readiness to change the conception that “motion-implies-force”: a comparison of 12-year-old and...

LEARNING

Peter W. Hewson, Section Editor

Readiness to Change the Conception That “Motion-Implies-Force”:A Comparison of 12-Year-Old and 16-Year-Old Students

DAVID H. PALMERFaculty of Education, The University of Newcastle, NSW, 2308, Australia

ROSS B. FLANAGANFaculty of Science and Mathematics, The University of Newcastle, NSW, 2308, Australia

Received 19 December 1995; revised 29 May 1996; accepted 1 July 1996

ABSTRACT: Several investigators have reported difficulties in changing the alternative con-ceptions which high school students hold about aspects of mechanics. It has been suggestedthat students should be introduced to mechanics at a younger age because as they get olderthey become less willing or less able to change their ideas. To test this proposal, the presentstudy was designed to find out whether older students were less ready to change their concep-tions than younger students. Individual interviews were carried out with 63 students in year 6(ages 11–12) and 66 students in year 10 (ages 15–16). Those students who held the alterna-tive conception that “motion-implies-force” were asked to read a refutational text. This textwas “student-centered” in that it was not presented as the correct answer, but rather as just an-other possible alternative which the student could consider. Immediate and delayed posttests,and the metacognitive responses of the students, showed that conceptual change had occurredin 35% of the year 6 group and 44% of the year 10 group who had read the text (although thedifference in percentages was not significant). Therefore, there was no evidence to suggest thatconceptual change is more difficult for older students. © 1997 John Wiley & Sons, Inc. Sci Ed81:317–331, 1997.

© 1997 John Wiley & Sons, Inc. CCC 0036-8326/97/030317-15

Correspondence to: D. H. Palmer

INTRODUCTION

Over the last two decades a great amount of educational research has focused on the ideaswhich students have in relation to scientific concepts. It is now well established that, duringtheir experiences in everyday life, children develop their own ideas that they use to makesense of the natural phenomena they experience in the world around them, but in many casesthese ideas are quite different from the accepted scientific viewpoints. To the science educator,these ideas, or “alternative conceptions” (Gilbert & Watts, 1983) are important because theysignificantly interfere with learning (Pines & West, 1986).

One alternative conception that has been intensively studied is the Aristotelian idea that acontinuous action of a force is necessary to keep an object in motion. Although it represents away of thinking that has long been rejected by the scientific community, it has now been estab-lished that this idea often predominates among students. For example, Watts and Zylbersztajn(1981) found that 85% of students aged 14 years associated force with motion; and Sadanandand Kess (1990) found that 82% of their senior high school students indicated that a force is re-quired to maintain motion.

Furthermore, it appears that students hold onto this idea tenaciously. Clement (1982) foundthat 75% of a group of university students still indicated a force in the direction of the motionafter one semester of instruction in mechanics. Even courses specifically designed to changethis conception may have limited success: Thijs (1992), working with secondary students,found only a 10% improvement in scores after 5 weeks of instruction, and concluded that “thecourse is not successful in remedying the impetus idea, that is, simply associating force andmotion” (p. 166). Similarly, Gunstone, Champagne, and Klopfer (1981) found, after an 8-weekcourse designed to change their students’ alternative conceptions about force and motion, that“most students had not abandoned an Aristotelian view” (p. 31).

As this alternative conception is so resistant to change, it represents a major challenge toscience educators. However, given the “crowded curriculum” with which many teachers arefaced, particularly at the secondary level, it is unlikely that most would be in a position to de-vote a large amount of time to changing any one particular alternative conception that theirstudents may hold—even one as prevalent as the one described. One possible solution to thisproblem is to teach the students mechanics at a younger age. It could be reasoned, for exam-ple, that younger students have formed their conceptions more recently, and are thereforelikely to be more easily influenced by input from the teacher. Osborne and Wittrock (1983)stated that:

it appears that the age at which the restructuring occurs may be critical. If ideas are introducedat too young an age, problems can arise because of the pupils’ limited intellectual develop-ment. On the other hand, if children are left to accrete ideas to their existing knowledge struc-tures the difficulty of restructuring that knowledge is increased; pupils may become unwillingor unable to change their ideas. The logical consequences of these ideas may be a complete re-structuring or reordering of curriculum topics, e.g., teaching the ideas of momentum at age 11rather than age 16. (p. 504)

Cosgrove and Forret (1992) used the term “loss of plasticity” to describe this phenomenon:

we think that learners ought to be introduced at an early age to many topics that are tradition-ally left until much later, otherwise these topics might become impenetrable. This is calledloss of plasticity. . . . In the past curriculum planners have moved certain topics to later pro-grams because of the degree of difficulty teachers reported. What we are suggesting is that, forsome topics, such as electricity, the difficulty in mastering them is compounded by their lateplacement . . . (p.49)

318 PALMER AND FLANAGAN

Several authors have commented that students younger than 12 years are capable of learn-ing topics such as electricity (Cosgrove & Forret, 1992) and motion (Eckstein & Shemesh,1989; Osborne & Schollum, 1981), and that these children are interested and enthusiasticabout doing so. However, there is a lack of direct evidence as to whether or not conceptualchange strategies are in fact more successful with younger students. Studies that have exam-ined age-related science concept learning have focused mainly on: (a) descriptions of the con-ceptions students hold about specific science concepts (e.g., Driver, Leach, Scott, &Wood-Robinson, 1994); or (b) the effect of normal classroom instruction upon learning (e.g.,Novak & Musonda, 1991). On the other hand, studies of the effectiveness of specific concep-tual change techniques have mainly been aimed at a relatively narrow educational or age level(e.g., Thijs, 1992; Weller, 1995).

However, the following studies have provided some data about the effectiveness of conceptualchange strategies with students of different ages, although in neither study was it the primary re-search focus. Osborne and Black (1993), investigated the understandings of light held by childrenaged 7–11 and attempted to change their ideas to a more scientific model. One finding was thatthe intervention was slightly more successful among the older range of students. Dupin andJohsua (1989) found that an analogy about electricity in circuits was more successful in changingthe conceptions of eighth-grade students than sixth-grade students, although the eighth gradersdid receive slightly more instruction. Thus, there is some evidence to suggest that conceptualchange techniques may in fact be more successful with older students.

The extent to which loss of plasticity does actually occur is therefore problematic. The purposeof the present study is to test the proposition that conceptual change is more difficult for older stu-dents. This study compares the effectiveness of a specific conceptual change strategy, for the al-ternative conception that “motion-implies-force,” when used with students of different ages.

METHODOLOGY

The Sample

Individual, audiotaped interviews were carried out with two groups of students. The firstgroup consisted of 63 year 6 (age 11–12 years) students who came from four primary (i.e.,elementary) schools in southeastern Australia. The class teachers were asked to select studentswho represented a range of achievement levels within each class. The second group consistedof 66 year 10 (age 15–16 years) students who came from five secondary schools in the samearea as the primary schools. In each secondary school, the year 10 students came from classesthat were streamed according to their achievement in science— one third (approximately) ofthe students interviewed came from classes streamed as upper ability, one third from middleability classes, and one third from lower ability classes. The genders were roughly equallyrepresented in both primary and secondary groups.

The Instruments

The interviews consisted of up to four possible phases: pretest; intervention; immediateposttest; and delayed posttest. The interview procedure and the materials used during the in-tervention phase were developed and trialed during pilot interviews with 25 year 6 studentsand 11 year 10 students. These students were not included in the final sample.

Test Items. In the pre-/posttesting phases, an “interview-about-instances” (Osborne &Freyberg, 1985) technique was used. Five instances were used to identify students’

READINESS FOR CONCEPTUAL CHANGE 319

understandings of the forces acting on an object in motion. Each was presented with astick figure diagram and a short written description of the situation represented in the di-agram. The instances were similar in that they all represented everyday examples of ob-jects in linear or trajectory motion: instance 1 involved a tennis ball that had beenthrown vertically upward; instance 2 involved a person moving vertically upward from adiving board; instance 3 involved a tennis ball that had been thrown vertically down-ward; instance 4 involved a golf ball in trajectory motion; and instance 5 involved a ten-nis ball that had been bounced off the ground and was moving vertically upward.

Several studies have indicated that students’ responses to questions in mechanics will varyaccording to contextual features such as the type of moving body (Fischbein, Stavy, & Ma-Naim, 1989; Whitelock, 1991) or the direction of the motion (Clement, 1982). Conse-quently, the instances were designed so that they differed according to the nature of the mov-ing object (a ball or a person) and the direction of the motion (vertically upward, verticallydownward, trajectory). Although it is well known that students’ conceptions of force can beinfluenced by a range of other contexts such as the type of motion or the difficulty of theproblem (Finegold & Gorsky, 1991; Galili & Bar, 1992) it was not the intention in the presentstudy to investigate the effect of conceptual change techniques on each of these. Therefore, itwas decided to restrict the range of contexts and the difficulty level to the relatively small butclearly defined set as described above.

Instance 1 (a tennis ball being thrown vertically upward) formed the basis of the pretest.It was adapted from a well-known item used by Osborne and Schollum (1981). Instance 1was also presented in the intervention phase and in each of the posttests, and was intendedto be used as a direct measure of understanding, which eliminated any possible effect dueto differences in context. Each of the posttests also contained, in addition to instance 1,two other instances that were new to the students, and which were included to assess theextent to which the students’ conceptions were generalized to other, related contexts (i.e.,application).

Intervention Items. In the intervention phase, the students were asked to read a refuta-tional text (i.e., a short, written passage which directly refuted the alternative concep-tion). It was initially decided to use a text, rather than another method such asdemonstration or video, as a means of presenting the information because it offered avery convenient way to reduce the variability of the input of information given to eachstudent. Refutational texts have been shown to be effective with both elementary studentsand secondary students, and to result in long-term learning (Guzzetti, Snyder, Glass, &Gamas, 1993).

The text consisted of handwritten responses to the same questions asked during thepretesting phase (see below), as well as handwritten responses to two similar situations:a basketball in trajectory motion, and a person moving vertically upward from a trampo-line (Fig. 1). It is important to point out that the text was only intended to eliminate thealternative conception that motion-implies-force — it did not attempt to replace it withan understanding of Newton’s laws or to address any other conceptual difficulties (e.g.,with regard to gravity or friction). The text was examined by the teachers in each of theprimary schools and judged to be well within the readability levels of their year 6classes.

An important feature of this text was that it was “student-centered”—it was not presentedas the correct answer but rather as simply another option that the student could consider. Theinterviewer explained to each student that these were responses from “another student just


like you,” and in no way implied that they were correct or incorrect. The following is a repre-sentative transcription of what the interviewer said as the text sheets were handed to the stu-dent:

Now what I’ve got here is—there was another student just like you, but at another school. Iasked that person exactly the same questions, and got an answer like this. Could you just readwhat it says?

This approach was used so that less coercion would be involved than if the material had beenpresented as the correct answer. It was intended to allow the students an opportunity for a bal-anced reflection of ideas so they would be less likely to give rote answers which did not re-flect their true understandings. The students’ comments and responses during the pilotinterviews indicated that this strategy was likely to be successful.


Figure 1. The refutational text.

Procedure

All interviews were carried out by the same person.

Pretesting Phase. This stage was designed to identify those students who held the alterna-tive conception that motion-implies-force. As an introduction to the interview, and to helpthem become focused, the students were first asked for their understandings of the term“force” as it applies to science. They were then asked to describe their understanding of whatwas happening in instance 1, and to describe the forces (if any) which would be present on theball after it had left the person’s hand, while it was still moving upward. Subsequently, thosestudents who had not described a force in the same direction as the motion were thanked andreturned to class, their interviews terminated at this point.

Intervention Phase. Those students who did describe a force in the same direction as themotion were then presented with the student-centered refutational text. The students weregiven as much time as they wanted to read the text. To check their comprehension each stu-dent was asked to briefly describe the main point the text was making about instance 1 (Item 2in the text).

Immediate Posttest. This phase was intended to identify those students who had revisedtheir conceptions as a result of reading the text. Immediately after the students had finishedreading the text it was removed and they were presented with a new worksheet showing in-stances 1, 2, and 3. The order of presentation of the three items on the sheet was systemati-cally changed. For each instance, after discussion of what was happening in the diagram, thestudents were asked to describe the forces (if any) that would be present on the moving ob-ject, and to draw them on the diagram. The interviewer made no mention of the text at thisstage (i.e., the interviewer did not instruct the students to consider the text while answering).The students were then asked to comment on their responses and the responses of “the otherstudent” (i.e., the refutational text).

Delayed Posttest. Those students who had indicated in the immediate posttest that they hadrevised their conception of a “motion–force,” participated in follow-up interviews 1–2 weekslater (the times varied due to student availability and school science timetables). Each studentwas presented with a sheet showing instances 1, 4, and 5. The order of the items was system-atically changed. For each instance, after discussion of what was happening in the diagram,the student was asked to describe the forces (if any) that would be present on the moving ob-ject and to draw them on the diagram.

RESULTS

The students’ responses were categorized according to the presence or absence of a force inthe same direction as the motion. The two investigators independently categorized the re-sponses of each student for each instance and agreement was reached in over 99% of cases.Those responses that were vague or upon which the two investigators did not agree were con-sidered inconclusive.


Pretest

Students who made any inconclusive responses (two from year 6 and three from year 10)were identified and their data were not included in any further analyses. The results describednext are based on the remaining 61 year 6 students and 63 year 10 students. Sixty-six percentof the year 6 students and 75% of the year 10 students described a force in the same directionas the motion in instance 1 and were therefore considered to hold the alternative conception.Both groups of students used very similar words to describe what the force was doing andwhere it came from. Students generally considered that the force was pushing the ball upwardand that it came from the person.

Immediate Posttest

Forty year 6 students and 47 year 10 students participated in the intervention phase and theimmediate posttest. The immediate posttest revealed that 43% of these year 6 students and57% of year 10 students had revised their conceptions. Students were considered to have re-vised their conceptions if they demonstrated both understanding (i.e., no motion–force in in-stance 1) and application (i.e., no motion–force in at least one of the other instances). Themajority (76% of the year 6 students and 89% of the year 10 students) responded consistentlyto all three instances. A x2 test showed no significant difference between genders with regardto conceptual change for either year 6 (x2 5 0.406, df 5 1, N 5 40, p . .05) or year 10(x2 5 1.320, df 5 1, N 5 47, p . .05). Among the year 10 students conceptual change was notinfluenced by achievement level (x2 5 0.716, df 5 2, N 5 47, p . .05).

Delayed Posttest

Responses in the delayed posttest revealed that 35% of the year 6 students and 44% of theyear 10 students who had read the text had revised their conceptions. A x2 test showed that thedifference between year 6 and year 10 was not significant (x2 5 0.787, df 5 1, N 5 85,p . .05). These percentages were lower than in the immediate posttest, indicating that somestudents had reverted back to a motion–force conception.

Students’ Comments about Their Responses

Students Who Revised Their Conceptions. Those students who indicated in the immedi-ate posttest that they had revised their conceptions were questioned on their reflections aboutthe process. Although some of them were not able to clearly describe their thoughts at length,these students did confirm that they had changed their minds about the presence of amotion–force in these instances. Nearly all of these students referred to the text as influenc-ing their change of mind (although two year 6 students and one year 10 student did not statethat they were influenced by the text). When questioned about which actual part of the texthad influenced them the most, the largest proportion (45% overall—the year 6 students re-sponded in a very similar way to the year 10 students, so the numbers have been combined) ofthese students simply referred to the statement that the hand is not pushing the ball any more.For example, the following interview transcript was recorded with a year 6 student (I 5 inter-viewer, S 5 student):

I: Have you changed your mind about that situation?

S: Yeah. The ball has actually left the person’s hand so there is no more force.


I: So what made you change your mind about that?

S: They wrote “the hand’s not pushing the ball any more.” There’s no more force when it’s lefthis hand the only force is gravity . . .

I: And why did that make you change your mind?

S: Because of the way I thought about it.

A much smaller proportion (16%) of students specifically referred to the analogy of the handpushing the wall:

I: What made you change your mind about that?

S: Um. I don’t know. Maybe unconsciously cause of what she said.

I: OK. What was it about what the student said that kind of influenced you?

S: Um. How she said you push against the wall. Um. She said it’s the same as when you stoppushing the wall and you take your hands off, there is no more force. That’s true. (year 10)

The remainder of the students either referred to other parts of the text as having a major influ-ence or just considered that it made sense to them in a general way. For example:

S: I was sort of seeing one way and when I read that that way it seemed more logical.

I: Was there any particular part of this which particularly sort of struck you?

S: Um not really. I just sort of thought about them both. It seemed more understandable thanwhat I said first. (year 6)

Table 1 presents other examples of students’ comments about their learning.It was interesting that the delayed posttest recorded a lower percentage of conceptual

change that the immediate posttest. There was a small number of students who stated after theimmediate posttest that they had revised their conceptions but then reverted back to the alter-native conception in the delayed posttest. Some of these students commented that they haddiscussed the examples with their peers during the intervening period and this had influencedthem, whereas others appeared to change their minds again spontaneously:

I: What made you change your mind [again]?

S: When I went home I was thinking about it.

I: What made you change your mind?

S: Well, someone throws a ball up. It’s still going up, so there is still a force pushing it up.(year 10)

Students Who Did Not Revise Their Conceptions. The students who showed no evidenceof conceptual change were also asked to comment on the text after they had completed theimmediate posttest. Their comments indicated that they did accept the text as being the re-sponses of “another student” and that they were happy with their own answers in comparison.For example:

I: How do you feel about that difference [between your answer and the text]?

S: That person thinks another thing.


I: Are you happy with the answers which you gave compared to the answers which the otherstudent gave?

S: Yes

I: And why do you feel that?

S: I just feel they’re right. (year 6)

Comments such as, “It’s just their opinion. There’d be a force pushing up because when youpush the ball up with your arm there’d still be force till it falls down” and “I think there wouldbe a force because the ball’s been thrown upwards hard and it’s still going up. Like, if therewas no force it wouldn’t go up” were common.

However, a small percentage (8%) of the year 6 students who had maintained their concep-tion of a motion–force then stated that there was no difference between their answer and the


answer of “the other student.” The inference to be made from this was that, for these students,the text had failed to create cognitive conflict (Hashweh, 1986). For example, one studentstated:

They are really the same when you think about it, because even though they haven’t shownthat it’s going up you don’t really need to because the push is already showing that it’s beenpushed and then it comes down again anyway. So it’s just the same. (year 6)

This viewpoint (that there was no conflict) could not be identified in any of the year 10 stu-dents.

Students’ Responses to the Text

The students’ statements were also examined to establish the extent to which the techniquewas in fact student-centered, the extent to which the students comprehended the text, and theextent to which they may have been influenced by the presentation of the text.

Student-Centeredness of the Text. The students appeared to accept the text as being “theresponses of another student just like you.” None of the students queried this aspect of thetext. In fact, when the students were asked to describe the main idea in the text a number ofresponses indicated that they accepted this at face value by applying their own gender to the“other student”:

Well she’s saying that she doesn’t think there’s any force going up on the ball. She thinks it’sall going down from gravity. And she doesn’t think it’s got any force going up because it’s thehand that starts it off and it still goes that way sort of thing. (year 10 female)

He’s saying or she’s saying that he’s pushing the ball up and after that there’s no more force.(year 6 male)

Comprehension of the Text. To determine students’ comprehension of the text their descrip-tions of the main idea in the text were classified into two groups. Those students who describedthat the text was mainly stating that there was no force pushing the ball after it had left the per-son’s hand were considered to have a good comprehension of the text. For example, studentsmade statements such as “Once the ball’s left the hand the hand’s not making a force” (year 6),and “He said that there was no more force pushing it upwards once it had left the hand” (year 10).The majority of the students in both groups, 59% of the year 6 students and 76% of the year 10students, demonstrated a good comprehension of the text. (Note, however, that there was not astrong relationship between those students who demonstrated a good comprehension of the textand those students who revised their conceptions: x2 5 .921, df 5 1, N 5 40, p . .05, for year 6;and x2 5 .005, df 5 1, N 5 47, p . .05, for year 10.) It can therefore be concluded that the textwas student-centered and that the majority of the students did understand its content, although theyear 6 students possibly to a lesser degree.

Presentation of the Text. The authors had anticipated that one potential problem with thetext would be that students could be unduly influenced by surface features of the presenta-tion of the text, rather than its actual content. For example, year 6 students especially could


be swayed to thinking that the “other student’s responses” may have been more powerfulsimply because there was a lot of clearly presented information on the page. It was found,however, that this was not a significant factor in the results. Of the students who revised theirconceptions only one referred to this aspect of the text as being a reason. This (year 10) stu-dent stated only that “They sort of explain it more thorough.” Although some of the otherstudents did refer to this aspect of the text, it was not enough to change their opinion. For ex-ample, both of the following students maintained their conception of a motion– force in theposttests:

I: What do you think about what this other student wrote?

S: It’s different . . . Theirs would probably be more correct.

I: Why do you say that?

S: I don’t know. They probably know more about science.

I: What makes you think that?

S: I don’t know.

I: Are you happy with your answer for that [the posttest]?

S: Yes. (year 6)

and:

I: What did you think of what this other person said . . .?

S: How I’m reading it it sounds like they know what they’re talking about.

I: Are you happy with what you said here [responses to posttest]?

S: Yep. (year 10)

DISCUSSION

The results of the pretest indicated that a majority of students in both year 6 and year 10held the alternative conception that motion-implies-force. Other studies have found that themajority of primary students, especially in the older years, do hold very clear alternative con-ceptions about aspects of mechanics (Eckstein & Shemesh, 1989; Whitelock, 1991). The re-sults are also in close agreement with other studies that have investigated the occurrence ofthis alternative conception among students aged 15–16 in Australasia (Gunstone, 1990; Osborne, 1981).

It is clear that many of the students in the present study did experience conceptual change.The responses of these students indicated that they had revised their conception of the forceson the ball in instance 1, and were able to apply their new understanding to other contexts.The students also demonstrated metacognition of the process by describing and reflectingupon their change of view. Metacognition, or “student directed formative evaluations of theirown learning” (Gunstone, Gray, & Searle, 1992, p. 177) is considered to be a powerful indica-tor of conceptual change.

The results however, offer no support for the notion of loss of plasticity. The delayedposttest indicated that 35% of the year 6 students and 44% of the year 10 students hadchanged their conceptions, although the difference in percentages was not significant. The textwas apparently unable to generate cognitive conflict in a small number of the year 6 students,but the majority appeared to have no trouble conceptualizing the situations presented to themor describing their responses.


Level of Conceptual Change

Although students in the present study did demonstrate conceptual change it may have oc-curred at a relatively weak cognitive level. Hewson and Hewson (1992) described three typesof conceptual change: (1) “conceptual extinction” occurs when one understanding becomescompletely replaced by another; (2) “conceptual exchange” occurs when the student gains anew understanding but still remembers the old one (as when, e.g., “there has been a change ofmayor. Both people continue to live in the city, but only one person is mayor.” p. 61); but (3) “conceptual capture” occurs when students modify their existing conceptions by simpleincreases or decreases. Hewson and Hewson consider that conceptual change is usually repre-sented by the latter two categories, and that conceptual capture involves a lower level of diffi-culty. In the present study, the largest proportion of the students who revised their conceptionsindicated that it came about because the text pointed out that after the ball had left the per-son’s hand there was no more force making it move upward. Consequently, they were broughtto appreciate the crucial difference between when the ball is still in the person’s hand as com-pared to after it has left the person’s hand. Therefore, it appears to fit neatly into Hewson andHewson’s category of conceptual capture in that it is a clear case of a simple deletion from anexisting conception. Similarly, the students who indicated that it was the analogy that influ-enced them the most could also be placed into the same category as it also involved makingconnections to existing knowledge. It therefore can be concluded that the level of conceptualchange experienced by the students in the present study was comparatively weak, and thattheir conceptions of motion had probably only partly changed.

For students who hold it, an aristotelian view is a belief system which underpins all theirthinking about motion in the real world (e.g., Gunstone et al., 1981), so the complete changeto a newtonian view requires strong restructuring at the level of Hewson’s conceptual ex-change. However, the way in which this change is achieved is more problematic. It has beensuggested that the conceptual change from aristotelian to newtonian physics can only be ac-complished by a difficult or revolutionary process. Pines and West (1986) for example, use avine metaphor to describe conceptions, and state that:

The classic example of this clash between the vines is when the child’s Aristotelian-like view ofphysical causation and reality is challenged by the Newtonian physics taught in school. . . . Theresolution of such conflicts, when the two vines in toto clash, is a painful process, one that is diffi-cult for the student to accomplish. (p. 593)

Although this may certainly hold true for a large proportion of students (i.e., the students inthe present study who did not change their conceptions as a result of reading the text), thereappears to be a significant proportion of students (i.e., those who did change their conceptionsas a result of reading the text, and without any apparent difficulty) for whom it does not. Forthe students in the latter group, it is possible that conceptual exchange may involve a series ofrelatively painless, weak restructurings carried out at the level of conceptual capture, andprobably associated with different types of contexts.

From the perspective of the science educator then, there may be two types of students whohold the alternative conception that motion-implies-force. There are those for whom concep-tual exchange is likely to be a cumulative process, consisting of many small modifications oc-curring at the level of conceptual capture. In the present study, this group represented justunder half of the year 10 students who held this particular alternative conception (although itcould well vary with regard to other alternative conceptions). On the other hand, there are stu-dents for whom conceptual exchange is likely to be a more painful process that cannot beachieved through a series of small steps. This group represented just over half of the year 10


students who held the alternative conception. However, the eventual change to a theory-likenewtonian conception is likely to be a time-consuming process for both groups—the formerbecause of the large number of contexts of motion that may have to be dealt with one at atime, and the latter because of their resistance to conceptual change.

The Student-Centered Refutational Text

The alternative conception that motion-implies-force appears to be a difficult one to changeusing traditional techniques, particularly group discussion (Gunstone et al., 1981; Thijs,1992). Driver (1989) recognized that “there are topics where students are unlikely to generatethe scientific conception for themselves through exposure to critical events or peer discussionand that they require more support in the process of construction of a new theory” (p. 485).The results of the present study indicate that refutational text is a technique that can providethis support for some students. Similarly, Hynd, McWhorter, Phares, and Suttles (1994) foundthat a refutational text was more effective than either demonstration or student discussion inbringing about conceptual change with regard to Newton’s laws of motion. Guzzetti et al.(1993) have presented a metaanalysis of several studies that have provided evidence of howrefutational text is an effective technique for the remediation of alternative conceptions inphysical science topics.

However, the refutational text as used in the present study differed from these in two impor-tant ways:

1. It was only designed to eliminate the alternative conception—it did not attempt to re-place it with a more sophisticated newtonian view. It was therefore considerably sim-pler than other models.

2. It was student-centered rather than teacher-centered—it was presented as the re-sponses of “another student just like you” rather than as the correct answer. It thereforeencouraged a balanced reflection of ideas, and was also gender-sensitive, to the extentthat it could be interpreted as originating from a person “just like you” of either gender.

Thus, although the student-centered refutational text does not offer itself as a textbook-basedtechnique it could easily be used in, for example, a worksheet format and presented in con-junction with other types of learning experiences. Hynd et al. (1994) reported that students donot like refutational texts, but we suggest that the simplicity and student-friendliness of thetechnique as used in the present study would help to make it interesting to students.

However, only a minority of the students in year 6 and year 10 changed their conceptions asa result of reading the text. This implies that, when presented in isolation, this technique willnot result in mass conceptual change (or deep conceptual change). But it does have the advan-tage of being extremely time-efficient—students typically required less than 2 minutes toread the text—so its potential should be further explored. For example, some recent studieshave shown that combinations of techniques such as written text/demonstration (Hynd et al.,1994) or written text/computer simulation/demonstration (Hennessy et al., 1995) have provedvery successful.

Implications

Although the present study provided no evidence for loss of plasticity (at least with regardto this alternative conception) this should not be interpreted as a case for postponing the im-plementation of conceptual change strategies until year 10. The difference between year 6 and


year 10 was not significant. So it could be conjectured that at some time between these years apoint would be reached where the educational advantages, to individual students, of futureprogress through physics unencumbered by this alternative conception, would outweigh anyadvantage to be gained by postponing conceptual change strategies until year 10.

Furthermore, it would be surprising if educational level and cognition were found to be theonly factors that determine the success of a conceptual change strategy when applied to differ-ent age groups. For example, the present study used individual interviews, but the effective-ness of the student-centered refutational text when used with full-size classes of year 6 andyear 10 students is yet to be determined.

The researchers acknowledge and thank Associate Professor Phil Moore for his contribution to thisstudy.

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readiness to change the conception that “motion-implies-force”: a comparison of 12-year-old and...

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