understanding the alternative conceptions of pre ... - Springer Link

JUN-YOUNG OH

UNDERSTANDING THE ALTERNATIVE CONCEPTIONS OF PRE-SERVICE SECONDARY SCIENCE TEACHERS ABOUT TIDAL PHENOMENA BASED ON TOULMIN’S ARGUMENTATION Received: 26 January 2012; Accepted: 18 January 2013

ABSTRACT. Constructing explanations and participating in argumentative discourse are seen as essential practices of scientific inquiry. The objective of this study was to explore the elements and origins of pre-service secondary science teachers’ alternative conceptions of tidal phenomena based on the elements used in Toulmin’s Argument Model through qualitative research. The data were collected from three pre-service secondary school teachers (D.-K. University, Teachers’ Colleges, junior and senior) in the Republic of Korea using a variety of qualitative research methods. We present three pre-service teachers as examples of 20 pre-service teachers for determining each pre-service teacher whether the pattern of his/her responses to all of the questions investigating a given concept can be explained by the consistent use of components of argument. The results of this study showed “the model with the Earth’s center at rest” backing their warrants as an element of Toulmin’s Argument Model. As a result, science educators must explicitly address these presuppositions or implicit beliefs and must help the students form links between their everyday experiences and scientific knowledge. Therefore, educators must be aware of the influence of students’ presuppositions and must use acceptable scientific concepts (the center of mass of the Earth–Moon system) based on argumentation to guide their construction of scientific concepts. KEY WORDS: alternative conceptions, implicit backings, teachers, tidal phenomena, Toulmin’s Argument Model

INTRODUCTION Argumentation is important for developing explanations, models, and theories. Scientists use argumentation to relate evidence to claims through the use of warrants and backings (Toulmin, 1958). Learning science involves the construction and use of tools to generate knowledge about natural phenomena. From this perspective, argumentation is a significant tool that is instrumental to the growth of scientific knowledge (Schwarz, Neuman, Gil, & Ilya, 2003), espeElectronic supplementary material The online version of this article (doi:10.1007/s10763-0139403-2) contains supplementary material, which is available to authorized users.

International Journal of Science and Mathematics Education (2014) 12: 353Y370 # National Science Council, Taiwan 2013

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cially conceptual change (Feldman, 2000; Ford & Wargo, 2012). These approaches contrast the traditional perspectives on science learning that focus on problem solving (Gable & Bunce, 1984) and learning concepts (Cros, Chastrette, & Fayol, 1987). Tidal phenomena have been identified as some of the most difficult concepts in astronomy (Oh & Kim, 2006). According to current university physics textbooks (Benson, 1996, p. 277), the model with the Earth’s center at rest is clearly inadequate. If we include the Earth’s daily rotation, there would be one huge tide each day that would submerge many of the coastal areas. Thus, we first consider that the Earth’s center is fixed in space, and then we investigate how the Earth’s center being at rest has occurred. Therefore, we explored the elements and origins of pre-service secondary science teachers’ alternative conceptions of tidal phenomena based on the elements in Toulmin’s Argument Model (Toulmin, 1958).

BACKGROUND Argumentation in Science Education Toulmin (1958) has argued that arguments must be analyzed using a richer format than traditional formal logic, in which only premises and conclusions are distinguished. Toulmin’s argument can be defined as a set of claims about a set of data, the warrants used to justify these claims, and rebuttals to claims or warrants. The data consist of facts that support the claim. A warrant is an inference according to which the data support the claim, and the backing provides support for the warrant. A rebuttal provides conditions of exception for an argument, and a qualifier can express the degree of force that the data give to the claim by the warrant (Verheij, 2005). As shown in Fig. 1, because of the addition of a variety of backings, we will use a modification of Toulmin’s model in this research (Rieke & Sillars, 2005, p. 150). Educational research has realized both alternative explanatory models and worldview presuppositions that emerge from the Grounds

Claim

Backing

Backing Warrant Rebuttal Backing

Figure 1. Modified Toulmin’s argumentation model by Rieke & Sillars (2005)

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knowledge base from which incoming information is perceived and processed (Driver, Guesne, & Tiberghien, 1985). We argue that claims are defensible due to their backing. Thus, arguments that claims are consistently defensible by a backing are coherent. Therefore, there is a wealth of empirical work in conceptual change that speaks to the effectiveness of making students aware of their preconceptions through argumentation. Role of Interviews through Counterclaims for Rebuttals (Discrepant Questions and Discrepant Events) This research proposes to use these goals to understand students’ engagement with these practices and to design instructional interventions to support students. Thus, we use this counterclaim as a lens to investigate the question. Therefore, oppositional episodes for discrepant questions (rebuttals) or discrepant events by a counterclaim have the potential to modify the counterclaim. The questions were divided into major types: “supporting questions” and “discrepant questions.” Supporting questions were employed in the curriculum to activate students’ existing knowledge, relate this knowledge to experiences, and intrinsically motivate students (Rea-Ramirez & Núñez-Oviedo, 2008). The questions were not intended to produce dissonance but to assist students in generating ideas before and after the evaluation phase. Discrepant questions may stimulate students to engage in a cognitive process that is much more student-driven and interactive and that allows students to evaluate and modify or construct information in the form of a workable model. It is also important to distinguish discrepant questioning from discrepant events. Thompson (1989) states that a discrepant event occurs “when something a child expects to happen does not occur. The result is the opposite of what was expected, and it contracts the belief of the individual,” thus referring to an observed event. In contrast, discrepant questioning does not involve actual events or experiments but proposes an idea or concept (or possibly a thought experiment) that contrasts with a belief held by the student, generally in the form of an open-ended question (Rea-Ramirez & NúñezOviedo, 2008, pp. 198–199). Thus, we use “support questions” for the construction of the explanatory alternative models and “discrepant questions or discrepant events” for the modification of these alternative models. The Representations about Tides as a Title Section in Current University Physics Textbooks (Benson, 1996, p. 277) Earth’s Center of Rest Let us consider the Earth as a uniform sphere covered by a layer of water. Let us see what would happen if the Earth’s center were fixed in space. The

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ocean closer to the Moon would experience a larger gravitational pull than the ocean on the far side of the Earth. Because water can flow, this variation in the gravitational force across the dimensions of the Earth would cause the ocean to heap up “under” the Moon. If we include the Earth’s daily rotation, there would be one huge tide each day that would submerge many of the coastal areas. In fact, there are two tides per day, and they do not have such catastrophic effects. The model with the Earth’s center at rest is clearly inadequate (Benson, 1996, p. 277; Fig. 2). Earth and Moon Revolve About Their CM The Earth does not have infinite mass, so it does not remain fixed as the Moon orbits around it. (We are not interested in the Earth’s orbit around the Sun.) Both the Earth and the Moon revolve around their common CM. In fact, both are in free-fall. The CM is approximately 4,500 km from the center of the Earth. If we ignore the daily rotation, each point on the Earth describes a circle with a radius of 4,500 km each lunar month (27.3 days) (notice that each point moves in a circle with its own center; refer to Fig. 3). The force exerted by the Moon on a given particle at the surface of the Earth is directed along the line joining the Moon and the particle. The centrifugal force the particle exerts for its circular path is provided by the component of the gravitational force due to the Moon along the Earth–Moon line. The tidal force occurs due to the summation between

Figure 2. If the Earth’s center were at rest, there would be one huge tide each day (from Fig. 13.21 of Benson, 1996, p. 277)

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Figure 3. The dashed paths indicate that both the Earth and the Moon revolve around their common center of mass (from Fig. 13.22 of Benson, 1996, p. 277)

the gravitational force and centrifugal force. We have modified them as shown in Fig. 3 (Benson, 1996, p. 277). Research Questions Pre-service teachers tend to project the behaviors of their instructors in colleges in class teaching after they become teachers (Lortie, 2002, pp. 61–67; Lee, 2012, p. 84). Therefore, there is a need to explore the formation of the concept of pre-service teachers. However, the causes of tidal motion are excluded as a topic in elementary curriculums in South Korea. Thus, in this paper, the participants are preservice secondary teachers rather than pre-service elementary teachers. The objective of this study was to explore the elements and origins of preservice secondary science teachers’ alternative conceptions of tidal phenomena based on the elements used in Toulmin’s Argument Model through a variety of causal questions, figure representations, and model operations. Thus, the following research questions formed the basis of this study: 1. What are the causal claims of pre-service secondary school teachers about alternative models of tidal phenomena that are expressed as their dominant conceptions in clinical interviews? 2. What are the possible sources of these initial claims about alternative conceptions, using warrants to support the initial claims of figure representations and supporting these warrants with model operations?

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3. How sound are teachers’ intuitive (or informal) knowledge (warrants), in general, and their argumentation strategies, in particular? 4. What are the educational implications of conceptual variations in tidal phenomena for pre-service teachers? METHODS General Overview Lythcott & Duschl (1990) outlined principles that should be considered in interview design. The first principle is “to probe the same topic of knowledge among the children to determine their dominant conceptions and/or misconceptions.” The second principle is to determine the origins of these conceptions/misconceptions. According to these principles, the first phase of the interview should investigate the formation of students’ claims through verbal interviews. After identifying these claims, the second phase involves the principles of warrants that legitimize claims with figure representations. The third phase explores the backings that support the warrants with model operations. The clinical method does not simply ask children questions verbally that could just as well be asked with written questioning. Instead, it induces students to represent a picture and model using their own language about the world. That is, this method allows students to talk of their own accord. Contexts Based on Toulmin’s analysis, Lythcott & Duschl (1990) suggested that a sound argument shows how conclusions are drawn from the data via warrants that are supported by acceptable backings. Students’ verbiage from interviews is compared to public domain science knowledge. Thus, verbiage that can be seen as consistent in meaning with public domain science knowledge can be said to arise from students’ scientific conceptions. Verbiage that is inconsistent with public domain science knowledge can be said to arise from non-scientific conceptions. The claims may be defensible because of illegitimate warrants on account of non-scientific conceptions and naive theory. Participants The participants in this qualitative research were three volunteers chosen from 20 pre-service secondary science teachers in a teachers’ college at 0.-0. University. We present three pre-service teachers as examples of the 20 pre-service teachers to determine for each one whether the pattern of their responses to

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all of the questions investigating a given concept can be explained by the consistent use of components of argument. These participants were sampled and surveyed to investigate their explanatory frameworks for tidal phenomena. The participants were senior (S1, S2, S2) teacher’s college students. We used a variety of interview methods. All classes were taught by a male science professor with 20 years of teaching experience, who was assisted by a male teaching assistant in science with 10 years of teaching experience at K.-S. Girls’ High School. The professor held a Bachelor’s of Science degree and a Master’s of Science degree in astronomy, as well as a doctoral degree in science education and the philosophy of science. Instruction In this study, all of the analysis process is shown in Fig. 4, and all of the research process is shown in Fig. 5. Preliminary Phase. Using a written activity sheet, all pre-service teachers were asked to reflect on their explanations of tidal phenomena, that is, their dominant conceptions. Standards were established to code the interview material based on the frequency of occurrences. For the content configuration, the participants were asked to write their answers on a written activity sheet in accordance with the content of the interview. As the individual interviews proceeded, the contents were confirmed and amended. Data Source and Data Analysis To assess possible conceptions, the participants were asked, “Why did these tidal phenomena happen?” To assess dominant conceptions, the participants were asked, “Which is the most influential one among them?” Selected Items from Written Activity Sheets Below is an example taken from the questions that lead to dominant concepts. Preliminary phase: 1. For possible conceptions, "Why did these tidal phenomena happen?”

_____________________________________________________________________________

2. For dominant conceptions, "Which is the most influential one among them? "

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Claims:

Known tidal phenomena evidence

“Why did these tidal phenomena occur?” 1.

Moon’s attraction

2.

Third Phase: Backing: New evidence

Sun’s attraction

3. Third celestial body 4. Earth’s rotational

1. Cubic tidal model

centrifugal force

2. Disk-shaped model 3. The figures in text

5. Earth's revolving centrifugal force

Second Phase: Warrants: New principles through combination of claims

How can they link and order conceptions consisting of a claim through figure representations (excluding unclear representations) ? Third Phase: Backing : the entrenched supposition

What does it mean that the Earth is more massive than the Moon? Based on Operation action by model building 1.

The fixed center of the relative mass of the Earth

2.

From the fixed center of the relative mass of the Earth to the center of mass of the

Earth’s center orbital motion

3. The center of mass of the Earth’s center orbital motion Fourth Phase: The soundness of the argument based on the backing

Whether the argument is sound based on the backing based on Benson (1996) 1.

Scientific concept (the center of mass of the Earth’s center orbital motion)

2.

Unscientific concept (the fixed center of relative mass of the Earth)

3.

Transitional concept

Figure 4. Criteria to classify each argumentation component

First Phase: Constructions of a Claim What are the causal claims of pre-service secondary school teachers for alternative conceptions of tidal phenomena, as presented in their dominant conceptions (first phase) in clinical interviews? After 1 week, the researchers (a science professor and a teaching assistant) explored the claims used to support the data, which consisted of some of the conceptions in the clinical verbal interviews.

ALTERNATIVE CONCEPTIONS ABOUT TIDAL PHENOMENA One week Preliminary Phase:

One week

One week

First Phase:

Second Phase:

Dominant

Seed-claim

representation

conceptions

(5~10min.)

(15~20min.)



Through figure

through writing

Modified

Argument for



all members

(5-15min.)

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Confirming

the main components of the arguments produced

Third Phase:

Fourth Phase:

Through model

Soundness of

operation

the backings

(15~20min.)



Evaluation by their arguments

using criteria of soundness

Figure 5. The procedure for the analyzed phases of the interview data

The first set of questions was intended to assess the participants’ initial conceptions. For possible conceptions, the participants were asked, “Why did these tidal phenomena happen?” For dominant conceptions, the participants were asked, “Which is the most influential one among them?” First, these seed-claims (beginning claims) were surveyed. Each claim was investigated for 5∼10 min by the professor and the teaching assistant. Then, the seed-claims that were defensible to counterclaims were modified to claims: “Don’t you think that it exerts this pull on the far side of the Earth that is facing the Moon?” (Counterclaim by discrepant events and discrepant questions). These counterclaims were investigated for 5∼15 min by the professor and the teaching assistant. The researchers waited patiently until the participants restrained, changed, or withdrew their initial claims to refute their claims with discrepant events and questions. The student samples were investigated to code the main components of the arguments produced. Each argument component was selected as follows. The participants’ dominant conceptions consisted of two types of conceptions (seed-claim and modified claim). What are the origins of the mental models that use warrants to support the first claim among their figure representations (second phase) and back up these warrants through model operations (third phase)?

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Second Phase: Exploration of the Warrants through Figure Representations The second set of questions was directed at legitimated warrants (e.g. reasoning or principles) to link the data to support claims through figure representations. “How can the participants link and order conceptions consisting of a claim through figure representations?” The figure representations were used only to connect data and claims using concepts, so these figure representations were excluded from the backing data. As identified in the verbal responses and the accompanying diagram, the participants were asked, “Please draw a figure representation of tidal phenomena.” They were also asked, “What are the sources of these attracting forces that produce the bulges on the far side of the Earth facing the Moon, as shown in your representation?” and “Which part is more bulging?” After 1 week of the first phase of investigation, the participants were interviewed for 15∼20 min by a professor and a teaching assistant. The student samples were investigated to code the arguments. Each argument component was selected in the first phase conceptions. Third Phase: The Backing for the Warrants through Model Operations The third set of questions was aimed at the new evidence and the backing data for model operations as well as the empirical origins of backing warrants. We explore the backing (e.g. worldview and implicit knowledge) for the warrant through model operations. After 1 week of the second phase of the investigation, the participants were interviewed for 15∼20 min by a professor and a teaching assistant. They were asked “What does it mean that the Earth is more massive than the Moon?” based on the operation action of model building. The student samples were investigated to code the arguments produced. Fourth Phase: The Constructions and Appraisal of the Soundness of Toulmin’s Argument Model Based on Backing This phase examined the soundness of an argument based on its backing. We analyzed the elements of Toulmin’s argument for explanation frameworks in a variety of ways. Specifically, we appraised and classified the participants’ arguments in terms of their soundness based on the explored backings (Oh & Kim, 2009), whether they used scientific (the center of mass of the Earth’s center orbital motion) or unscientific concepts (the fixed center of the relative mass of the Earth; based on Benson 1996). Toulmin’s model is an effort to present formal logic in everyday language. Comparing Toulmin’s model with formal logic, we can see that

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claims correspond to the conclusions of formal logic. Data and evidence are minor premises, and reason serves as a major premise. The validity of the entire demonstration is assessed by close consistency with the data and claims through warrants. The sound demonstration shows that claims proceed from data to warrants supported by backing. If the data are correct and the warrant is legitimate, we must accept the interpretations that emerge from the study (Oh & Kim, 2009). RESULTS AND DISCUSSION Results and Findings First Phase: Constructions of a Claim Through Causal Verbal Interviews Based on Discrepant Events or Discrepant Questions. S1, S2, and S3 were all the same seed-claim, but the claims differed. The seed-claim was that the students explained tidal phenomena as created by the Moon’s attraction on the Earth’s ocean to support the initial data. S1: After a researcher offered new evidence, such as a counterclaim (discrepant events) that differed from the seed-claim in addition to the conception of the centrifugal force caused by the Earth’s rotation, the student modified her claims. S2: After a researcher offered new evidence (such as a counterclaim that differed from the seed-claim) in addition to the concept of the gravitational forces caused by the Sun’s pull being more than the centrifugal forces caused by the Moon’s rotation, the student modified her seed-claims. S3: In addition to the concept of centrifugal forces caused by the Earth’s revolution around the Sun or by the Earth’s revolution around a common center of mass and including the centrifugal forces caused by the Earth’s rotation, the student implicitly modified her parent claims (for S1, S2, and S3 interview data, refer to Electronic Supplementary Material). Second Phase: Exploration of the Warrants Through Figure Representations. S1: In the second phase, the students’ responses were analyzed. S1: Warrants are the rules of reasoning. They consist of the Moon’s gravitational attractions and the Earth’s rotation. The Earth’s rotation causes centrifugal forces. These forces cause tidal phenomena. The student uses warrants to legitimize her claims. S1 offers the figure representations as defenses for their claims (for S1 interview data, refer to Electronic Supplementary Material). In Fig. 6, first, the part that is closer to the Moon is attracted by the gravitation of the Moon (the figure surrounding the Earth). However, the part which is further from the Moon is added to by the

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moon’s attraction

Earth’s rotation centrifugal force

Figure 6. Representation of a figure drawn by S1

centrifugal force due to rotation of the Earth (the part which is further from the Moon is added). S2: The student’s warrants and line of reasoning consisted of the Moon’s gravitational attraction on the Earth in addition to a celestial body’s forces (perhaps) regarding tidal phenomenon to legitimize her claims, offering the figure representations as defenses for these claims (for S2 interview data, refer to Electronic Supplementary Material). In Fig. 7, at first, the part which is closer to the Moon is attracted (the additional part which is closer to the Moon). Nevertheless, the third celestial body exerts a pull on the opposite part (the entire part expressed by the question mark). S3: Warrants consisted of the Moon’s gravitational attractions in addition to the conception of the centrifugal forces caused by the Earth’s revolution around the Sun, or caused by the Earth’s revolution around their common center of mass to legitimize her claims, offering the figure representations to implicitly defend her initial claims (supporting questions; for S3 interview data, refer to Electronic Supplementary Material). Third body’s moon’s

attraction

attraction Earth Moon Third celestial body

Figure 7. Representation of a figure drawn by S2

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In Fig. 8, at first, the part that is closer to the Moon is attracted. However, the Sun simultaneously attracts the opposite part (the part which is further from the Moon). Third Phase: the Backing for the Warrants Through Operating Actions Using Model Building. S1: To back up the student’s rotation claims, the student must make a disk model. This model emerged from the results of the student’s disk tidal model (see Fig. S1 in Electronic Supplement Material) and the text’s plane-type figures. The results indicated that the student is constrained by entrenched presumptions. The fixed center of the Earth was indicated at the Earth’s center of rest, which caused the Earth to be more massive than the Moon (for S1 interview data, refer to Electronic Supplementary Material). S2: To support the third celestial body claim, the student must create a 3D model and provide new evidence. This model representation emerges from the results of the student’s 3D tidal model (see Fig. S2 in Electronic Supplement Material) because the student did not include the effects of the Earth’s rotation (for S2 interview data, refer to Electronic Supplementary Material). These results indicated that the student was constrained by entrenched presumptions, including the fixed center of the Earth as indicated at the Earth’s center of rest, caused by the fact that the Earth is more massive than the Moon, to back one of their warrants. S3: To back up the warrants of the Earth’s centrifugal force and its movement around the Sun or its center of mass, the student must make a 3D model using new evidence. This model representation emerges from the results of the student’s disk-type tidal model (see Fig. 3 in Electronic Supplement Material; for S3 interview data, refer to Electronic Supplement Material). These results indicated that there are transitional stages from entrenched presumptions to the concept of the fixed center of the Earth,

Moon’s attraction Sun

Earth

Sun’s attraction

Figure 8. Representation of a figure drawn by S3

Moon

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as indicated by the Earth’s center of rest (Benson, 1996, p. 277) because the Earth is more massive than the Moon. Fourth Phase: the Construction and Appraisal of the Validity and Soundness of Toulmin’s Argument Model Based on Backing. S1 and S2: The seed-claims used by the students explained the tidal phenomenon only by the Moon’s attraction on the Earth’s oceans to support the initial data. S1 modified her seed-claims by adding the concept of the centrifugal force caused by the Earth’s rotation as a defense against new evidence (two occurrences per day). S2 modified her seed-claims by adding the concept of celestial body forces as a defense against new evidence (two occurrences per day and far-side bulges). Table 1 presents the structure of students’ alternative conceptions based on the structure of Toulmin’s argument (for Table S1, refer to Electronic Supplement Material). As shown in the Electronic Supplement Material (Table S1), there are specific explanations for tidal phenomena, such as the fixed center of the Earth and the Moon’s orbit around the fixed planet Earth (S1 and S2). This explanation is embedded within the aforementioned explanatory framework because the Earth is considered a physical object (as opposed to an astronomical object). Thus, the Earth is constrained by all the presuppositions that apply to physical objects. These presuppositions (of a fixed planet TABLE 1 Classifications and structure of alternative conceptions of pre-service science secondary teachers based on backings for tidal phenomena Claim Patterns based on backing

Backing

Alternative conceptions S1 Fixed center of of non-scientific backing the Earth (nonNewtonian) Alternative conceptions S2 Fixed center of of non-scientific backing the Earth (nonNewtonian) Alternative conceptions S3 Fixed center of of transitional backing the Earth⇒ orbiting center of the Earth × Orbiting center Possible scientific of the Earth concepts of scientific (Newtonian) backing

Seed-claim

Claim

Warrant

Moon’s pull Earth’s on the ocean rotation

On accounts of nonNewtonian Moon’s pull The third On accounts on the ocean celestial of nonNewtonian body Moon’s pull (?) Accounts of mixed backing

Moon’s gravitational attraction on the Earth

Accounts of Newtonian theory

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Backings: New evidence: Disk-shaped tidal model operation representations caused by the Earth’s rotation centrifugal force and the figures in text Rebuttals: Unless the Earth is more massive than the Moon Evidence: Anyone who has spent even a few hours by the sea knows that the ocean’s level rises and falls during the day

Qualifiers: Presumably

Defended

Claims: This regular change is caused mainly by the Moon’s and the Earth’s rotation

Warrants: The Moon exerts a gravitational attraction and the Earth’s rotation exerts centrifugal force on the earth’s oceans On account of … Backing: The entrenched supposition The Moon (the Earth’s satellite) orbiting around a more massive Earth than Moon results in the fixed center of the relatively massive Earth and earth’s rotation axis spins like other planets

Figure 9. The elements of alternative conceptions of pre-service secondary science teachers (S1) adapted to Toulmin’s Argument Model (1958) argument model and based on Benson (1996) for tidal phenomena patterns

Earth) can impede a student’s understanding of the sphere shape of the Earth caused by the Earth’s rotation on its axis. These concepts are necessary to understand students’ initial explanations of the tidal cycle. Finally, we represented and interpreted the structure of pre-service teachers’ explanatory frameworks of tidal phenomena in an adapted Toulmin’s Argument Model. The pre-service secondary science teachers formed nonscientific backings, and the remaining students formed transitional backings to explain tidal phenomena. These explanations seem to be based on nonscientific backings and do not show an influence from the accepted scientific backing of tidal phenomena explanations. Figure 9 shows that these results (S1) involve the elements of Toulmin’s Argument Model (Toulmin, 1958). CONCLUSIONS AND IMPLICATIONS We have attempted to explore Toulmin’s four elements of the argument, data, claims, warrants, and backings, in some detail with respect to qualitative research on the alternative conceptions of tidal phenomena of pre-service secondary science teachers.

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First, what are the causal claims of pre-service secondary school teachers regarding their alternative conceptions explanations of tidal phenomena? The first field probed the claims of pre-service secondary science teachers to determine their dominant conceptions and/or misconceptions for their alternative conceptions. Their networks of claims consisted of the Moon’s attraction in addition to the Earth’s rotational centrifugal forces. Second, what are the origins of alternative conceptions’ warrants to support the initial claims through their figure representations and for backing up these warrants through model operations? The second set of questions was aimed at legitimizing warrants (e.g. reasoning and principles) to support claims through figure representations. How can the participants link and order conceptions consisting of a claim through figure representations? The second field involved the criteria by which the believability of a qualitative narrative is determined and considered the coherence or tightness of the argument presented. Thus, in this research, we encouraged the students to defend their claims by legitimate warrant on accounts with coherent backing using a variety of evidence from the adapted Toulmin’s model. The third set of questions was aimed at the new evidence in model operations and its empirical origins in backing warrants. We explored the backings (e.g. worldviews and implicit knowledge) supporting the warrant through model operations. We argue that these coherent backings are the origins of the students’ initial alternative conceptions. Thus, it is an important conclusion that their claims can be defensible as students’ unstable centrifugal force on account of nonscientific backings (the model with the Earth’s center at rest), rather than acceptable view of shared meaning (the center of mass of the Earth–Moon system). Thus, pre-service secondary school teachers’ implicit use of the model with the Earth’s center at rest is consistent with the content of current university physics textbooks (Benson, 1996). Third, the fourth set of questions considered the soundness of the argument based on the backing for the warrants and the implicit meanings of the backing. Because the explanations seem to be based on non-scientific backings and do not show any influence from the accepted scientific backing of the tidal phenomena explanations, we called this model the “non-scientific backing explanatory framework.” The students in our sample were likely to form these explanatory frameworks with aspects of non-scientific backing and the “transitional explanatory framework,” which transfers from the non-scientific backing explanatory framework to the accepted scientific backing explanatory framework.

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Finally, what are the teaching strategies for conceptual changes? What are the implications for pre-service teachers? We believe that strategies must be developed to help students understand the center of mass of the Earth–Moon system. In fact, the Earth does not have infinite mass, and it does not remain fixed as the Moon orbits it. We can explicitly persuade students away from these beliefs and help students to restructure scientific concepts by doubting their claims and offering counterclaim evidence, such as the explanation of identical bulges on both sides of the Earth rather than large bulges on the side of the Earth near the Moon that was offered by the students as support for the initial data. We propose that the text’s figures must be changed from the flat type of tidal representations to cubic tidal representations because of the alternative conceptions caused by nonscientific entrenched presuppositions. ACKNOWLEDGMENTS This research has benefited enormously from input from several individuals. In particular I would like to thank Teacher Chi Bok Won at the Gyeong Seong Girls’ High School, for data collecting and analysis.

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