interviews, and student self-assessment. The sample consisted of 44 Grade 9 students selected from two intact classes (22 each), from Trabzon, Turkey. The interviews were conducted with six students selected because of evidence as to their significant conceptual change in solution chemistry. The research findings revealed statistically significant differences in pre-test and post-test scores, and pre-test and delayed post-test scores (p G 0.05), but no differences between post-test and delayed test scores (p 9 0.05). This suggests that the analogy activity is helpful in enhancing students’ conceptual understanding of solution chemistry, and that these changes may be stored in the students’ long-term memory. KEY WORDS: analogy, chemistry education, conceptual change, conceptual understanding, types of solutions

INTRODUCTION School science curricula are replete with concepts that teachers report students find difficult to understand. There have been many reports in the literature of ways in which teachers might bring about conceptual change, however, a constant problem is that many proposed teaching approaches require more classroom time, and at the same time teachers also complain of a ‘crowded curriculum’ (Çalık, Ayas & Ebenezer, 2005; Çalık & Ayas, 2005b; Çalık, Ayas & Coll, 2007). Teachers then typically have a busy schedule, and even if they wish to find new ways of teaching problematic science concepts, they may lack the time or opportunity to find and read about new trends and innovations in science education. Even if they manage to find new teaching activities they wish to try out, they have limited time to implement new material, activities, or teaching strategies. There is some research that seeks to address the issue of helping teachers International Journal of Science and Mathematics Education (2009) 7: 651Y676 # National Science Council, Taiwan 2008

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teach difficult science topics even in the face of a crowded curriculum. We are not talking here about ‘tips for teachers’, but rather interventions developed from sound research and based on an understanding of how students learn. In other words, these are interventions with a solid theoretical base. One example of this is provided by Çalık & Ayas (2005a), who devised an activity related to solution chemistry–specifically about unsaturated, saturated, supersaturated, dilute and concentrated solutions. This work was based on constructivism, and a theoretical assumption in the work was that learners actively construct and transform their own meanings, rather than passively acquire and accumulate knowledge transmitted to them. The work by Çalık & Ayas (2005a) drew upon earlier work by Çalık (2005) and Pınarbaşı & Canpolat (2003) that identified students’ alternative conceptions about solution chemistry. Çalık & Ayas (2005a) then developed an analogy activity to address students’ alternative conceptions of solution chemistry. This was generally successful; however, some limitations in implementing the activity were noted at the time. The present work seeks to build upon this earlier work on the applicability of an analogy activity and seeks to provide sound evidence as to whether such activities enable students to change their alternative conceptions towards scientific conceptions and whether any changes observed are robust. First we discuss the literature on teaching with analogies and show how we have drawn upon this literature to devise the teaching approaches in the present work. Analogies One of the central tenets of constructivism, and its variants (see Good, Wandersee & St Julien, 1993), is that when learners construct new knowledge (e.g., when in the classroom), this is mediated by what they already know. Wheatley (1991) suggests that the learner compares the ‘new knowledge’ (i.e., the material being taught) with what he or she already knows. Hence, a key feature of constructivist notion points to the importance of learners’ prior knowledge when developing teaching activities or approaches. That is, the learner tries to relate new knowledge with what he or she already knows; this forms the basis of analogies. Coll, France & Taylor (2005) suggest that analogies work for this very reason, and that the learner here is acting much the same way as a scientist does. Duit (1991) describes this as a process of mapping of shared attributes. So, for example, we model the structure of the atom by comparing it with the solar system, and map attributes from the analog domain (the solar system) to the target, that is what we want to learn or understand (i.e., the structure

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of the atom). So here the nucleus is like the sun, the electrons like the planets, the electron orbit like the planetary orbit, and so on. Usage of analogy is ubiquitous in the classroom (Brown, 1993; Brown & Clement, 1989; Dagher, 1995a), and one reason they are preferred is that they avoid students feeling their own ideas are undervalued (Chiu & Lin, 2002; Taylor & Coll, 1997). This is thought to occur since the use of analogy directly (i.e., as a teaching tool, rather than as an approach to correct misconceptions) avoids direct cognitive conflict (Clement, 1983; Glynn, 1989; Glynn, Britton, Semrud-Clikeman & Muth, 1989). Interestingly, despite their inherent appeal, analogies are reported to be something of a ‘double-edged sword’ (Harrison & Coll, 2007; Harrison & Treagust, 2006). Teaching with Analogies There is now a substantial body of literature reporting on the benefits of teaching with analogies, and many reports of their success (see, e.g., Coll, France, & Taylor, 2005; Dagher 1995b). Recent research has focused on devising teaching models to use ‘teaching with analogies’. Several have been proposed. Glynn (1991) developed the Teaching with Analogies (TWA) model and Harrison and colleagues the Focus Action Reflection (FAR) model (Harrison & Treagust, 2006; Treagust, Harrison, & Venville, 1998). Other authors have suggested that teaching using multiple analogies is better than teaching using a single analogy (see, e.g., Chiu & Lin, 2002). Overall, the literature suggests that key features of teaching with analogies are to (a) ensure the analogy is familiar to the students (Coll et al., 2005), (b) map as many shared attributes as possible (Treagust, Harrison, & Venville, 1998), and (c) identify where the analogy breaks down (Harrison & Treagust, 2006). Research Aim and Research Questions The overall aim of this work was to investigate the use of an analogy activity in the teaching of some aspects of solution chemistry. We wanted to see if the use of analogy helped students’ conceptual understanding of solution chemistry in the way the above literature suggests. Specifically, the present work sought to: 1. Devise an analogy activity for use in teaching solution chemistry. 2. Evaluate some Turkish grade 9 students’ conceptual understanding of solution chemistry before and after exposure to an analogical teaching activity.

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3. Evaluate if any changes to Turkish grade 9 students’ conceptual understanding of solution chemistry are retained. THEORETICAL BASIS

TO THE

STUDY

The research reported here was conducted within an interpretive paradigm (Guba & Lincoln, 1989, 1994; Lincoln & Guba, 1985) and drew upon constructivism as a theory of learning (Wheatley, 1991). The authors thus believe that students construct their own mental images of scientific concepts during teaching, and that this construction is mediated by their own pre-existing knowledge, much of which has its origins in prior learning experiences (Good et al., 1993). The analogy activities developed for this work took such thinking into account and the researchers drew upon their extensive knowledge of the Turkish educational system, and their own learners – including those that participated in this study (this latter from previous research, see Çalık & Ayas, 2005a; Çalık, Ayas & Coll, 2007; Çalık, Ayas & Ebenezer, 2005). METHODS Sample The sample consisted of 44 grade 9 students (18 boys and 26 girls) selected from two different classes (22 each) in the city of Trabzon, Turkey. Some students were scholarship students funded by the National Ministry of Education, and these students were below average in terms of socioeconomic status. The remainders were middle class in socioeconomic status. Even though the school in which the current study was conducted was located in the city of Trabzon, it was one of the first schools in which contemporary science curricula such as CHEMS, Nuffield, etc. were implemented. Therefore, its laboratory equipment was of a high standard. However, informal interviews with students suggested that teachers rarely used the equipment to improve teaching. The sample’s elementary school achievement levels ranged from 3.36 to 4.85, with a maximum possible score of 5.00. In Turkey, topics “properties of matter, naming compounds, mole concept, solubility, variables affecting solubility, separation of mixtures and compounds, periodic table and its properties, atoms and molecules, chemical bonding and intermolecular forces” are taught at this level. The students under investigation were introduced to the topics “properties of matter,

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separation of mixtures and compound, mole concept, and naming compounds” before the intervention, which is now described below. The Teaching Intervention Since the aim of this paper was to investigate the applicability of an analogy activity used by Çalık & Ayas (2005a), the teaching procedure the current work draws upon is a similar four-step constructivist teaching strategy. Before outlining the analogy activity, we note that a solution can be both saturated and dilute, as well as both unsaturated and concentrated. However, such points are not taught at grade 9 within the Turkish chemistry curriculum. The analogy activity used as the intervention in this work involves travel on a public bus; a very common experience for school age children in Turkey: Please read the following case carefully and then fill in the schema provided: 1. Think of a bus, whose capacity is 40 when full, with 25 men who sit down together (bus stop 1) 2. Four women (bus stop 2), five women (bus stop 3) and six women (bus stop 4) get on the bus at each of the subsequent bus stops, respectively, and sit down amongst the men 3. After reaching full capacity, the driver notices five women who are hitchhiking but there are no seats left. She/he is not keen on leaving them in the intense sunshine and picks them up. Finally, the women get on the bus (bus stop 5), and sit down on seats amongst the men as in case of the other bus stops. 4. Then, the women who get on at bus stop 5, get off at the subsequent one. 5. Taking into account the given story, please fill in the subsequent schema by counting the percentages of women per men.

The numbers of passengers Men Women

Bus Stop 1

%

Bus Stop 2

%

Bus Stop 3

%

Bus Stop 4

%

Bus Stop 5

%

Bus Stop 6

%

Students worked in small groups to explore their pre-existing notions. In this process, the teacher sought to clarify parts of the analogy students did not understand, but refrained from giving any clues to the answers. Thus,

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students worked in an interpretive environment to elaborate their ideas by discussing them in their groups. Then, the teacher led a class discussion in order to confirm or disconfirm students’ newly structured notions by using an analogical map that indicated like and unlike points between the analog and target conception (see Çalık & Ayas, 2005a). The Four-Step Constructivist Teaching Strategy The four-step constructivist strategy is described in more detail in our prior work (Çalık & Ayas, 2005a; Çalık, Ayas, Coll, Ünal & Coştu, 2007) and is only briefly described here. The strategy is comprised of: (1) eliciting students’ pre-existing knowledge so that before carrying out the activity, the students’ pre-existing ideas are drawn out and integrated with the task, (2) focusing, where students engage in the devised task and try to achieve conceptual understanding, (3) challenging, where after students came up with agreement within their groups, a wholeclass discussion is carried out in order to confirm/disconfirm students’ prior ideas and (4) applying (fruitfulness), where students tackle applying their experience to another different situation in order to reenforce their new knowledge (see Çalık & Ayas, 2005a; Çalık, Ayas, Coll, Ünal & Coştu, 2007). Data Collection Procedures Data collection consisted of two designed test items based on line drawings, one-on-one interviews, and student self-assessment. This process provided data for triangulation as recommended in the literature (Harrison & Treagust, 2001), and was consistent with the interpretive nature of the study. The test items used were based on previous work, which had probed Turkish students’ understanding of solution chemistry (Çalık, 2003). The two items used as probes are shown in the following figures and accompanying text. ITEM 1. Table salt item used to probe students’ understanding of saturated solutions

The solubility of table salt (NaCl) is 35 g/100 ml at 18°C. In the above figure, each beaker contains 100 mL of water at the same temperature.

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Next 25 g, 35 g, and 40 g of table salt are added into the beakers, respectively, and the solution is stirred. The solution in Beaker C is first heated until all the table salt dissolves, and then is cooled back to the original temperature of 18°C. Please think about these three solutions, and say which term best describes them. Please provide reasons for your answer. ITEM 2. Table salt item used to probe students’ understanding of ‘dilute’ and ‘concentrated’ solutions

As can be seen from the above figure, the two beakers each contain 100 ml of water at the same temperature. Next, 2 g of table salt are added to the beakers, respectively, and the solutions stirred. Please think about these two solutions, and say which term best describes them. Please provide reasons for your answer. The items were used as a pre-test administered 1 month before the intervention. This was done fairly well in advance of instruction so as to reduce students’ familiarity with the questions. After completing ten activities (across eight class teaching periods), incorporating different types of solutions, the same test was employed as a post-test. Finally, to determine how the activity might help students’ retention of the scientific concepts in long-term memory, the same test was re-administered as a delayed post-test 10 weeks later, after the intervention. Some data are missing from the one-way ANOVA (that is, for S1, S2, S21, S22, S38 & S44) since some students did not take part in one of the tests, (see Tables 3, 4 & 6 below for details). Interviews were conducted with six students (two students S6 and S9 were of average ability, two, S8 and S25 of below average ability, and two, S16 and S42 of above average ability) on the basis of their elementary school achievement levels. These participants were selected purposively because they exhibited the largest total change for the solution chemistry probes based on their pre-test, post-test, and delayed post-test scores. The researchers in these interviews sought to probe student understanding and in particular their reasoning in depth. In each interview, students were firstly instructed to take two beakers and add 40 ml water to each. Then, students were asked to add a cube of sugar to one beaker and two cubes into the other. After completing these activities, they were probed using similar prompts as outlined above: “Please think

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about these two solutions, and say which term best describes them. Please provide reasons for your answer”. Next, another beaker containing 40 ml of water was taken and to this was added three sugar cubes. This beaker was first heated and then cooled. In this process, before asking the principal questions (i.e., those used above), the researchers emphasized that the students should remember that only two cubes of sugar were dissolved into 40 ml of cold water. Then the students were asked questions such as, “Please think about these two solutions, and say which term best describes them. Please provide reasons for your answer”, and “Is there any difference between “unsaturated, saturated and supersaturated solution and dilute and concentrate solutions” terms? Please give reasons for your answers”. These interviews each lasted 35–40 min. Student self-assessment was carried out after each activity. The 44 participants were asked to fill in a form based on their experiences—the form was that used by Çalık, Ayas & Coll (2006) (Fig. 1). Data Analysis Procedures In analyzing the student responses to the probe items, the following criteria were used: Sound Understanding (4 points), Partial Understanding (3 points), Partial Understanding with Specific Alternative Conception (2 points), Specific Alternative Conceptions (1 point) and No Understanding (0 point). The basis of this categorization was: 

Sound Understanding: Responses that included all components of the validated response.  Partial Understanding: Responses that included at least one of the components of the validated response, but not all the components.  Partial Understanding with Specific Alternative Conception: Responses that showed understanding of the concept but also made statements, which demonstrated an alternative conception.

Figure 1. Student self-assessment form used in the study

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Specific Alternative Conceptions: Responses that included illogical or incorrect information.  No Understanding: Repeats question; irrelevant or unclear response; blank. The data from the interviews along with the student’s self-assessment were analyzed thematically, based on their similarities and differences (Merriam, 1988; Yin, 1994). Research Findings Results of Solution Concept Test for Item 1 and Item 2. As can be seen from Table 1, most of the students’ responses in the pre-test fall into the ‘No Understanding’ Category. However, in the post-test and delayed post-test this changed, and students’ responses labeled ‘Partial Understanding’ increased for item 1, and a similar trend was seen for item 2 in the ‘Partial Understanding with Specific Alternative Conception’ category. In both the post-test and the delayed post-test, students’ responses categorized under the ‘Sound Understanding’ category also increased. One-way ANOVA results of test data using a multiple comparisons (post-hoc test) (Sum of squares: 278,386; df: 2; Mean score: 139,193; F: 34,528; Sig.: 0.000) are presented in Table 2. As can be seen from Table 2, there is a statistically significant difference between the pre-test and post-test, and between the pre-test and

TABLE 1 Students’ responses for item 1 and item 2 (percentage) Item 1

Item 2

UL

Pre-test

Post-test

Delayed test

Pre-test

Post-test

Delayed test

SU PU PUSAC SAC NU MD

95.5 4.5

6.8 27.3 2.3 59.1 4.5

11.4 36.4 2.3 2.3 43.2 4.5

11.4 84.1 4.5

11.4 27.3 13.6 22.7 20.5 4.5

13.6 15.9 31.8 13.6 20.5 4.5

UL Understanding Level; SU Sound Understanding; PU Partial Understanding; PUSAC Partial Understanding with Specific Alternative Conception; SAC Specific Alternative Conceptions; NU No Understanding; MD Missing data incorporates student who did not participate in the test

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TABLE 2 Multiple comparisons’ (post-hoc test) results Tukey HSD (I) TEST

(J) TEST

Mean difference (I-J)

Std. error

Sig.

Pre-test

Post-test Delayed test Pre-test Delayed test Pre-test Post-test

-3.05 -3.53 3.05 -.47 3.53 .47

.46 .46 .46 .46 .46 .46

.000 .000 .000 .561 .000 .561

Post-test Delayed test

*The mean difference is significant at the. 05 level

delayed post-test scores (p G 0.05) in favor of the post-test and delayed post-test scores. However, there are no statistically significant differences between the post-test and delayed post-test scores (p 9 0.05). One of the aims of the paper was to monitor students’ conceptual change in an attempt to discern the basis on which this change occurred. Hence a detailed analysis of students’ responses for item 1, are illustrated in Table 3, to add to the depth of understanding of the students’ thinking. A similar analysis for item 2 is presented in Table 4. Findings from the Student Interviews. Students’ responses to the principal questions during interview sessions are presented in Table 5. To probe student’s responses in depth, follow-up questions were used depending on students’ initial responses. As an illustration of this process, student S9 responded to the initial prompt question when asked about the terminology of solutions, by identifying “saturated and supersaturated solutions”, and also mentioned the “dilute and concentrate solutions” terms. These initial responses were followed by questions such as: “why did you change your idea?” which resulted in no response, but the question was then asked “how did you decide to call them ‘saturated and dilute solutions?’, in other words, what is your criterion?” The response was that they were named based on the apparent rate of solubility and the student pointed out that “whereas rate of solubility in the dilute solution was faster, than that in the other solution which was slower”. Of the interview participants, only two (S16 & S42) compared dilute and concentrated solutions directly saying that the amount of solvent in each solution must be equal.

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To illustrate the student interviews associated with dilute and concentrated solutions an excerpt is presented below: (where R: Researcher; S9: Student 9) R: Based on your observations, compare the solution in Beaker A with that in Beaker B S9: The solvent is equal here…. Then we add two cubes of sugar into the water… Whereas the solution in which was added one cube of sugar is saturated, the other is supersaturated. R: What do you mean by ‘saturated solution’? S9: Saturated solution …… the same amount of matter is supplemented into the beaker… that is the amount that the solvent dissolves…. Namely, the solvent dissolves as much as it can R: What do you think about, whether or not these solutions are called by different terms? S9: We named them as dilute and concentrated R: What do you mean by ‘dilute solution’? S9: The solution whose soluble amount is less is dilute, and the solution, whose soluble amount is more, is concentrated R: Why did you change your idea? S9: ……… (no response)

As in case of ‘dilute and concentrated solutions’ concepts, to investigate students’ responses in depth and find out their reasons, follow-up questions were used to build on students’ initial responses. For example, when student S8 was prompted about his use of the terminology of solutions, he commented that the dissolution process in the unsaturated solution had, “still been continuing and not finished”, therefore, the “solutions including two cubes of sugar and three sugar cubes are unsaturated”, and “that the one containing one cube of sugar is saturated”. Likewise, probing student S25’s comments about saturated and unsaturated solutions in depth resulted in his depiction of dilute and unsaturated solutions being “equivalent because they can dissolve more solute and concentrate” and that “saturated solutions are also equivalent because they cannot dissolve more solute”. To illustrate students’ interviews related to ideas of unsaturated, saturated and supersaturated solutions and the difference between types of solutions, a transcript is presented below: R: Taking into account these three solutions, how did you label them?

PU

The solution in Beaker C is supersaturated because since its solubility is 35 g/100 ml, this solution which is heated and then cooled, incorporates much more solute, hence, it is a supersaturated solution -

When we look at the solubility amount, the solution in Beaker B is saturated because it already incorporates a maximum amount of solute that can dissolve. Beaker A includes less solute than it can dissolve so that it is an unsaturated solution. Beaker C not only contain much more solute than it can dissolve but also is heated and then cooled. Thereby, it is a supersaturated solution The solution in Beaker A is unsaturated; that in Beaker B, saturated and that in Beaker C is supersaturated

SU

Pre-test

Student’s responses

UL

-

-

-

% 6,8

%

S12*, S25

4,5

S6, S9, S21, S23, 20,5 S24*, S26, S32, S33, S39

S5, S7, S16

Post-test

In depth analysis of student responses for item 1 with respect to level of understanding

TABLE 3

11.4

%

S6, S9, S12, S17, 34.1 S18, S26, S28, S32, S33, S35, S37, S40*, S41, S42, S43 S10 2.3

S3, S5, S7, S16, S44*

Delayed test

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-

-

4.5

-

-

S34

S42

S1, S3, S4, S8, S10, S11, 59,1 S13- S15, S17-S20, S22, S27-S31, S35-S7, S40*, S41, S43, S44* S2*, S38 4,5

-

-

95.5

-

-

-

-

*These students did not take part in the analogy activity on types of solutions

Students who did not S22, S44 participate in the test

No Understanding

SAC

PUSAC

The solution in Beaker B is saturated because since its solubility 35 g/100 ml, it already includes 35 g of table salt Whilst solutions in Beaker A and Beaker B are less saturated solutions, that in Beaker C is supersaturated solution Thy solution in Beaker A is dilute; that in Beaker B is saturated and that in Beaker C is concentrate Beaker A and Beaker B are solutions, Beaker C is a half-solution because in the cooler water in Beaker C, table salt did not dissolve completely S1-S21, S23- S43 S38

S14

-

-

43,2 S2*, S4, S8, S11, S13, S15, S19, S20, S22-S25, S27, S29-S31, S34, S36, S39 S1, S21 4,5

-

-

2,3

2,3

2.3

2.3

-

-

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Taking into consideration the idea that the amount of water is equal, Beaker A, which includes less sugar, named as a solute, is a dilute solution. Also, Beaker B that incorporates more sugar, is a concentrate solution The solution in Beaker A contains less solute (sugar) than that in Beaker B

SU

PUSAC

The solution in Beaker A is dilute while that in Beaker B is a concentrate The solution in Beaker B contains more solute (sugar) than that in Beaker A, therefore, the solution in Beaker A is unsaturated The solution in Beaker A contains less solute (sugar) than that in Beaker B. Hence, the solution in Beaker B is a supersaturated solution The solution in Beaker A contains less solute (sugar) than that in Beaker B. Therefore, the solution in Beaker A is a less saturated solution compared to that in Beaker B

Student’s responses

UL

PU

TABLE 4

-

-

-

-

-

-

-

-

-

-

-

-

%

Pre-test

S43

S42

S5, S6, S9, S10

22,7

S3, S12*, S15, S19, S20, S21, S24*, S25, S29, S41 SÖ17, S26

2,3

2,3

9,1

4,5

11,4

%

S16, S32-S34, S36

Post-test

In depth analysis of student responses for item 2 with respect to level of understanding

-

S5, S9, S10, S11, S17, S20, S39, S43 S7, S38

-

S2, S3, S15, S19, S25, S30, S37

S6, S14, S16, S33, S36, S42

Delayed test

-

4,5

18,2

-

15,9

13,6

%

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S22, S44

The solution in Beaker A is saturated While the solution in Beaker A is saturated, that in Beaker B is more saturated Whilst the solution in Beaker A is unsaturated, that in Beaker B is saturated The solution in each beaker is heterogenic. Also, while the solution is Beaker A is saturated, that in Beaker B is supersaturated. S1-S5, S7, S8, S10, S14-S21, S23-S43

4.5

S8, S27, S28, S30, S31, S35, S37, S40*, S44* S2*, S38

-

-

84.1

-

-

-

-

6.8

S11, S12, S13

-

2.3

S9

-

2.3

-

S6

-

*These students did not take part in the analogy activity on types of solutions

Students who did not participate in the test

No Understanding

SAC

Since Beaker A incorporates less solute, its solution is dilute, whilst the solution in Beaker B is saturated. While the solution in Beaker A is saturated, that in Beaker B is supersaturated Whereas the solution in Beaker A is saturated, that in Beaker B is unsaturated Since each beaker includes sugar, both of them are the same solution. That is, no difference exists The solution in Beaker A is unsaturated

4,5

20,5

-

-

S1, S4, Ö7, S11, S18 S13, S39 S14, S22

-

-

S23

-

4,5

20,5

S8, S12*, S13, S27, S29, S31, S34, S41, S44* S1, S21

2,3

S40* -

4,5

4,5

-

-

-

9,1

2,3

S23, S24*

S4, S18

-

-

-

S26, S28, S32, S35

S22

-

4,5 4,5

11,4

-

-

2,3

-

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Solution incorporating two cubes of sugar is a concentrate and the other is dilute Whereas the solution with one added cube of sugar is dilute, the other is saturated Whilst the solution with an added cube of sugar is saturated, the other is unsaturated Whereas the solution with one added cube of sugar is saturated, the other is supersaturated While the solution containing two cubes of sugar is saturated, the other is unsaturated The solution, whose solute amount is less, is dilute and the solution, whose solute amount is more, is concentrate A dilute solution can dissolve more solute. However, a saturated solution cannot dissolve more if a bit more solute is dropped in The less a solution includes sugar the more it dissolves The solutions are saturated, unsaturated and fully saturated

Based on your observation, please think about these two solutions, and say which term best describes them.

Please give your reasons

Student’s response

Principal question

Students’ responses to the principal questions during interview sessions

TABLE 5

S25

S8

S6

S9, S16, S42

S25

S9

S8

S6

S16, S42

Student’s number

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Is the term “unsaturated solution” equivalent to “dilute solution”, and is a “concentrated solution” equivalent to a “saturated solution” ?

Do you see any difference between an “unsaturated, saturated and supersaturated solution” and the terms, and “dilute and concentrate solutions”? Please give your reasons

Taking into account these three solutions, what will you call them?

The solution incorporating one cube of sugar is unsaturated; that containing two cubes of sugar is saturated and that including three cubes of sugar is supersaturated The solution incorporating one cube of sugar is dilute; that containing two cubes of sugar is saturated and that including three cubes of sugar is concentrated The solution incorporating one cube of sugar is saturated and that including three cubes of sugar is unsaturated To determine unsaturated, saturated and supersaturated solutions, the solubility should be given To determine unsaturated, saturated and supersaturated solutions, the amount in 100 ml water should be given No response (quietness) To decide between unsaturated and saturated solutions, solubility should be known. On the other hand, to identify dilute and concentrate, we look at the amount of solvent which must be the same for each solution They differ from each other. In adding more solute into water, if it dissolves, it is a dilute solution. If more solute is available, it becomes a concentrate solution There is no difference amongst them No response (quietness) S25 S8

S6

S8, S25 S9, S16, S42

S6

S9, S16, S42

S8

S6

S9, S16, S25, S42

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S16: The solution incorporating one cube of sugar is unsaturated, that containing two cubes of sugar is saturated and that including three cubes is supersaturated R: Please explain your reasons S16: Because the solute for some water… that is, the amount of solute dissolving into the solvent is known. If added solute is less than this amount, it is unsaturated. If it incorporates enough solute that the solvent can dissolve, it is saturated…. if it contains more solute, it is supersaturated R: Is there any difference between the ‘unsaturated, saturated and supersaturated solution’ terms and the ‘dilute and concentrate solutions’ terms? S16: Whereas we look at the amount of solute in each solution for dilute and concentrate solutions, for the others we look at the known amount that the solvent dissolves a solute R: Please explain your reasons S16: The main difference… the amount of solute dissolving into 100 ml water R: What do we call this? S16: For example, for table salt, it is 36 g/100 ml… dissolving… dissolution… no… no… the solubility should be given R: Is an unsaturated solution equivalent to a dilute solution, or is a concentrated solution equivalent to a saturated solution? S16: No… of course… They differ from each other. In adding more solute into water, if it dissolves, it is a dilute solution. If more solute is available, it becomes a concentrated solution. I do not ever forget solubility….

Findings from the Students’ Self Assessment Exercise. The results of the students’ self-assessment exercise after completing the analogy activity are summarized in Table 6. As can be seen from Table 6, about half of the students felt that they learned ‘the differences between ‘unsaturated, saturated, and supersaturated solutions’ and the terms ‘dilute and concentrate solutions’. However, nearly half noted that they did not feel they understood the ‘unsaturated, saturated and supersaturated solution concepts’ and ‘dilute and concentrate solutions’ concepts. Additionally, approximately one fifth of the students said that descriptions of ‘dilute and concentrated solutions’ were relative, but, ‘unsaturated, saturated and supersaturated solutions’ concepts related to the actual solubility (i.e., the amount dissolved). Moreover, only three

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students depicted solubility as a feature that helps to discriminate one substance from another. DISCUSSION Results of the one-way ANOVA suggest that there are statistically significant differences for the test scores for this cohort of students. Also, as seen in Table 2, there are statistically significant differences between the pre-test and post-test and between the pre-test and delayed post-test scores (pG0.05) in favor of the post-test and delayed post-test. However, there are no statistically significant differences between the post-test and delayed post-test scores (p90.05). This suggests that this analogy activity helps students to construct their understanding of types of solutions in a manner that is more in accord with the scientific concept. Moreover, since there are statistically significant differences between the post-test and delayed post-test scores, it is reasonable to assume that the analogy activity has helped the students store these concepts in their long-term memory (Glynn & Takahashi, 1998; Hynd, Alvermann & Qian, 1997; Palmer, 2003; Tsai, 1999). These numerical findings are supported by the interview data and the student’s self-assessment exercise. Support for the value of the intervention comes from the fact that the science education literature reports that typically we can see minor decreases in students’ conceptual understanding over time after an intervention. However, in the case of the present work (see Table 1), it seems there is an increase in students’ understanding over the course of time (Coştu, 2006). This result may have occurred for two reasons. The first is that even though students may not construct their understanding properly after completing the analogy activity, in the course of time, the activity may afford the conditions for students to continue this construction process in their mind so that he/she may have continued to construct his/her understanding. The second may stem from the interaction between peers. Of note here is the nature of the intervention. As described above, the intervention consisted of an analogy and in particular, it drew upon a life experience that was very familiar to all students; namely, traveling on a public bus. The researchers also stressed points at which the analogy broke down. As seen in Table 1, most of the students did not initially answer these questions or provided irrelevant or unclear responses in the pre-test. One factor might be that the items used in this paper were located at the end of the Solution Concept Test (i.e., when administered as part of the research

22.7

6.8 2.3 13.6 4.5

21

23

10

3 1 6 2

Unsaturated, saturated and supersaturated solution concepts

Dilute and concentrate solutions

“Dilute and concentrate solution” descriptions are relative, but, “unsaturated, saturated and supersaturated solutions” concepts depend on the solubility amount Solubility is a feature that helps to discriminate one matter from the others Calculation of percentage and solubility I did not learn the following concepts involved in this activity I did not concentrate on the activity, Therefore, I did not learn the concepts under investigation Calculation of percentage and solubility

52.3

47.7

54.5

24

I learned the following concepts involved in this activity The difference between “unsaturated, saturated and supersaturated solution” terms and “dilute and concentrate solutions” terms

%

Frequency

Categories

The results of students’ self-assessment after the analogy activity

TABLE 6

S29, S41

S23, S28-S30, S35, S43

S11

S25, S31, S37

S3, S4, S6-S11, S13, S14, S16, S18-S21, S26, S27, S31, S33, S37-S39, S41, S42 S1, S3, S4, S8-S10, S14, S15, S17-S19, S21, S22, S25, S27, S33, S34, S36, S39, S41, S42 S1, S3-S5, S7-S10, S14, S15, S17-S21, S25, S27, S33, S34, S36, S39, S41, S42 S4-S6, S7, S9, S10, S19, S20, S21, S34

Student’s number

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described in Çalık, 2005). It is possible that by the time the students completed the 17 items, they were more reluctant to answer the last questions; or that may have somewhat less interest in completing tasks by this time. Secondly, although the four-step constructivist teaching strategy incorporating the analogy activity took into account students’ pre-existing ideas, it has some limitations in changing students’ alternative conceptions towards scientific conceptions (e.g., Guzzetti, Williams, Skeels & Wu, 1997; Hynd, Alvermann & Qian, 1997). For example, despite the fact that the majority of the students said that they felt they had learned the concepts in the analogy activity in the self-assessment exercise, they failed to change their alternative conceptions. It is also worthwhile to note that many students’ prior ideas as found in the first administration came under the ‘No Understanding’ category. Examination of students’ alternative conceptions in the post-test data allows some interesting observations. For example, one student (S34) seemed to understand the concept of a supersaturated solution, even though she did not use the scientific terms ‘saturated and unsaturated’, instead using the term “less saturated solution” (Çalık, 2003; 2005). This is probably just a reflection of this student failing to remember the correct scientific terms. Likewise, student S14 in the delayed post-test used terms such as ‘dilute, saturated and concentrated’ for the given phenomena as also occurred in student interviews (Table 5). This suggests that students may have difficulty in differentiating the terms, and perhaps the types of solutions (Çalık, 2003; 2005). Interestingly, one student (S38) used the term “half-solution” in her description of a supersaturated solution (Çalık, 2003, 2005). This may have resulted from a misinterpretation of the observation. Alternatively, it also may be a result of interaction between this student’s alternative conceptions. In support of this latter proposition, this student also used the term “melt”, suggesting the student holds an alternative conception of dissolution itself (i.e., in that it may be being confused with melting), which may have influenced his ideas about types of solutions. Similarly, student S40 described solutions in each beaker as “heterogenic” (see Table 4). This result supports the idea that alternative conceptions, that form part of an individual’s cognitive structures, interact with each other (Schmidt, 1997). An interesting and somewhat unexpected result is related to the modification of ideas of students who did not take part in the analogy activity of types of solution, however, they participated in the administered tests. The present work suggests that since these students did not carry out the analogy activity, their understanding level appears as a discrepancy in the way they changed from time to time (Tables 3 and 4).

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The data provided in Table 4 suggests that these students generally struggled to distinguish the terms and perhaps types of solutions. When two solutions are available, they decide the types of solutions based on a comparison. For example, if one solution contains less solute than another, the solutions are considered relative to each other, and subsequently labeled ‘unsaturated’ and ‘saturated’, or ‘saturated’ or ‘supersaturated’. A similar result is also seen in the interview sessions, supporting this proposition (Table 5). One notable observation found here is that in the pre-test some students seemed to believe that since all of the beakers contain sugar, they are all the same. Such an observation suggests that students have little idea about different types of solutions, even after having been taught the basic concepts of solution chemistry in grade 7. On a positive note, in the present work, it seems the analogy activity helped some students to overcome such a view. The interview data suggests that when discussing types of solutions, students tend to come up with an argument based on the rate or amount of a substance involved in dissolution (Table 5). For example, student S8 identified the types of solutions by considering whether or not dissolution continues. This suggests that this student placed more attention on the solute, which stays at the bottom of beaker, than dissolution process itself. As noted above, there was some evidence of students retaining alternative conceptions even after the intervention. For example, even though student S9 appeared to change some of her ideas in the tests, in the interviews, it became evident that she had sound ideas about dilute and concentrated solutions, but was not able to distinguish clearly between the terms. In other words, she seems to have understood these concepts only in a fragmented manner (Haidar, 1997). She was also unclear on what basis she had changed her ideas. Moreover, as can be seen from Table 6, six of the students did not appear to engage with the activity, meaning that they did not seem to learn the concepts under investigation. This could be because they were unable to perform some simple mathematical calculations such as the calculation of percentage (this was supported by some unobtrusive observations). In spite of this latter observation, for these students, some did appear to improve in their understanding. For example, student S23’s response for the post-test and students S28, S35, and S43’s responses for the delayed post-test were categorized under the ‘Partial Understanding’ category. There are two reasons why this may have occurred. The first is that in spite of the fact that students felt that they did not learn much about the concepts, they may have progressed in their understanding to some extent as a result of their interaction with their peers or as an effect of the analogy activity on

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their long-term memory. Second, even though the researchers asked the students to write down their own ideas and stressed that it was important for them not to copy their friends’ ideas, they may nonetheless have copied in some cases. The main purpose of the full-bus analogy activity is to help students to distinguish between unsaturated, saturated, and supersaturated solutions, and to understand aspects of solubility, to identify dilute and concentrated solutions, and be aware that the amount of solvent must be the same for each solution when doing such comparisons. The interview data suggest that four students (S6, S9, S16, & S42) were able to make such distinctions. Also, even though student S8 felt he learned to make such distinctions (see Table 6), he did not use these ideas in his interview. Student S25 likewise was unable to respond to the interview questions. Differences between student selfassessment and their responses in interviews and/or the probe items may stem from the implementation procedure of the student self-assessment form. This form was administered immediately after students had completed each activity, meaning that the students may have put down things they think they have learned, because they have just learned them. In light of the current study, it is suggested that before setting out on the implementation of an analogy activity such as that used in this work, numerical exercises such as calculation of percentages should be done first. In which case, students may be more willing to participate in such activities. Finally, if student self-assessment is to be used, the time of its implementation should be thought carefully. ACKNOWLEDGEMENTS This study was supported by Research Fund of Karadeniz Technical University, Project Number: 2005.116.002.1. REFERENCES Brown, D.E. (1993). Refocusing core intuitions: A concretizing role for analogy in conceptual change. Journal of Research in Science Teaching, 30, 1273–1290. Brown, D. & Clement, J. (1989). Overcoming misconceptions via analogical reasoning: Abstract transfer versus explanatory model construction. Instructional Science, 18, 237–261. Chiu, M.H. & Lin, J.W. (2002). Using multiple analogies for investigating fourth graders’ conceptual change in electricity. Chinese Journal of Research in Science Education, 10, 109–134.

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Wheatley, G.H. (1991). Constructivist perspectives on science and mathematics learning. Science Education, 75(1), 9–21. Muammer Çalik KTU, Fatih Faculty of Education Department of Primary Teacher Education 61335, Söğütlü-Trabzon, Turkey E-mail: [email protected] Alipaşa Ayas Fatih Faculty of Education Department of Secondary Science and Mathematics Education 61335, Söğütlü–Trabzon, Turkey Richard K. Coll Centre for Science & Technology Education Research University of Waikato Hamilton, New Zealand