Neslihan
Ültay
*a,
Ümmü Gülsüm
Durukan
a and
Eser
Ültay
b
aGiresun University, Faculty of Education, Department of Elementary Education, 28200 Giresun, Turkey. E-mail: neslihanultay@gmail.com; Fax: +90 454 3101287; Tel: +90 454 3101270
bGiresun University, Vocational School of Health Services, 28200 Giresun, Turkey
First published on 30th September 2014
This study aimed to investigate the effect of conceptual change text (CCT) in the REACT strategy for students' conceptions of solutions. A quasi-experimental method was used in the study. The study was carried out in the spring term of the 2012–2013 academic year with 61 freshmen students (aged 18–20 years) studying in the Elementary Education Department. To gather data, the solutions concept test (SCT) was used as a pretest (PrT) and posttest (PoT) and clinical interviews were used to increase the validity of the data obtained from SCT. In the experimental and control groups, the REACT strategy was used as the teaching strategy. In the experimental group, the REACT strategy was enriched with CCTs. Three CCTs were used for the experimental group. According to the findings, there was a significant difference between the experimental and control groups' PrT and PoT results. The REACT strategy was found to be successful at dealing with the alternative conceptions in solution chemistry. However, no significant difference was found between the groups' PoT results. On the other hand, qualitative analyses showed that the CCTs were slightly effective in remediation of alternative conceptions in solution chemistry. This suggests that we may need to use more than one intervention model to effectively remedy the alternative conceptions in solution chemistry. This study may be helpful for diagnosing alternative conceptions and guide researchers to remedy them. Hence, CCTs can be designed for other chemistry topics for implementation in schools.
One of the goals of context-based science instruction is to increase the engagement of students so that they develop a greater interest in science (Fensham, 2009; Ültay and Ültay, 2014). Looking at the literature on the effect of context-based science instruction, it can be seen that some of the studies indicate an increase in success (Ingram, 2003; Schwartz-Bloom and Halpin, 2003; Demircioğlu, 2008; Acar and Yaman, 2011) and a positive effect on students' attitudes and motivation (Barker and Millar, 2000; Campbell et al., 2000; Ingram, 2003; Belt et al., 2005; Bennett and Lubben, 2006). To implement the context-based approach to the learning-teaching process, one of the strategies is the REACT strategy (Crawford, 2001). The REACT strategy is based on the context-based approach and uses five essential forms of learning. These elements are: Relating, Experiencing, Applying, Cooperating and Transferring. At the “Relating” stage new information is related to everyday situations. The “Experiencing” stage points out learning in the context of exploration, discovery and invention. The aim is to allow students to experience activities that are directly related to real life work. At the “Applying” stage, students apply concepts and information in a useful context through projects, activities, labs, text, and video. The “Cooperating” stage points out learning in the context of sharing, responding and communicating with other learners. This can be actualized via group activities such as projects, labs, problem-solving, realistic scenarios. At the “Transferring” stage, students transfer skills and knowledge from one setting to another (CORD, 1999). Ingram (2003) described the REACT strategy as being grounded on the basis of constructivism, in which students apply critical thinking and problem solving activities in order to improve their understanding of concepts. The REACT strategy has been used in science education literature to understand the concepts of impulse and momentum (Ültay, 2012a), acids and bases (Demircioğlu et al., 2012; Ültay, 2012b), and the particulate nature of matter and heat (Aktaş, 2013). The common finding of these studies was that the REACT strategy was shown to be successful at remedying the misunderstanding of scientific concepts by using materials from daily life and the relevant context to attract students' interest in a topic.
In this study, because the REACT strategy is a way of implementing the context-based approach in the classroom environment, the REACT strategy was preferred as a teaching model in both experimental and control groups. In the experimental group, the REACT strategy was enriched with conceptual change text (CCT).
CCT is a teaching material based on the conceptual change approach and is designed to remedy misconceptions. The use of CCT is more scientifically accurate in crowded classrooms because it is difficult for teacher–student and student–student interactions to effectively bring about conceptual change in small sized classes (Chambers and Andre, 1997). At the beginning of the CCT, students are asked to make predictions or a situation is proposed to activate the students' prior knowledge. Thus, students are asked explicitly to predict what would happen in the given situation before the information that demonstrates the inconsistency between common alternative conceptions and the scientific conceptions is presented (Hynd and Alvermann, 1986). These texts are provided to make students aware of the inadequacies of their existing knowledge and to create conceptual conflict or cognitive conflict (Dreyfus et al., 1990; Kim and Van Dunsen, 1998). The strategy is based on the activation of the students' alternative conceptions. Then the common alternative conceptions are given and the reasons why these alternative conceptions are far away from the scientifically accepted expressions are presented. Thus students feel the need to question their existing knowledge, are made aware of their own lack of knowledge and read the explanation of the scientific concept (Hynd, 2001). At the end of the CCT, the teacher provides a discussion environment to enable the students to comprehend the scientific concepts taught (Chambers and Andre, 1997; Pınarbaşı et al., 2006; Sevim, 2007). CCTs can also be integrated with the Predict–Observe–Explain (POE) technique. Because CCTs begin with a prediction question, students answer the question by making predictions with their existing knowledge. In order to observe the scientific explanation of the case, they perform an activity revealing the new knowledge's plausibility and intelligibility. After that students can explain the questioned case scientifically. In this study, some of the CCTs were used in this way. By using the POE technique, students have an opportunity to use their knowledge in the laboratory (White and Gunstone, 1992) and to see that their knowledge does not solve existing problems. CCTs were found to be successful in achieving conceptual change in various studies (Wang and Andre, 1991; Guzzetti, 2000; Ünal, 2007; Özmen et al., 2009). Similar results were obtained in many previously published studies (Maria and MacGinitie, 1987; Chambers and Andre, 1997), for instance Guzzetti (2000) stated that CCTs are one of the best strategies for providing conceptual change and for making permanent conceptual changes. On the other hand, when we took an in-depth look at the studies which used CCTs for conceptual change, we saw that in almost all of the studies there was one experimental group which was being taught using a CCT, and one control group which was being taught by means of traditional instruction (in other words teachers used a board to teach and students memorized the facts, i.e. no intervention method was integrated with the teaching). It is known that traditional instruction has been found to be ineffective in conceptual change and remedying alternative conceptions (Westbrook and Marek, 1991; Hewson, 1992; Harrison and Treagust, 2001; Hewson and Hewson, 2003; Palmer, 2003). Because of this, almost all of the studies concerning the effect of CCT for conceptual change compared a class taught with a CCT with a class in which no intervention method was used and they always found a positive effect when CCTs were used. To date there has been a lack of study concerning the effect of CCTs with the newly developed REACT teaching strategy used in the current study.
Examination of the literature on the teaching and learning of ‘solubility’ concepts resulted in the identification of the following themes: (1) the solubility concept (Cosgrove and Osborne, 1981; Abraham et al., 1992, 1994; Ebenezer and Erickson, 1996), (2) the nature of solutions (Fensham and Fensham, 1987; Prieto et al., 1989), (3) strategies to overcome alternative conceptions about solution chemistry (Johnson and Scott, 1991; Ebenezer and Gaskell, 1995; Taylor and Coll, 1997; Ebenezer, 2001; Kabapınar et al., 2004), and (4) discovering alternative conceptions (Smith and Metz, 1996; Case and Fraser, 1999). These studies have shown that students have several alternative conceptions about solution chemistry. The alternative conceptions identified by previous research are summarized in Table 1.
Alternative conception | Studies |
---|---|
The concept of dissolution is confused with that of melting | Stavy (1990), Goodwin (2002), Çalık et al. (2007), Sevim (2007) |
Dissolution believed to occur because of the use of hot solvent | Çalık et al. (2007), Sevim (2007) |
Assuming that mixing increases solubility | Blanco and Prieto (1997), Ebenezer and Fraser (2001), Pınarbaşı et al. (2006) |
Accumulation of salt at the bottom of the plate is an example of an heterogeneous solution instead of a supersaturated solution | Çalık (2005), Sevim (2007) |
The volume of the particle affects the solubility rate | Gennaro (1981), Ebenezer and Erickson (1996), Çalık et al. (2007) |
The reason why different liquids do not dissolve in each other is the difference in their densities | Ebenezer and Gaskell (1995), Pınarbaşı et al. (2006) |
The amount of solute affects the solubility | Ebenezer and Fraser (2001), Liu et al. (2002) |
Total mass is not conserved during the dissolution | Piaget and Inhelder (1974), Driver and Russell (1982), Holding (1987), Çalık et al. (2007) |
A solution containing undissolved solute is a supersaturated solution. | Pınarbaşı et al. (2006) |
Water plays the major role in the dissolution process | Uzuntiryaki and Geban (2005) |
Because solution chemistry plays a key role in the understanding of other related topics such as solubility equilibrium, electrochemistry, particulate nature of matter etc., this study focused on solution chemistry and the correction of alternative conceptions via CCT in the REACT strategy. However, there are lots of alternative conceptions about solution chemistry in the literature, therefore in this study we implied common alternative conceptions, namely (i) students confuse the concepts of dissolution and melting, (ii) when two different soluble particles are added to the same solution the solution becomes supersaturated, (iii) the volume of a particle affects its solubility rate, (iv) a concentrated solutions is defined as a solution in which the amount of solute is greater than that of the solvent, and (v) total mass is not conserved during dissolution.
The students in the experimental and control groups did not participate such an experimental design before. The first researcher was the students’ instructor of the General Chemistry course and she asked the students about their willingness to participate in the study. She assured the students that they were not obliged to participate in the study and that they would not be awarded extra points for their participation. The consent of the participants was requested before their responses in the interview were shared with the reader. Also, the participants were informed about sharing some demographic information and their consent was requested beforehand. Before and after the interviews, some of the dialogue between the researchers and the participants were not reflected in the study and remained between the two because of the principles of privacy and confidentiality. Some students (one student in the control group, one student in the experimental group) did not want to participate in the study and their data were not used in the study. The rest of the students willingly participated in the study.
In the clinical interviews, students were asked 12 questions about solutions. For the clinical interviews, firstly the students who scored the highest and the lowest points were identified, and then they were asked to participate in the interviews. In the experimental and control groups, three students from the upper group and three students from the lower group were interviewed. After identifying the students for the clinical interview, one student in the experimental group did not want to participate in the interviews. The researchers had to approve his leaving from the interview. Finally, 5 students (2 from the upper, 3 from the lower group) in the experimental group, 6 students (3 from the upper and 3 from the lower group) in the control group participated in the interviews. The first researcher carried out all of the interviews and each interview lasted approximately 20–25 minutes. Interviews were recorded with the consent of the interviewees, and then the recordings were written and analyzed. Some sample items from the SCT and the clinical interviews are given in Appendix 1.
The distribution of the concepts questioned in the SCT and the clinical interviews according to the question numbers and the relation of these concepts with the CCTs are given in Table 2. Some concepts, such as, dissolution, saturated, unsaturated and supersaturated solutions, dilute and concentrated solutions, factors affecting the solution rate, and factors affecting the solubility, were tested by asking more than one question. The questions in the SCT and clinical interview focused on the same concepts. However, the reason of using clinical interviews was to increase the validity of the data obtained from the SCT (triangulation). Triangulation is a powerful technique that facilitates validation of data through cross verification from two or more sources (URL, 2014).
Concepts | Questions in the SCT | f | Questions in the clinical interview | f | CCT |
---|---|---|---|---|---|
Dissolution | 1, 2, 8 | 3 | A1, A2, A3, B1, B2, C1 | 5 | CCT1 and CCT2 |
Solution and its components | 10 | 1 | A3, A8, C2 | 3 | CCT1 and CCT2 |
Conservation of the total mass during the dissolution | 14 | 1 | A4 | 1 | |
Saturated, unsaturated and supersaturated solutions | 3, 9, 12 | 3 | A5, A6 | 2 | |
Dilute and concentrated solutions | 5, 7 | 2 | A5, A6 | 2 | |
Factors affection the solution rate | 6, 13 | 2 | A2, A7 | 2 | CCT3 |
Factors affecting the solubility | 4, 11, 13 | 3 | A7, C1 | 2 | CCT3 |
In the study, an informal observation method was also used via an observation form (consisting of Likert type and open-ended questions) by a science education expert. It was useful to learn how the intervention was progressing from a different educator's point of view. Because this observation form was used to explore the inoperative parts of the intervention, according to the observation data the researchers tried to fix missing or inoperative points in subsequent classes. Therefore, observation data analysis is not mentioned in here.
Three chemistry and two science educators for the SCT, and a chemistry educator, two science educators for the clinical interview questions ensured the appearance, readability and content validity. The interrater reliability coefficient (Cohen's Kappa) between the two chemistry educators was found to be 0.89 for the clinical interview. Also, a few students, in addition to the sample under investigation, were asked to read all the instruments and let the authors know about any unclear or not understandable points. Afterwards, some minor revisions were made to the items in the instruments. Overall, these procedures indicated that the instruments were able to measure the students' conceptions about solutions.
Qualitatively, in the analysis of the SCT and clinical interviews, students' answers were put into five categories: sound understanding, partial understanding, partial understanding with alternative conception, not understanding and empty/irrelevant (Abraham et al., 1992).
Sound understanding (SU-3 points): this category included students' explanations that were completely scientifically accurate.
Partial understanding (PU-2 points): this category included students' explanations which showed some part of the correct answer but did not contain wrong information or an alternative conception.
Partial understanding with alternative conception (PUSAC-1 point): this category included both true and false explanations provided by students and these answers could contain alternative conceptions.
Not understanding (NU-0 point): this category included students' false explanations which were inconsistent with the scientifically correct answer and these answers could contain some alternative conceptions.
Empty/irrelevant (E-0 point): this category included students' irrelevant or not understood answers. Students could leave the question empty.
Two chemistry educators not involved in the study answered the questions in the SCT and the scoring of the SCT was controlled by the same chemistry educators and similar results were obtained. The interrater reliability coefficient (Cohen's Kappa) between two chemistry educators was calculated as 0.92 for the SCT. Because one correct question was equal to 3 points in the SCT, the maximum point from the entire test was calculated as 42. Clinical interviews were not scored, only categorized into the previously mentioned understanding categories. The interrater reliability coefficient (Cohen's Kappa) between the two chemistry educators was calculated as 0.89 for the clinical interview.
To effectively use CCTs, some necessary conditions should be provided. The first and most significant condition in conceptual change is to make students aware of their own ideas about the topic (Kasap and Ültay, 2014). As students become aware of their own conceptions through presentation to others and by evaluation of those of their peers, they become dissatisfied with their own ideas; conceptual conflict begins to build. By recognizing the inadequacy of their conceptions, students become more open to changing them. After becoming dissatisfied with existing conceptions, the requirements for conceptual change are that the new conception be intelligible, plausible and fruitful (Posner et al., 1982). In this study, after introducing CCT2, firstly students were asked whether it was possible to get a heterogeneous solution if they added oil to water. Students wrote down their answer and tried to explain the reason for it. In this part, their thoughts were revealed about the question. After that, they read the “Students having the same thought have an alternative conception” sentence and then their possible alternative conceptions were apparent in CCT2. In case some of the students did not write an answer and explanation, they read the possible alternative conceptions in CCT2 and if they had one of the thoughts explained in there, their ideas became apparent. When their thoughts were apparent, the students started to become dissatisfied with their own ideas. Then, the students performed some hands-on activities showing the solubility of some substances in water and examples of solutions and mixtures in order for them to understand that their knowledge was useless and to create a conceptual conflict in their minds. When students recognized that it was not possible to obtain an heterogeneous solution, they felt that the new knowledge was intelligible and plausible. When students understood that solutions should have been seen as being homogeneous, they started to use “heterogeneous mixture” instead of “heterogeneous solution”. Thus, students found the new term fruitful because heterogeneous solution was not able to define the oil and water mixture. In this way, stages of conceptual change were carried out by the CCTs.
The first CCT (CCT1) was about the dissolution of sugar in water and was developed by Çalık (2006). CCT2 was about the types of solutions and CCT3 focused on the factors affecting the dissolution rate. CCT2 and CCT3 were developed by Sevim (2007). Specifically, CCT1 referred to the alternative conceptions of “Sugar melts not dissolves,” “Solute particles occupy the spaces between the solvent particles”, “A reaction takes place between sugar and water particles”. CCT2 focused on the alternative conception of “Oil and water can form an heterogeneous solution” and CCT3 focused on the alternative conceptions of “Stirring affects the solubility” and “Crushing of sugar particles increases the solubility of sugar in water”. After the implementation, the SCT was administered to both groups as a PoT. Then, the following week, the clinical interviews were carried out. An example outline of the teaching design in each group is given in Appendix 2.
To answer the first research question, descriptive data from the SCT is displayed in Table 3. As can be seen from the results presented in Table 3, the PrT scores obtained for the experimental and control groups are very similar. This is advantageous for the evaluation of the progress of the groups after the implementation. The PoT scores can also be seen to be quite close to each other.
Groups | N | PrT | PoT | ||
---|---|---|---|---|---|
Mean | Std deviation | Mean | Std deviation | ||
a PrT: pre test, PoT: post test. | |||||
Experimental | 31 | 16.22 | 4.92 | 20.55 | 3.66 |
Control | 30 | 15.26 | 4.33 | 20.70 | 4.34 |
In order to use parametric tests in the analysis of the data, rather than using the sample consisting of 61 students, normal distribution was checked with the One-sample Kolmogorov Smirnov test and the test distribution was found to be normal (Table 4).
PrT exp. group | PoT exp. group | PrT Cont. group | PoT Cont. group | ||
---|---|---|---|---|---|
N | 31 | 31 | 30 | 30 | |
a Test distribution is normal. | |||||
Normal parametersa | Mean | 16.2258 | 20.5484 | 15.2667 | 20.7000 |
Std. deviation | 4.92416 | 3.66823 | 4.33059 | 4.34027 | |
Most extreme differences | Absolute | 0.092 | 0.150 | 0.118 | 0.122 |
Positive | 0.082 | 0.091 | 0.091 | 0.119 | |
Negative | −0.092 | −0.150 | −0.118 | −0.122 | |
Kolmogorov–Smirnov Z | 0.514 | 0.837 | 0.648 | 0.670 | |
Asymp. Sig. (2-tailed) | 0.954 | 0.486 | 0.795 | 0.761 |
Then, an independent samples t-test was done to either check the equality of variances or to identify the significant difference between the groups' PrT and PoT scores. Data obtained from the analysis are presented in Table 5.
Levene's test for equality of variances | |||||||
---|---|---|---|---|---|---|---|
F | Sig. | t | df | Sig. (2-tailed) | Mean difference | ||
PrT | Equal variances assumed | 1.190 | 0.28 | 0.81 | 59 | 0.42 | 0.96 |
Equal variances not assumed | 0.81 | 58.48 | 0.42 | 0.96 | |||
PoT | Equal variances assumed | 2.502 | 0.12 | −0.15 | 59 | 0.88 | −0.15 |
Equal variances not assumed | −0.15 | 56.74 | 0.88 | −0.15 |
According to Table 5, after equality of the variances was provided by the Levene's Test, it can seen that there is no significant difference between the groups' PrT and PoT scores. The effect size coefficient (Cohen's d) between the PoT scores of both groups was calculated as 0.04 (Ellis, 2009). The effect size is a quantitative measure of the magnitude of a treatment effect. In this study, the effect size (0.04) was ranked as small which means that the intervention's effect on the experimental group was small. A paired samples t-test was performed to determine that the groups' learned the topic significantly and the data is shown in Table 6.
Groups | Tests | t | df | Sig. (2-tailed) |
---|---|---|---|---|
Experimental | PrT–PoT | −4.98 | 30 | 0.00 |
Control | PrT–PoT | −7.21 | 29 | 0.00 |
As can be seen from the results presented in Table 6, there is a significant difference between the PrT and PoT scores of the groups. It can be said that the teaching methods in the experimental and control groups have had positive effects on the conceptual understanding of solutions chemistry. The reason for this situation may be the use of daily life materials by both groups following the REACT strategy. The REACT strategy was found to be effective in resulting in conceptual change because of the relevant contexts and daily life materials used (Aktaş, 2013). According to Ültay (2012b), the use of relevant contexts when the REACT strategy is followed improves students' interest in the course and they become more motivated to learn. Thus, they become more open to acquiring new knowledge. In addition, the REACT strategy has the potential of placing the knowledge on a need-to-know basis, students see the relation between the scientific content and daily life (Çatlıoğlu, 2010). On the other hand, there was no statistical difference between the experimental and control group, which means that using CCT in a context did not provide superiority for the experimental group statistically. It can also be understood from the effect size's being small. It can also be understood from the effect size being small. According to Guzzetti et al., (1995), CCTs and refutational texts can be effective for the students who have an average learning abilities but for the students having reading difficulties CCTs and refutational texts can be supported by discussions. This case may be valid for this study because some of the alternative conceptions about the factors affecting solubility and solubility rate were not remedied and conceptual change was found negative. This may have been overcome by focusing on CCT3 and discussing in detail.
Table 7 shows the distribution of students' answers in the SCT regarding the conceptual understanding levels defined earlier in the paper such as sound understanding, partial understanding, etc. in the PrT and PoT.
Group | Test | Categories | Questions | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | |||
a SU: sound understanding, PU: partial understanding, PUSAC: partial understanding with alternative conception, NU: not understanding, E: empty, irrelevant. | ||||||||||||||||
Experimental | PrT | SU | 0.00 | 25.81 | 70.97 | 0.00 | 9.68 | 9.68 | 0.00 | 0.00 | 12.90 | 0.00 | 35.48 | 3.23 | 0.00 | 0.00 |
PU | 48.39 | 41.94 | 9.68 | 48.39 | 25.81 | 25.81 | 41.94 | 35.48 | 3.23 | 48.39 | 16.13 | 19.35 | 0.00 | 6.45 | ||
PUSAC | 25.81 | 9.68 | 12.90 | 9.68 | 6.45 | 9.68 | 6.45 | 6.45 | 80.65 | 45.16 | 16.13 | 6.45 | 96.77 | 41.94 | ||
NU | 25.81 | 12.90 | 6.45 | 22.58 | 6.45 | 32.26 | 3.23 | 48.39 | 0.00 | 0.00 | 16.13 | 54.84 | 0.00 | 19.35 | ||
E | 0.00 | 9.68 | 0.00 | 22.58 | 51.61 | 22.58 | 48.39 | 9.68 | 3.23 | 6.45 | 16.13 | 16.13 | 3.23 | 29.03 | ||
PoT | SU | 0.00 | 12.90 | 45.16 | 6.45 | 25.81 | 22.58 | 12.90 | 3.23 | 45.16 | 0.00 | 67.74 | 6.45 | 19.35 | 0.00 | |
PU | 83.87 | 48.39 | 51.61 | 67.74 | 16.13 | 6.45 | 35.48 | 48.39 | 0.00 | 45.16 | 0.00 | 0.00 | 19.35 | 12.90 | ||
PUSAC | 12.90 | 6.45 | 3.23 | 6.45 | 45.16 | 29.03 | 48.39 | 0.00 | 54.84 | 54.84 | 6.45 | 0.00 | 61.29 | 54.84 | ||
NU | 3.23 | 29.03 | 0.00 | 16.13 | 6.45 | 38.71 | 3.23 | 45.16 | 0.00 | 0.00 | 19.35 | 93.55 | 0.00 | 25.81 | ||
E | 0.00 | 3.23 | 0.00 | 3.23 | 12.90 | 3.23 | 6.45 | 3.23 | 0.00 | 0.00 | 3.23 | 0.00 | 0.00 | 6.45 | ||
Control | PrT | SU | 0.00 | 3.33 | 23.33 | 0.00 | 10.00 | 6.67 | 3.33 | 0.00 | 3.33 | 0.00 | 33.33 | 3.33 | 0.00 | 0.00 |
PU | 46.67 | 33.33 | 63.33 | 63.33 | 33.33 | 40.00 | 33.33 | 46.67 | 0.00 | 66.67 | 10.00 | 10.00 | 3.33 | 0.00 | ||
PUSAC | 26.67 | 16.67 | 6.67 | 6.67 | 20.00 | 16.67 | 3.33 | 0.00 | 96.67 | 23.33 | 13.33 | 6.67 | 90.00 | 43.33 | ||
NU | 26.67 | 13.33 | 3.33 | 6.67 | 0.00 | 20.00 | 23.33 | 43.33 | 0.00 | 3.33 | 23.33 | 46.67 | 0.00 | 13.33 | ||
E | 0.00 | 33.33 | 3.33 | 23.33 | 36.67 | 16.67 | 36.67 | 10.00 | 0.00 | 6.67 | 20.00 | 33.33 | 6.67 | 43.33 | ||
PoT | SU | 10.00 | 3.33 | 53.33 | 3.33 | 33.33 | 6.67 | 23.33 | 0.00 | 53.33 | 0.00 | 56.67 | 33.33 | 6.67 | 0.00 | |
PU | 53.33 | 23.33 | 43.33 | 60.00 | 0.00 | 20.00 | 20.00 | 50.00 | 0.00 | 60.00 | 0.00 | 10.00 | 3.33 | 23.33 | ||
PUSAC | 26.67 | 40.00 | 3.33 | 16.67 | 40.00 | 36.67 | 26.67 | 13.33 | 46.67 | 40.00 | 23.33 | 3.33 | 90.00 | 70.00 | ||
NU | 10.00 | 40.00 | 0.00 | 3.33 | 0.00 | 30.00 | 20.00 | 36.67 | 0.00 | 0.00 | 16.67 | 40.00 | 0.00 | 0.00 | ||
E | 0.00 | 0.00 | 0.00 | 20.00 | 23.33 | 6.67 | 10.00 | 0.00 | 0.00 | 0.00 | 0.00 | 13.33 | 0.00 | 6.67 |
From Table 7, it can be seen that the PUSAC and NU percentages of some of the alternative conceptions decreased for the 1st, 3rd, 9th and 12th questions for the control group and the 1st, 3rd, 4th, 8th, 9th, 13th questions for the experimental group. The decrease in the percentage of answers containing alternative conceptions means that more conceptual learning had occurred in the experimental group. When the percentages of SU and PU categories are considered, it can seen that the percentages of 10 questions (1st, 3rd, 4th, 5th, 7th, 8th, 9th, 11th, 13th and 14th questions) increased for the experimental group, and 9 questions (1st, 3rd, 7th, 8th, 9th, 11th, 12th, 13th and 14th questions) for the control group. Table 8 shows the paired samples t-test results for each question in the PrT and PoT of the SCT for both groups and between the groups for the PoT.
Groups | Questions | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | |
a The significant difference at 0.05 level. b The significant difference in favor of the experimental group. c The significant difference in favor of the control group. | ||||||||||||||
Exp. (PrT–PoT) | 0.001a | 0.045a | 0.861 | 0.005a | 0.018a | 0.455 | 0.009a | 0.153 | 0.002a | 0.813 | 0.034a | 0.086 | 0.000a | 0.147 |
Cont. (PrT–PoT) | 0.017a | 0.895 | 0.013a | 0.442 | 0.228 | 0.396 | 0.022a | 0.227 | 0.000a | 0.823 | 0.086 | 0.004a | 0.083 | 0.000a |
Exp.–Cont. (PoT) | 0.022b | 0.035b | 0.746 | 0.515 | 0.014b | 0.637 | 0.567 | 0.790 | 0.705 | 0.253 | 0.630 | 0.001c | 0.022b | 0.022c |
In Table 8 is presented each question's development with regard to its implementation as determined by the paired samples t-test. It can be seen that in the experimental group, students learned the conceptions better in 8 questions (1st, 2nd, 4th, 5th, 7th, 9th, 11th and 13th); whereas for the control group students learned in 6 questions (1st, 3rd, 7th, 9th, 12th and 14th) which were statistically different at the 0.05 level. From the results, it can be understood that the REACT strategy was successful at bringing about a conceptual change of solution chemistry for both groups because both groups were taught with the REACT strategy. Because in the REACT strategy, the instructor should uncover students' beliefs and prior knowledge, then relate the content to materials from daily life in a relevant context, it is possible to adjust teaching in response to changing conceptions (Crawford, 2001). As can be seen from the results presented in Table 8, the experimental group learned statistically better than the control group for the 1st, 2nd, 5th and 13th questions; whereas the control group was found to be better for the 12th and 14th questions. The results showed that the experimental group students were slightly better than the control group students. CCT1 and CCT2 were related to the 1st and 2nd questions and CCT3 was related to the 13th question in the SCT and the performance of the experimental group was shown to be better for these questions. Because the experimental group was not found to be successful at all the questions in the SCT, but in some of them, it can be said that the CCTs were found to be moderately effective in remedying alternative conceptions in solution chemistry. In addition, it cannot be said that CCTs fully promote conceptual change. Rather, CCTs can make great contributions to effective teaching but they can be supported with classroom experiences (Pınarbaşı et al., 2006). Because in both groups, the relevant contexts and materials from daily life provided meaningful experiences, the real effects of CCTs could not have been understood. Therefore, it is suggested that further research is carried out focusing directly on the effect of CCTs in the REACT strategy versus traditional teaching in which the teacher teaches and the students listen and memorize the facts.
In Table 9, the distribution of students' answers in the clinical interview with regard to conceptual understanding levels such as sound understanding, partial understanding, etc. in the PrT and PoT is given.
Group | Categories | Questions | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | ||
a Note: five students from the experimental group, six students from the control group were interview. | |||||||||||||
Experimental | SU | 0 | 0 | 0 | 1 | 3 | 4 | 0 | 1 | 0 | 0 | 3 | 0 |
PU | 3 | 0 | 0 | 0 | 2 | 1 | 2 | 4 | 0 | 0 | 0 | 1 | |
PUSAC | 2 | 3 | 4 | 3 | 0 | 0 | 2 | 0 | 2 | 4 | 0 | 3 | |
NU | 0 | 2 | 1 | 1 | 0 | 0 | 1 | 0 | 3 | 1 | 1 | 0 | |
E | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | |
Control | SU | 0 | 1 | 0 | 1 | 2 | 4 | 0 | 1 | 0 | 1 | 2 | 0 |
PU | 3 | 0 | 0 | 1 | 2 | 0 | 3 | 2 | 0 | 2 | 0 | 4 | |
PUSAC | 2 | 2 | 4 | 2 | 2 | 2 | 3 | 3 | 5 | 2 | 0 | 2 | |
NU | 1 | 3 | 2 | 2 | 0 | 0 | 0 | 0 | 1 | 1 | 4 | 0 | |
E | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
According to Table 9, when we take into account the frequency of SU and PU categories, in the 1st, 5th, 6th, 8th and 11th questions, the experimental group students were found to be more successful at remedying the alternative conceptions which were examined in these questions. On the other hand, for the 2nd, 4th, 7th, 10th and 12th questions, the control group students were found to be more successful.
In terms of the percentage changes and the frequencies shown in Tables 7 and 8, the experimental group students were found to be slightly more successful than the control group students. However, statistical analysis did not compute a statistically meaningful difference between the groups; qualitative analysis may have shown a different result.
Table 10 summarizes the percentages of the students' alternative conceptions and their conceptual change rates in terms of the experimental and control groups. Fewer than 5% of the alternative conceptions are not presented because there may be a level of random error (e.g.Çalık, 2005). In Table 10, a conceptual change level greater than 15% is labelled as “major”, between 15–10% is labelled as “limited”, and less than 10% is labelled as “minor”. From the results, it can be seen that the experimental group was slightly better than the control group because there were 2 limited and 5 minor conceptual change levels, whereas the control group had 5 minor conceptual change levels.
Alternative conception | Experimental | CC | CC Level | Control | CC | CC Level | ||
---|---|---|---|---|---|---|---|---|
PrT | PoT | PrT | PoT | |||||
Students confused the concept of dissolution with that of melting. | 16.67 | 3.89 | +12.78 | Limited | 16.11 | 8.33 | +7.78 | Minor |
It was believed that dissolution occurs due to the use of hot solvent. | 10 | 6.67 | +3.33 | Minor | 6.67 | 10 | −3.33 | Negative |
It was assumed that mixing increases solubility. | 8.89 | 7.78 | +1.11 | Minor | 2.22 | 1.11 | +1.11 | Minor |
Accumulation of salt at the bottom of the plate is an example of an heterogeneous solution instead of a supersaturated solution. | 6.67 | — | +6.67 | Minor | 3.33 | — | +3.33 | Minor |
Water is a good substance for obtaining a dilute solution. | 3.33 | — | +3.33 | Minor | 6.67 | — | +6.67 | Minor |
The volume of the particle affects the solubility rate. | 3.33 | 17.11 | −13.78 | Negative | 6.67 | 10 | −3.33 | Negative |
When water is evaporated from a solution, the solution becomes diluted. | 3.33 | 3.33 | 0 | — | 13.33 | 10 | +3.33 | Minor |
When water is evaporated from a solution, the amount of solvent is decreased, and the solute is increased. | — | 43.33 | −43.33 | Negative | — | 16.67 | −16.67 | Negative |
Oil will be at the bottom because its volume is the densest. | 6.67 | — | +6.67 | Minor | — | — | 0 | — |
The amount of solute affects the solubility. | 3.33 | 33.90 | −30.57 | Negative | — | 33.90 | −33.90 | Negative |
When two different soluble particles are added to the same solution, the solution becomes supersaturated. | 43.33 | 90 | −46.67 | Negative | 44.78 | 36.67 | +8.11 | Minor |
When two different soluble particles are added to the same solution, the solution becomes unsaturated. | 16.67 | 3.33 | +13.34 | Limited | 6.67 | 3.33 | +3.34 | Minor |
Total mass is not conserved during dissolution. | 63.33 | 83.33 | −20 | Negative | 56.67 | 70 | −13.33 | Negative |
Table 11 shows the sample student quotations obtained from the clinical interviews about solution chemistry.
Question | Categories | Sample student quotations |
---|---|---|
A1. You add 100 g of water to two beakers and you put granulated sugar in the first beaker, and the same amount of powdered sugar in the second beaker. What do you expect to happen in the solutions? Please explain. | PU |
I expect granulated sugar and powdered sugar to dissolve in water homogenously. (E5, C2, C4)
I expect dissolution. (E2, E3, C1) |
PUSAC | Dissolution, powdered sugar will dissolve harder and its solubility is less than granulated sugar. (E4, C3, C5) | |
NU | I see melting, both substances melt in water. (C6) | |
A2. Were sugars lost from the beaker? Which disappeared faster? Why? | SU | Sugars are dissolved. Powdered sugar dissolved faster because its surface area is bigger than granulated sugar and this affects solubility rate. (C4) |
PUSAC |
Sugars are disappeared. Powdered sugar disappeared faster because its size is smaller. (E2, C1, C2)
Sugars are dissolved. Powdered sugar dissolved faster because its surface area is smaller. (E1) |
|
NU | Sugars are disappeared. Both sugars are disappeared at the same rate because their amounts are the same. (E3) | |
A3.What is the appearance of sugar water? Explain it by drawing. | PUSAC | (Drawing is missing.) It is homogeneous because sugar is dissolved in water (E2, E3, E4, E5, C1, C2, C4) |
NU |
(Drawing is missing.) It is heterogeneous. (C5)
(Drawing is missing.) Sugar melted and only water is seen. (C6) |
|
A4. Will the difference occur in the mass of the beakers before we add the sugar, add the sugar and after sugar disappears? How can you explain the difference may stem from? | SU |
No, dissolving does not change the mass of the solution. (E5)
No, sugar dissolves in water but it is not lost. (C4) |
PU | There is no difference in the masses. (C6) | |
PUSAC |
No, because sugar is disappeared. (E3)
The masses are the same but after adding sugar they are not equal because sugar dissolves and disappears. (C5) |
|
NU |
The mass will increase because the solute does not disappear. (E2)
The mass will increase because sugar is there although we can not see it. (C1) |
|
A5. What type of a solution do we get if we increase the amount of water to 150 g? Why? | SU | Unsaturated solution, because the amount of solvent is increased but the solute remains the same. (E4, C2) |
PU | Unsaturated solution. (E2, E5, C1) | |
PUSAC | Dilute solution because the amount of solvent is increased. (C3, C4) | |
A6. What type of a solution do we get if we increase the amount of sugar which accumulated in the bottom of the beaker? Why? | SU | Supersaturated solution because water dissolves the maximum amount of sugar and the rest of sugar accumulates in the bottom. (E1, E3, E4, E5, C1, C2, C5, C6) |
PU | Supersaturated solution, the appearance is heterogeneous. (E2) | |
PUSAC | Concentrated or supersaturated solution because the amount of solute is increased. (C4) | |
A7. What happens if we heat the sugar water solution? Please explain. | PU |
Temperature affects solubility and solubility rate. (E1)
Temperature affects solubility. (C6) |
PUSAC | Temperature affects solubility rate but does not affect solubility. (E4, E5, C2) | |
NU | Water evaporates and the sugar particles remain. (E3) | |
A8. For this solution, what are the solvent and dissolved substances? Why? | SU | Water is the solvent, sugar is the solute because the amount of water is more than sugar. (E1, C1) |
PU |
Water is the solvent, sugar is the solute. (E2, E3, E4, E5)
Water is the solvent, sugar is the solute because the physical change is occurred in sugar particles. (C2) |
|
PUSAC | Water is the solvent, sugar is the solute because sugar is disappeared. (C3, C4) | |
B1.What will the appearance of the solution be like if we add some alcohol to water? Explain it by drawing. | PUSAC |
(Drawing is missing.) Alcohol dissolved in water homogeneously. (E2, E4, C1, C2, C4, C5)
(Drawing is missing.) Water is polar and alcohol is also polar. According to the rule of “Like dissolves like” water and alcohol dissolves in each other homogeneously. (C3) |
NU |
(Drawing is missing.) It seems heterogeneous. (E1, E3)
(Drawing is missing.) It seems heterogeneous, alcohol will be upper. (C6) |
|
B2. What will the appearance of this solution be like if we add some oil? Explain it by drawing. | SU | (Drawing is correct.) Because oil is nonpolar, it does not dissolve in alcohol and water solution. Also, the oil's density is lower than that of the alcohol and water solution, it will be upper. (C3) |
PU | (Drawing is correct.) It seems heterogeneous, alcohol dissolves in water but oil does not. (C1, C2) | |
PUSAC | (Drawing is correct.) Because the density of oil is lower than water and alcohol, it will be upper. (E2, C4, C5) | |
NU | (Drawing is missing.) Because dwater > dalcohol > doil. (C5) | |
C1. How would you decide which substances dissolve and do not dissolve in the solutions? Why? | SU | Substance is grouped as polar or nonpolar then according to the rule of “Like dissolves like”, polar substances dissolve in polar solvents, nonpolar substances dissolve in nonpolar substances. (E1, E2, E4, C3, C4) |
NU |
We put the substances together. If one of the substances reacts with the other, then we can say it dissolved. (C5)
We control if the substance obeys the factors affecting solubility. (C2) |
|
C2. What daily life examples can you give for the solutions? For these solutions, what are the solvents and dissolved substances? Why? | PU | Sugar water, salt water, sugar tea. (E4, C4, C5) |
PUSAC | Coffee, sugar tea. Solvent is water, solute is coffee and sugar. When we add the substances, the substance which disappears is solute. (E2, C3) |
From the results presented in Table 10, it can be seen that students had deficiencies in understanding the conceptions about solution chemistry before the teaching intervention. After the intervention, as seen in the PoT results, some alternative conceptions were decreased except for “The volume of the particle affects the solubility rate”, “When water is evaporated from the solution, the amount of solvent is decreased, solute is increased”, “The amount of solute affects the solubility”, and “Total mass is not conserved during the dissolution”. When we look at the results in depth, students showed the alternative conception of “The volume of the particle affects the solubility rate” (Gennaro, 1981; Ebenezer and Erickson, 1996; Çalık et al., 2007) in the PoT more than in the PrT. Some sample student quotations are as follows:
In PrT: The surface area of the particle affects the solubility rate (SU, E26 and C6).
Smaller particles dissolve slowly (NU, C12).
In PoT: The size of the particle affects the solubility rate for example bigger particles dissolve faster (PUSAC, E26).
Smaller particles dissolve faster because their surface areas are smaller (PUSAC, C6)
The surface area of the particle affects the solubility rate for example smaller particles dissolve faster (SU, C12).
Students thought that crushed particles dissolves faster because their surface areas are smaller (Çalık, 2005) but according to the experts crushed particles dissolves faster because their surface area is bigger than that of uncrushed particles. The reason the students' thought this may stem from the fact that they did not consider the surface area of each particle because in crushed particles, there are a lot of particles and when the surface area of each particle is summed, the total area is bigger than that of uncrushed particles. In fact, there were some activities which included crushed and uncrushed particles' solubility in the same solvent (namely, sugar was used as the example) in the intervention. It is quite interesting that some students had given an acceptable answer in PrT, while they changed their answers to the PUSAC category in PoT. This makes us think that students may have misinterpreted their observations about the surface area of the particles in relation to the solubility in the activities. As a matter of fact, according to Table 11, in the clinical interviews students showed this case by saying that powdered sugar had dissolved faster because its surface area was smaller from the results of the A2 question. Similarly and possibly because of the same thoughts, in the experimental group CCT3 was used to remedy the alternative conception of the factors affecting solubility in the 6th question of the SCT, it was not found effective to remedy that alternative conception. In the control group, students did not change their ideas with respect to the PrT.
The alternative conception of “When water is evaporated in the solution, the amount of solvent is decreased, solute is increased” increased in percentage after the intervention. Some sample student quotations are as follows:
In PrT: When water is evaporated, the soup becomes concentrated (PU, E2 and C19)
When water is evaporated, the soup becomes diluted (NU, E6).
In PoT: When water is evaporated, the soup becomes concentrated because more particles remain in the soup (PUSAC, E2).
When water is evaporated, the soup becomes unsaturated because the amount of salt decreases (PUSAC, C19).
When water is evaporated, the soup becomes concentrated because the amount of solvent decreases and the amount of the solute remains constant (SU, E6).
For this alternative conception, in the experimental group there was no special intervention activity to remedy it other than in the control group. But in both groups, the students were given a work sheet, which focused on the types of solutions, to study. However, this was not particularly effective at providing a remedy for this alternative conception. The reason for this may be that students confused the amount of solute or solvent with the ratio of solute to the solvent. When water evaporates the ratio of solute to solution changes but the students could not have been successful at establishing this relation. They thought that when water evaporates, the amount of solvent decreases and the amount of solute increases. But the amount of solute does not change; the change is only seen in the ratio.
Another alternative conception was found to increase in the PrT, “The amount of solute affects the solubility”. Some sample student quotations are as follows:
In PrT: Water should be added to the soup because when the amount of the solvent is increased, the rest of the salt can be dissolved (PU, E20).
The soup should be stirred because the salt is not dissolved (NU, E1).
In PoT: When the amount of the solvent is increased, the solubility of salt is increased (PUSAC, E20).
Water should be added to the soup because the rest of the salt can be dissolved (PU, E1).
The reason may be the same as for the previous alternative conception. Because students are not successful at understanding that solubility is not related to the amount of the solute or the solvent but is related to the ratio of solute to the solvent, they could not have shown good performance for this alternative conception. Another reason may be that students could not have constructed the knowledge well about the solubility and the factors affecting solubility (Ebenezer and Fraser, 2001; Liu et al., 2002). On the other hand, the results are still surprising because both groups showed this alternative conception in the PoT more than in the PrT. As mentioned previously, the students probably confused the amount of the solute with the ratio of solute to the solvent. But it is known that alternative conceptions consistently interact with other conceptions in the human mind because they are also parts of the thinking system (Çalık, 2003). Therefore, alternative conceptions existing in the students' minds may have resulted in new alternative conceptions, especially in the control group.
“Total mass is not conserved during the dissolution” (Piaget and Inhelder, 1974; Driver and Russell, 1982; Holding, 1987; Çalık et al., 2007) is the other alternative conception which was increased despite the intervention. Some sample student quotations are as follows:
In PrT: Mass is not changed (PU, E27).
When the particle is dissolved, the mass is increased (NU, E7, C1).
In PoT: Total mass is decreased (PUSAC, E27).
Total mass is increased (NU, E7).
Total mass is not changed when we add salt to water, it dissolves, but mass is changed when we add a ball to water because it is not dissolved (PUSAC, C1).
The reason for this case may be that the students thought that when a particle is dissolved in a solution, it cannot be seen any more, so the total mass is decreased because the particle has disappeared. Students explained the case in the clinical interview (see Table 11, question A4). While the intervention was carried out, students in both groups weighed the beakers before and after the dissolution; they saw that there was no difference between the two measures. But according to the PoT results, it could have been understood that they could not have internalized the new knowledge.
Students showed good performance and improvements for the correction of some alternative conceptions. For example “students confused dissolution with melting”. For this alternative conception, conceptual change was calculated as 12.78 for the experimental group and 7.78 for the control group. In the experimental group, conceptual change occurred more than for the control group. The reason for this may be CCT1 because it contained all the aspects of the alternative conception. However, in the C1 question of the clinical interview, the number of students in the experimental group (3 students) was greater than that of the control group (2 students).On the other hand, for both groups the alternative conception was not fully remedied because the students failed to distinguish the terms “melting” and “dissolution” (Stavy, 1990; Goodwin, 2002; Çalık et al., 2007; Sevim, 2007). There may be some discrepancies in the transfer of students’ knowledge from the macroscopic level to the microscopic level. When answering the A3 and B1 questions of the clinical interview, the students failed to draw solutions at the microscopic level. There were no students whose answers were counted as SU and PU categories. Additionally, students may have had some dilemma regarding chemistry language and daily life (Prieto et al., 1989; Longden et al., 1991). Çalık (2005) explained this situation in his study; when students are asked in school what they know, they tend to use ‘chemical’ or ‘scientific’ language. In contrast, outside of school, they tend to use their daily life experiences and more common language. This case is defined as dual conception (Gilbert et al., 1982). However, in the clinical interview some of the students expressed their ideas about question A1 “sugar dissolved, I mean it melted”, they showed their dual conception. However, Goodwin (2002) argues that when the dissolution process involves incorporation of solid mixtures of two or more substances, the terms ‘melt’ and ‘dissolve’ may be used interchangeably.
Students may have associated the concept of dissolution with that of melting because melting involves heat (Çalık et al., 2007; Sevim, 2007). For this reason, some students believed that “dissolution occurred due to the hot solvent”. Some sample student quotations are as follows:
In PrT: Dissolving because salt dissolves in liquids (PU, C14).
It dissolves because the soup is hot, salt can be melted in hot water (NU, E6).
In PoT: Dissolving because the soup is hot, salt can be melted in hot water (PUSAC, C14).
It dissolves because the soup is hot, salt can be melted in hot water (NU, E6).
In the PoT, the control group students related that dissolution occurred due to the hot solvent, while they had not related in the PrT. The reason for this not being observed for the experimental group could be that CCT1 and CCT2 were effective. However, in the case of the control group, although some activities were carried out which included hot and cold solvent with the same solute, this was not strongly emphasised and the students related dissolution with melting firstly and then melting with the temperature. Because the thoughts in students' minds are constantly interacting with other thoughts, the students who had given more acceptable answers in the PrT tried to explain the dissolution in relation to the hot solvent. This alternative conception may also result in the first alternative conception. When answering question A7 of the clinical interview most of the students related temperature to solubility and solubility rate. Some students thought that “mixing increases solubility”. These students confused the factors affecting solubility and solubility rate. In addition, students associated the amounts of the particle with the solubility rate (Blanco and Prieto, 1997), in the clinical interview they stated that “Both sugars are disappeared at the same rate because their amounts are the same” when answering question A2. From the results presented in Table 10 it can be seen that more conceptual change occurred in the experimental group than in the control group. This may stem from the CCT3 which focused on the factors affecting solubility rate.
Students have a variety of alternative conceptions about the relationship between the number of dissolved particles and concentration such as saturated, unsaturated, supersaturated, concentrated and dilute solution types. In this study, the alternative conception “accumulation of salt at the bottom of the plate is an example of an heterogeneous solution instead of a supersaturated solution” was found as in other studies presented in the literature (Çalık, 2005; Sevim, 2007). The problem is that students thought that solutions can be heterogeneous. This alternative conception was remedied for both groups in the PrT. However, CCT2 focused directly on this subject and better results were not obtained for the experimental group.
Another alternative conception about supersaturated, saturated and unsaturated concepts is that “To add two different soluble particles into the one solution makes the solution supersaturated”. Some sample student quotations are as follows:
In PrT: Saturated solution, because the solubility of sugar and salt are different in water and water can dissolve them separately (SU, E20).
Unsaturated solution because water tries to dissolve them separately (NU, E7, C5).
In PoT: Supersaturated solution because when water dissolves salt, solution is saturated. When we add sugar, the solution becomes supersaturated (PUSAC, E20).
Supersaturated solution because too many particles are added (NU, C5).
Unsaturated solution because water tries to dissolve them separately (NU, E7).
From the results presented in Table 10, it can be seen that for the experimental group the percentage of this alternative conception is higher in the PoT than in the PrT. Despite the fact that in both groups, there were no activities focusing directly on this alternative conception, it is surprising that the conceptual change level was found to be minor in the control group and negative in the experimental group. This can be explained in terms of the personal characteristics of the students, some of them could not have internalized the knowledge about the dissolution process and from the new learning in the intervention they may have extrapolated to this alternative conception. Students could not have thought that one particle's solubility did not affect the other particle's solubility, even if both existed in the same solution. But students thought that when the solvent dissolved one of the solute, then it could not have dissolved a second solute. This case can be explained with another common alternative conception that is “students believed that solute particles occupy the spaces between the solvent particles”. Thus, when the first particle is dissolved in the solution, there is no space remaining for the second particle's dissolution, therefore, it remains at the bottom of the beaker and the solution is supersaturated. Some of the students called this solution unsaturated but they probably confused the terms and they called it unsaturated instead of supersaturated. In the second part of the worksheet covering saturated, unsaturated and supersaturated solutions students were asked to calculate the percentages of solute and solvent in different solutions. During this step, the researchers observed that some of the students in both groups wrote the solute's percentages in place of the solvent's percentages. In the following part of the worksheet, students were asked to label beakers as saturated, unsaturated and supersaturated. But because students confused the solute and solvent terms or they simply wrote them incorrectly by mistake, some of them labelled the beakers incorrectly. This situation lead us to conclude that the students had confused the terms or that they did not understand the solute and solvent terms.
The alternative conception that is “when water is evaporated in the solution, the solution becomes diluted”, was not remedied in the experimental group and remedied slightly in the control group. Students had difficulty in understanding dilution and concentration concepts because they may have confused the terminology of the concepts. Students sometimes try to use ideas from daily life to explain scientific conceptions, but they may not have a deep understanding of the scientific view which leads them to make inappropriate applications of daily life experiences and terminology to scientific matters. This case can be clearly seen in the clinical interview, in the answers to question A5, students confused unsaturated, saturated and dilute solutions. In the answers to question A6, students used supersaturated and concentrated solutions concepts interchangeably. Another alternative conception about dilution is that “water is a good substance to get a dilute solution”. Students related dilution to water because in many solutions water is used as a solvent. Students may have thought that to get a dilute solution, we should add water, because the solvent is water. For example in daily life, when students taste coffee or tea and it is very sweet, they add water to decrease the sweet taste. Also, during cooking a soup in a saucepan, when students taste the soup and it is very salty, they add water to the soup to decrease the salty taste. Because students often used water as a solvent to make solutions dilute they focused on water, when the solvent was changed, they did not recognize it as being a solvent. the solutions in which the solvent was different from the water may have confused the students. From the answers to questions A8 and C2 in the clinical interview, it can be seen that the students could have easily labelled the solute and the solvent because they believed that the solvent is always water. The teaching materials used for both groups failed to remedy this alternative conception. Because students mostly related the topic of solutions to daily life, they may have held deeply ingrained misconceptions which were too difficult to change (Lakatos, 1970).
In the experimental group, students had such an alternative conception that “oil will be at the bottom because its volume is the densest” that it was remedied after the intervention because in the experiencing part of the REACT strategy, they performed an experiment which involved the addition of water to oil, etc. and they saw that there was no relation between the density and solubility (Ebenezer and Gaskell, 1995). Because in the courses, the experimental group students understood how a dissolution process takes place and what factors may effect solubility, they gave up relating density and solubility. However, from the answers given for question B2 of the clinical interview it was shown that students were able to draw the appearance of the solution at a microscopic level by not mentioning the relation between density and solubility. For the control group students this alternative conception was not seen either in the PrT nor the PoT, so it is not appropriate to talk about its remediation.
From Table 2 it can be seen that CCT1 and CCT2 focused on the same alternative conceptions in questions 1, 2, 8 and 10 of the SCT. When Table 8 is considered to see how CCT1 and CCT2 affected the experimental group students' conceptual learning, it can be seen from the answers to the first question, which was about the process of dissolution, that both groups had learned significantly. But for the second question, the experimental group students performed better than the control group students. Thus it can be said that the second question of CCT1 and CCT2, which required the drawing of the dissolution process at the particle level, had a positive effect on students' learning. CCT3 was closely related to the 4, 6, 11 and 13th questions in the SCT (see Table 2). From the results presented in Table 8 for conceptual learning, it can be seen that CCT3 was effective for the 4, 11 and 13th questions for the experimental group. In this context, it can be said that whereas CCT1 and CCT2 have a limited effect on the related alternative conceptions, CCT3 has a more major effect on the related alternative conceptions. According to Table 7, the 6th (CCT3) and 10th (CCT1 and CCT2) questions in which CCTs were used to remedy their alternative conceptions could not have been remedied in both groups. So, it can be said that CCTs were not effective in providing remedies for some alternative conceptions because they were deeply ingrained and became even more so with time because a conceptual change method had not been applied. Therefore, they were resistant to change (Guzzetti, 2000) by means of one intervention.
When all the factors are taken into consideration, it can be seen that both groups' conceptual learning was enhanced significantly both quantitatively (Table 6) and qualitatively (Table 10). From this, it can be said the REACT strategy was found to be effective in remedying alternative conceptions of solution chemistry. Numerous studies (Çatlıoğlu, 2010; Saka, 2011; Aktaş, 2013) have been conducted which have revealed, with empirical data, that the REACT strategy increases the motivation of students. Hence, students' conceptual learning is affected positively. Pintrich et al. (1993) argued that motivational factors play a key role as moderators of conceptual change. If students are not motivated enough to engage in reconstruction of their ideas then conceptual change cannot be possible (Palmer, 2003). In addition, the effect of CCTs are considered in the related questions and alternative conceptions, it can be said that the effect of CCTs is minor because of the conceptual change levels shown in Table 10. Contrarily, there are several studies suggesting that CCTs help students change their pre-existing conceptions or alternative conceptions to more scientific ones by producing dissatisfaction and presenting a correct explanation which is also understandable and plausible. In this study, because the learning environment was quite different from the one that the students were accustomed to, the students may not have paid great attention to the increased number of CCTs.
In the current study, according to Tables 8, 9 and 10, it was found that CCTs are slightly effective instruments for remedying alternative conceptions about solutions. This suggests that we may need to use more than one intervention model to effectively remedy the alternative conceptions in solution chemistry. In former studies concerning the effect of CCTs, CCTs were usually compared to traditional instruction (defined earlier in the introduction part). Therefore, CCTs were found to be highly effective, but in this study, in the control group's intervention, the REACT strategy was used and it was also effective at dealing with the alternative conceptions. So in this study the effectiveness of CCT was found to be minor. Also, to test the real effect of CCTs, it is suggested to implement a further study with one experiment group which will be taught using CCTs in the REACT strategy and one control group which will be taught using a traditional (i.e. chalk and talk) method.
Consequently, in this study it was found that the use of relevant contexts could help students to remedy alternative conceptions in solution chemistry. The REACT strategy effectively helped students to relate the content knowledge and the context which was related to the daily life. On the other hand, using CCT embedded within the REACT strategy did not provide a superior effect. It cannot be said that CCTs were not effective in remedying the alternative conceptions held for solution chemistry but their effect was found to be minor in this study. Because the REACT strategy made students highly motivated, students liked daily life materials and contexts, they could not focus on the CCTs as expected. The learning environment was quite different for the students; it may be that they focused on the different materials, so they did not pay attention to the presence of the CCTs.
According to Bodner (1990) the only way to deal with students' alternative conceptions is to convince them to construct a more plausible concept. Because of this, we have to show students that their alternative conceptions are not so powerful at solving problems. By doing this, we have to take into account their pre-existing knowledge. In this study, we considered students' existing conceptions and planned to deal with them by means of the REACT strategy and CCTs. So, for all of the chemistry topics, we should consider possible alternative conceptions if there is no time to explore them. Likewise Posner et al. (1982) suggested that there should be four conditions necessary for conceptual change: dissatisfaction with the existing knowledge, and that a new introduced concept should be intelligible, plausible and fruitful. This study may be helpful for diagnosing alternative conceptions and guiding researchers on how to remedy them. We modestly suggest that teachers and researchers should devise new pedagogies for conceptual change due to curriculum overload. Based on this study and previous studies, CCTs can be read in a couple of minutes and also they are cost and time efficient. Hence, CCTs could be designed and implemented in schools.
Sample questions of SCT | Sample questions of clinical interview |
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1. When Canan noticed the soup unsalted, she added some amount of salt and mixed it. Then, she tasted the soup and she felt the soup salted but she could not have seen the salt substances in the soup. The salt substances………because…………
11. A student took two beakers and she added in the same amount and same temperature of water (100 g) to the beakers. Then, she added 5 g of X salt to the first beaker, 80 g of Y salt to the second beaker. She started to mix the solutions with a glass stirrer and she noticed that there were salt substances undissolved in the bottom of the first beaker. Although she added more amount of salt to the second beaker, there were not salt substances in the bottom of the second beaker. According to you, what does she try to prove about solutions? Please explain. |
1. You add 100 g of water to two beakers and you put granulated sugar to the first beaker, and in the same amount of powdered sugar to the second beaker. What do you expect to happen in the solutions? Please explain.
12. How would you decide which substances dissolve and not dissolve in the solutions? Why? |
Step | Lecturer's role | Students' role |
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Note: this example outline is implemented in the experimental group as well, but in the control group, only CCT1 and CCT2 are not used, the rest of the outline is implemented as well. | ||
Relating | The teacher passed a reading text about solutions. In the text, there was a story of three friends in a cafeteria. The friends were talking about ordering some drinks such as milk and tea. Then one of the friends wanted to order a chocolate pudding. The teacher asked some curious questions to activate students' pre-existing knowledge by referring to the text, i.e. “What do you think about milk, mixture or solution?” “What do you think about that pudding is a solution?” “Where does sugar go when she adds it to her tea?” | The students carefully read the text and answered the questions using their pre-existing knowledge. Students tried to explain solution and dissolution process. They did not know how to explain and relate the pudding and the solutions. |
Experiencing |
She handed the CCT1 and CCT2 and gave time students to think about the question and write down the answer. CCT1 was focused on the dissolution process, whereas CCT2 was focused on the types of solution. After discussing the alternative conceptions mentioned in the CCT1 and CCT2, she guided students to observe the plausible and intelligible new knowledge by the hands-on activities.
She afforded the students to engage in hands-on activities such as “Are the solubility of solids similar in water and other liquids?” and “Are all liquids water soluble?” She tried to show students their knowledge's unfruitfulness by the activities. She promoted the students to present their knowledge of the solution chemistry and guided them whenever they needed. |
The students carefully read the questions in CCT1 and CCT2. They wrote down their thoughts about the questions and they read the scientific explanation given in CCT1 and CCT2. Students started to feel dissatisfaction about their existing knowledge.
The students carried out the hands-on activities such as “Are the solubility of solids similar in water and other liquids?” and “Are all liquids water soluble?” and filled in the experiment sheet based on their observations. After students understood that the new knowledge was more appropriate in explaining the questions, they eagerly accepted and understood the new knowledge. |
Applying | She promoted the students to present their knowledge of the solution chemistry and guided them whenever they needed. She showed some examples of explaining dissolution process by the projection on the board. She tried to clarify the dissolution on students' minds by different examples. | The students watch the examples projected to the board and interactively discussed all items with the lecturer. Hence, they transferred their gained knowledge to different issues. They understood that dissolution was related to the molecules' polarity or nonpolarity. |
Cooperating | She called the students for searching the question “What kind of mixtures are the jelly and cream existing in the desserts in the cafeteria? Why? What is the difference of these mixtures from solutions?” as a group work. She gave time to search the question and wanted them to prepare an answer as a group. | The students searched and responded the research questions within their small groups and presented their views within a whole-class discussion. Because it was important to be active in their own learning process and to get a peer teaching, they learned the research question better. |
Transferring | She passed a worksheet about the factors affecting solubility. Then she asked some questions to stimulate students' knowledge such as “Have you ever paid attention to that sugar disappears in hot water very quickly than in cold water? Which factor or factors can affect the solubility?” “How can temperature affect the solubility?” “after adding sugar to tea, if we stir the solution very quickly, does it affect the solubility?” | After taking the worksheet, students saw a question determining their knowledge about the factors affecting solubility. Students tried to answer by predicting, and then they performed the steps in the worksheet and discovered the factors affecting solubility by using daily life materials such as sugar, salt, chalk. Hence, they transferred their knowledge gained in previous steps to different parts of the topic. |
Footnote |
† This study was granted by Giresun University Scientific Research Projects Unit (GUBAP – Project No: EĞT-BAP-A220413-53). |
This journal is © The Royal Society of Chemistry 2015 |