Constructivism and evidence from children's ideas

LEARNING

James Stewart and Peter W. Hewson, Section Editors

Constructivism from Children’s

and Evidence Ideas

PHILIP JOHNSON and RICHARD GOTT School of Education, University of Durham, Leazes Road, Durham DHI ITA, United Kingdom; e-mail: [email protected]

The validity and reliability of the evidence from children’s ideas is analyzed from a constructivist viewpoint, and a guiding set of methodological principles for the gen- eration and evaluation of evidence is proposed. The principles seek to accent child and researcher “frames of reference” and so distinguish between the grounds on which interpretations are made. Drawing on the findings of a recent longitudinal study, the guiding principles are used to make a critical analysis of some well-known research studies in the field of chemistry. 01996 John Wiley & Sons, Inc.

INTRODUCTION: THE CONSTRUCTIVIST MOVEMENT IN SCIENCE EDUCATION RESEARCH

The 1980s saw an explosion in research focusing on children’s understandings within content-specific domains of science (Carmichael et al., 1990; Pfundt & Duit, 1994). The rationale underpinning the work has been the recognition of “children’s ideas” as playing an integral role in any teaching-learning process attempting to pro- mote a scientific understanding of a particular domain. What a child is “already thinking,” it has been argued, has a crucial bearing on how she or he might interact with teaching, and, therefore, has a determining role in any subsequent learning. That this may now seem “obvious” to anyone involved in science education is a tes- tament to the widespread influence of the “constructivist movement.” Although constructivism as a general philosophy has a long history (Hawkins, 1994), and major theorists such as Ausubel and Piaget are constructivist at root (Novak, 1985; Vuyk, 1981), the article by Driver and Easley (1978) is commonly taken to mark the begin- ning of the constructivist movement in science education. Here, as argued by Solomon (1 994), Driver and Easley redescribed children’s ideas and the language of

Science Education 80(5): 561 -577 (1996) 0 1996 John Wiley & Sons, Inc. CCC 0036-8326/96/05056 I - 17

562 JOHNSON AND GOTT

“alternative frameworks” was born. Children’s ideas, resulting from Piagetian-type clinical interviews, were elevated to a position of prime importance for their own sake. Driver and Easley commented as follows:

We suggest therefore that Piaget’s accounts of children’s thinking in the causality studies, as in others, are important documents but should be read for the indications they give of the content of children’s ideas and explanations, rather than as ways of assessing the development of underlying logical structures. On the related issue of the uses of Piagetian tasks for assessing pupils’ development in science, it would seem that more valuable information could be gained by both curriculum developers and the practising teacher through interviewing pupils in order to understand their ideas and ways of thinking about a topic in question (Whittaker 1975), rather than as a device for classifying pupils and prescribing programmes for them. (p. 79)

In her recent article, Solomon (1994) draws attention to areas where the practices of “constructivists” are actually at odds, or at least sit uncomfortably, with the constructivist philosophy itself. These are significant criticisms. In this study, we wish to draw attention to further, and, we believe quite fundamental, problematic aspects within the accumulating constructivist research in science education. Our concerns are with the “uncovering” of the “children’s ideas” themselves, and, therefore, relate to the validity and reliability of this “evidence.” In challenging the findings of some often cited research studies we will draw on recent research (Johnson 1995a) in the field of chemistry.’ Although we will be critical, it is important to state that these criticisms are made in a positive spirit and with a recognition of the debt that is owed to the earlier work of others. Moreover, in adopting a constructivist position on learning, we endorse the view that a better understanding of children’s thinking is indispensable to the development and improvement of practice in science education.

VALIDITY AND RELIABILITY OF EVIDENCE IN RELATION TO CHILDREN’S IDEAS

An implicit assumption of empirical studies reported in the constructivist literature, it seems, is that finding out what a child thinks is a relatively straightforward task. This, in part, may well account for the rapid growth of the literature (Marin & Benarroch, 1994). The interpretation of children’s expressions, gained via interview or survey, has generated a range of ideas which has become widely accepted, whether by accident or design, as a representation of what children think. There is now an es- tablished “content” of children’s ideas (Driver, Squires, Rushworth, & Wood-

’ This is a longitudinal research project which investigates the development of children’s concept of a substance. Component ideas under study were those of substance/object distinction, purity, state, change of state, chemical change, elements and compounds, and the particle theory. Four teaching units, directly concerned with the development of the concept of a substance, formed the background to the study. Data were collected over a 3-year period (1990- 1993), in an English comprehensive school, from a cohort of pupils as it moved from year 7 to year 9 (ages 1 1 - 14). The principal means of data collection was the pe- riodic interviewing of a sample of pupils from the cohort. There were five major interviews completed by 33 pupils out of an initial sample of 36.

CONSTRUCTIVISM AND EVIDENCE 563

Robinson, 1994). The claim is that these are the ideas about various phenomena that children have and bring with them to the classroom. The stance adopted in this study is that understanding what a child is thinking is not a simple matter and that a constructivist position carries with it a natural limitation that must be recognized, and, therefore, that this claim must be treated as “not proven.” In particular, there are important methodological implications in relation to the validity and reliability of evidence. By validity we refer to the question of whether the data and their interpretation are that which they purport to be (construct validity). By reliability we mean the replication, on other occasions and in other contexts, of the evidence. The two, of course, are interrelated and it is important to appreciate that “reliability is a necessary, but- not sufficient, condition for validity” (Kempa, 1986, p. 37). Valid and reliable evidence would derive from a genuine part of a child’s thinking-something that is “really there.” A supposition that children “will have ideas” is not a sufficient basis for according such a status to any response. Lythcott and Duschl have examined such issues (Lythcott & Duschl, 1990), and we would seek to emphasize the importance of their warrants (which we will incorporate in our arguments). However, we wish to expand upon these and take matters further. Our thesis will be developed from well known “first principles,” and, in this respect, we aim to pay “attention to the whole argument” of constructivism as a worldview backing research of this kind (Lythcott & Duschl, 1990).

UNCOVERING CHILDREN’S IDEAS: METHODOLOGICAL IMPLICATIONS OF A CONSTRUCTIVIST POSITION

Constructivism and Communication-The Need to Recognize an Uncertainty Principle

“Finding out” what a child thinks rests on an interpretation of a child’s response to a researcher’s question. What are the implications of a constructivist position for this process? Each person makes his or her own sense of the world, and can only use what he or she already knows (existing cognitive structure) to do this-we will call this a “frame of reference.” It follows that each person’s frame of reference differenti- ates hisher world to different extents and integral to this is language-the meaning of words. Given this, there is an inbuilt uncertainty in any communication between two individuals. von Glasersfeld (1990) comments on the challenge a constructivist position poses for communication as follows:

Put in the simplest way, to understand what someone has said or written means to have built up a conceptual structure that, in the given context, appears to be compati- ble with the structure the speaker had in mind. This compatibility, as a rule, mani- fests itself in no other way than that the receiver says and does nothing that contravenes the speaker’s expectations. From this perspective, there is an inherent and inescapable indeterminacy in linguistic communication. (p. 36)

There is always what we will call a “translation interface” for the communication between two individuals. Applying this notion to the process of eliciting a child’s ideas, we can see that the translation interface is traversed twice (Fig. 1). At each


Researcher‘s Child‘s frame frame

Interface

Child‘s interpretation

of the question

Child‘s t response

1 Researcher‘s

question

Researcher’s interpretation of the response

Figure 1. The translation interface.

“translation” differences could arise. The child could be answering a different question to the one the researcher thinks he/she has asked:

Teachers, in their own differently ordered minds, can often convict children of error, when in fact, the children’s statements are right answers to questions different from those the teachers thought they had asked. (Hawkins, 1983, p. 74)

On the other hand, at the second crossing, the researcher could interpret the child’s expression in a way that was not the meaning of the child. Piaget (1977) warns of this danger of interpreting a child’s response in adult terms, that is, interpreting a response given within one frame of reference in the terms of another:

When the child grasps an object in order to suck it, look at it etc., he seems to differ- entiate the means from the ends and, consequently, set a goal in advance. But, for want of an obstacle capable of attracting the child’s attention, nothing warrants attributing these distinctions to the subject’s consciousness. . . . It is therefore the observer, and not the subject, who makes divisions in the case of such schemata. (Piaget, 1977, p. 256)

The passage above refers to sensorimotor actions but applies equally well to verbal responses. Here, this may be a quite unconscious interpretation from within the researcher’s frame of reference which fails to recognize that the child’s frame may be quite different.

This “translation interface” is more than a matter of transliteration; it is the underlying meanings which can differ rather, than just the words used to convey them. The researcher’s frame constructs and gives meaning to the question. It is then within the child’s frame that a meaning to the question, in turn, is constructed. When that operation then has to be used in reverse for the child’s response, the possibility, even the probabil- ity, is that this will lead to “findings” which are at best only a fragment of what the pupil thinks (about that which the researcher wants to ask), and at worst quite disconnected from it. Duit (1995) draws attention to the “utmost importance” of this “hermeneutic cir-


cle” and notes that many researchers and teachers (the arguments apply equally to any “teaching” situation) do not appear to be “aware of it” (p. 282).

Does this mean the enterprise of finding out what a child is thinking meets an in- evitable impasse and so is doomed to failure? We think not, but wish to emphasize it is more than simply asking a child a few “key” questions and then categorizing verbal responses according to forms of words. Scrupulous attention must be paid to these fundamental constructivist limitations. With such issues in mind we feel that efforts must be directed at the development of a “neutral ground” between researcher and child.

A “Neutral Ground”

Figure 2 adapts Figure 1, and now shows an area of neutral ground set between researcher and child. We define “neutral ground‘’ as that in which a largely (but never completely) undistorted communication takes place between child and researcher. The child understands what the researcher is asking in the meaning intended by the researcher, and the researcher understands the child’s response in the meaning intended by the child. The neutral ground will be a much more limited affair than either the researcher’s or child’s own frame of reference. It cannot be called “common ground,” in the sense of equivalence, since such a claim is precluded by the fundamental constructivist principle. Kelly argues that no one is completely able to construct another’s constructs (Kelly, 1955). A neutral ground is the best we can aspire to.

We propose that there is a core of three basic methodological principles that should guide our efforts to establish and develop a neutral ground. These are: that the task be neutral; interpretation takes place on the neutral ground; and that “triangulation” should be seen as a priority. It may seem somewhat paradoxical, after what has been said earlier, to invoke a neutral ground within our principles. However, it must be recognized that there is an inescapable, and highly intimate, interrelationship between “means” and “ends” in a matter such as this. We will now discuss each of the principles in turn, giving some brief illustrations. A fuller examination of some research findings then follow.

frame

Neutral B Figure 2. A neutral ground between researcher and child.

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“Neutral” Tasks. By “task” we mean the totality of any object/event and associated verbal questions. The task given to the child must attempt to be “neutral” in relation to the researcher’s and pupil’s frames. “Neutral” means one that is accessible to both and does not in itself significantly constrain thinking and possible responses -a dif- ficult challenge since the pupil’s understanding is the endpoint of the research, but a necessary one if that endpoint is not to be precluded by the tasks and questions. This principle is often enunciated in guidance with respect to leading questions (Bell, Osborne, & Tasker, 1985), and Lythcott and Duschl’s (1990) first warrant derives from such considerations:

Novel verbiage used by an interviewee (verbiage that has not been introduced into the conversation by the interviewer) reflects a part of the cognitive system of that student, that is what he or she knows. (p. 45 1)

For example, for a task involving the condensation of atmospheric water vapor on a cold surface, Osbome and Cosgrove (1983) ask “Where has the water on the out- side of the jar come from?” (p. 832). However, this question derives from a frame of reference which demands conservation-it says the water has to have come from somewhere. A child might not see things in this way, but if asked for a source, might invent a reply to satisfy a request he or she does not understand the reason for. A more neutral question would be “how come water is now on here?” It may well be that the two questions elicit similar answers, but the response to the latter must carry a greater validity in terms of revealing a child’s own thoughts. However, as we shall later illustrate, we feel attention must be given to the totality of a task and not just the associated verbal questioning.

interpretation on Neutral Ground. Here the researcher must be alive to any number of possibilities of meaning in a child’s response. Interpretation must attempt to understand what a child is saying on his or her own terms and the researcher must guard against imposing meanings from his or her frame of reference. Insofar as it exists, interpretation must take place within the neutral ground. Lythcott and Duschl’s second warrant with respect to words with scientific meaning (which in practice could be al- most any word) has application here:

Words with scientific meaning, may only have the meanings ascribed to them that are given in the conversation by interviewees, whether introduced by the interviewer or the interviewee; common meanings, scientific or otherwise, may not be inferred. (P. 452)

Meheut, Saltiel, and Tiberghien (1989, on a task where soot forms on a glass surface above a candle flame, report: “In contrast, 39 per cent of the students suggested a change not in the combustible material but in the glass placed over the candle: ‘because it bums the glass”’ (p. 86). This interpretation endows “bum” with its scientific meaning. Given that children use “burn” with a variety of different meanings (BouJaoude, 1991) this claim seems highly questionable. A more likely interpretation, and one supported by recent research (Johnson, 1995a), is that pupils are using


“bum” simply to confirm that “the glass goes black” (one of its very common everyday meanings), without any implication that they thought there had been a “change in the glass.”

This suspension of judgment on the part of the researcher, particularly with respect to “scientific words,” is perhaps the most demanding condition to observe. There is always the danger of overinterpretation. It should also be noted that asking questions with such scientific words, rather than about scientific words, is likely to place a task out of neutral ground, unless one can be confident that a child does understand the scientific meaning.

“Triangulation.” Even if tasks are apparently neutral, and analysis and interpretation avoids reading unintended meaning into a child’s words and captures the essential meaning, there is always the prospect that it is all of little significance. McClelland (1984) warms of the possibility that pupils may never have thought reflectively about a particular phenomenon and notes the strategy of “instant invention.” Piaget ( 1929) draws attention to the possibility of “answers at random” (a person has no interest in the question and gives the first thing that comes into his or her head) and a “romanc- ing response” (an invented answer that the person does not really believe in). Hills (1 989) comments thus on the views pupils espouse:

Do they represent a position in which they have some continuing stake? Or are they transient artifacts of the research design, including the tasks employed, the questions asked, and so on? (p. 184)

Validity is being questioned on the grounds of reliability. If a pupil does have a particular understanding, as part of hisher frame, then one might expect this to shape responses in related tasks. In the first case these might be instances of the same kind of phenomenon, such as different examples of chemical change, although we must be aware that such a choice imposes an interpretation from the researcher’s frame. An- other possibility would be related phenomenon where a good proportion of the “in- gredients” are the same; for example, the evaporation of water at room temperature and the condensation of atmospheric water vapor. We see these as contributing to a process of “triangulation.” (Of course, it may be that a child does not seem to hold any such connections: we would still argue that these are very valuable data in relation to what he or she is saying.) A particularly important form of triangulation would be to explore component aspects of an event. For example, to interpret a child’s response to a task involving the change of mass for a chemical change such as copper to copper oxide, the child’s views on the mass of a sample of powder compared to a parent “lump” and the mass of a sample of oxygen would be very helpful, if not essential. Triangulation addresses not only the issue of reliability but also increases our confidence in the validity of evidence (which reliability of itself is no guarantee).

A criticism we have of much of the research into children’s thinking is that studies have tended to be compartmentalized and have not sought to develop an understanding of a child’s responses over a range of related ideas. More particularly, in seeking to explore the thinking in one topic, studies often seem to assume that supporting concepts are unproblematic, and yet those same concepts are often the principal focus of


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other studies. For example, Longden, Black, and Solomon (1991) used particle dia- grams to explore children’s interpretation of dissolving. They appear to have assumed that all the children would take the particles to be the substance, and yet other research has reported that this is not necessarily so (Renstrom, 1988). Indeed, Johnson (1995b) has found 33% of a sample of 1 1-year-olds (n=33) holding a view in which the particles are not regarded as the substance. This, unlike the age 11 sample of Longden et al. was after a first teaching of a basic particle theory.

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Developingthe ; neutral ground ;

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Deve/oping the Neutral Ground. If the task and the analysis and interpretation are necessary considerations in defining the neutral ground, triangulation is the process by which the neutral ground can be developed in depth as well as breadth. As the neutral ground grows, so does its resolution through a process of successive approxi- mation-a child’s utterances become more precisely understood, questions become better targeted. In terms of understanding a child’s view there is a “snowball effect.” The crucial point is that the child’s frame must be the driving force in the development of the neutral ground (Fig. 3) . Confidence in the validity and reliability of evidence increases as the neutral ground is developed and so depends on:

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the researcher must guard against interpreting through hislher

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0 the number of “measurements” that are made, at different times and, ideally, with different instruments; and the range of contingent ideas that are examined.

We therefore see “triangulation” as a very important principle; it is more than just a question of reliability. (We are not, of course, making any claims here about sample size and generalizability of findings.)

In summary, we wish to argue that the validity and reliability of evidence relating to children’s ideas is dependent on the degree to which a neutral ground has been es- tablished and, as such, there are no absolutes.

EVALUATING RESEARCH INTO CHILDREN’S IDEAS

We would suggest that research studies can be evaluated in terms of our three methodological principles. Table 1 gives four possible outcomes of such an analysis. The answers to the questions in Table 1 are rarely as clear cut as a simple yes/no, the complexity of real situations sees to this. However, we will now look in more detail at some well-known research reports and present three case studies, one focusing on each of our principles, to illustrate our concerns. Again, we emphasize that we are choosing from these studies with a view to what we hope is constructive criticism, and with the intention of stimulating a reevaluation of existing data.

TABLE 1 Using the Three Methodological Principles to Evaluate Research

Is the Interpretation Is the Task on of Responses on Is There

Neutral Ground? Neutral Ground? Triangulation? The Evidence

No

Yes No No The raw data is potentially

The raw data is very suspect. Findings are not valid.

useful, but needs reinterpreting. Validity and reliability require confirmation through triangulation.

The evidence is valid, but is limited. Confidence in validity and reliability needs establishing through triangulation.

the validity and reliability of the evidence.

Yes Yes Yes There can be confidence in

Yes Yes No


An implicit assumption in what has been said so far, and, we believe, within the reported research into children’s ideas, is that the underlying science itself is unproblematic; that is, its contingent ideas and language are well understood, thus constituting a neutral ground among scientists/researchers (this makes no comment on the epistemological status of such knowledge). However, our first case study, in a very familiar area of science, suggests this assumption should not be taken for granted, and starts with an examination of the underlying science.

Case 1 :The Task Is Not Neutral

This case concerns children’s ideas about the meaning of “solid.”

The Underlying Science and Different Frames of Reference. Classification into “solid” and “liquid” relates to the characteristic properties of a sample of a material (material is used as a general term to include elements, compounds, and mixtures). The concept of a “material”, as an identifiable kind of stuff, is independent of any particular object, but there is a problem here, in that a material cannot exist without some physical form; the material is imprisoned in a form. There always has to be a sample of a material, and that sample is an “object” of some sort which, itself, entails an “amount” of material and a “design.” This definition of object encompasses familiar “objects,” such as tables, chairs, and “lumps,” to those less thought of as objects such as “drops” and “bubbles.” In any consideration of the properties of “materials,” the differentiation, and relationship, between material and object is of crucial concern.

We need to distinguish between what can be ascribed to the material of the object and what can be ascribed to the object of the material-that is, to “amount” and “design” (Vogelezang, 1987). An apparently simple property, such as tested “strength,” is related to the type of material, amount of material, and design of the object (also related to crystalline structure of the material). A careful control of amount and design is needed to compare the strengths of different materials. Melting point is a characteristic property of a material, and, as such, is independent of the object, but all else connected with the actual event of melting, is, in part, a function of amount of material and design of object.

Questions relating to properties are inevitably bound up with the inextricable link between material and object. The scientific concept of a state relates to properties that directly concern the material of the object, rather than the object of the material. In the case of the solid state we have a further consideration in that objects can make other objects. For example, a “ball” of iron wool is composed of “strands” of iron. Here we might call a strand the primary object, and the ball the secondary object, in the sense that the strand is directly of the material the “thing” is made from. The identity of the material rests with the primary object. Both primary and secondary objects have an associated “amount” and “design”; strands can have a varying cross- sectional area and shape, and the ball as a whole has a shape and an amount of strands. In a case such as this, answers to questions of properties can depend on whether the focus is on the primary or secondary object. If the “ball” is taken as the object, it can be easily squashed to a smaller size, if an individual strand is taken as


the object, then it is not being compressed. The ball might be regarded as “light” for its size, a strand might be regarded as “heavy” for its size. By switching the focus between the primary object and secondary object we can have seemingly opposite views. In the same way, a “heap” of iron filings can be thought of as a secondary object and each filing a primary object.

Everyday meanings of “solid,” such as “no holes,” “not hollow,” “hard,” “strong,” and “a decent-sized lump,” cover a wide scope but essentially refer to the object of the material (amount and design) rather than the material of the object. In the case of primary and secondary objects the reference is to the secondary object. The focus of the everyday and scientific meanings are different, the former is largely on the object of the material, whereas the latter is on the material of the object (although not a specific material). According to everyday criteria, our ball of iron wool would not be regarded as solid. The explication of “solid” is not a simple matter.

Children’s Understanding of Solid. Stavy and Stachel(l985) have reported findings from a cross-age (5- 13) study exploring children’s understanding of the meaning of “solid,” where the task involved the classification of a range of samples of materials. For such a study, we argue that the tasks must:

recognize the distinction between object and material in the underpinning science to the task; and use questions which, at least, cater to frames of reference which are “scientific” and “everyday.”

We see these as essential conditions for producing valid data on neutral ground. However, Stavy and Stachel describe the following task:

Students were first shown two solids-a rock and a stick-and were asked if there was anything common in both. If they did not use the term “solid” in their response, they were told that both objects are solids, and were then asked if they knew what “solid” meant and to give examples of other solids. . . , These two solids [and two liquids] served as reference items with which the rest of the materials were compared. (p. 409)

The “rest of the materials” included a mix of primary and secondary objects. The choice of a rock and a stick as exemplars of the solid state obscures the differ-

ent foci of the everyday and scientific meanings of “solid,” since these objects easily qualify as solid by everyday criteria. In the task there is nothing to suggest to the pupils that this is not the meaning being asked for. There is no mention of the material as such, and, although the concept of a state is generic and not linked to specific materials, naming the material might at least encourage a child to consider this as a question related to the material of the object and not the object of the material. After all, it is the material which is in a state.* Indeed, for those not using the

’Here we would point out that the purity of a sample of material is an important consideration in relation to a classification into one of the three states (Johnson, 1996).


word “solid” the language seems to explicitly direct attention to the object of the material-“they were told both objects were solids” (and this was for over 80% of the sample).

Therefore, it seems quite possible that the children were answering a different question to the scientific question of state. Certainly, their responses, where they gave descriptions of the exemplar objects and had difficulties with secondary objects (powders, wool, cloth, sponge) are entirely consistent with this interpretation. Stavy and Stachel state:

These results indicate that practically all children (from the first grade) have some knowledge of the concept of “solid” (or an equivalent), but this is much more limited

tban [be concept of an aduk or scientist, and includes mainly rigid solids, and ex- cludes non-rigid solids and powders. (p. 415)

Children may indeed have difficulty in differentiating between the material of the object and object of the material, and therefore have a more limited conception of “solid.” However, the crucial point is that the instrument of this study does not allow such a conclusion to be made. If a child answers a question he or she has good reason to think is about the object we do not know whether he or she might be able to differ- entiate between material and object and, if so, what he or she might be able to say about the material of the object in relation to its state. One cannot judge pupils’ responses against those one might expect for a different question. The task is set within the implicit assumptions of the researcher’s frame and so we must acknowledge that it could fail to engage with a child in any valid way. Here we would add that evidence from Johnson ( 1995a), where the material -object distinction was addressed, would caution against any suggestion of widespread difficulties with the understanding of “solid” which are an inherent limitation in children’s thinking (particularly by age 11).

Case 2: The Interpretation Is Not on Neutral Ground

identifies five categories of response: In a review of research studies concerned with chemical change, Anderson (1990)

Five categories of answers, or transformation models, can be distinguished in the large amount of material collected, namely, disappearance (A), displacement (B), modification (C), transmutation (D) and chemical interaction (E). Characteristic of A, B, C and D is that the pupils imagine that a new substance appears, and an old one disappears, as a result of a separate change in the original substance, or possibly changes, each one separate, in several original substances. The original substance can in itself interact with another substance, but it does not form a new substance with it. (p. 55)

The point we make here is that the interpretation of what the children are saying is largely being driven by the researcher’s frame of reference and is not taking place on neutral ground. By mixing in the researcher’s frame of reference there is the danger of attributing ideas to children that they do not have and producing categories that are


somewhat self-contradicting. The interpretation seems to assume that the children are seeing the changes as a change of substance-that is, what is understood as a chemical change in the researcher’s frame of reference-“ . . . the pupils imagine that a new substance appears, and an old one disappears.” However, there is no reason to suppose this is how children imagine what has happened. Yes they see a change in appearance, but this does not necessarily mean they understand this as a change of substance. Indeed, the study by Johnson (1995a) suggests that children find the idea of a substance with its own identity changing into another substance with its own, and so different, identity very strange and that this is not a natural part of their thinking. The key point is that we must be very careful not to claim these as children’s ways of explaining chemical change as we understand the term. To be on neutral ground we must entertain the possibility that the child does not have an idea that rec- ognizes chemical change as a possibility, let alone have a means of explaining it (in this sense, although directed at the same event, the child is answering a different question). As it is, categories A, B, and C, do not call on this idea. B does seem to recognize there is a new substance, but there is no idea that it could result from a change of the existing one. C actually refutes it and so contradicts the notion that it is a chemical change. In the case of A, we must be careful not to attribute children with ideas for the annihilation of matter. A child saying that something disappears may just be saying that he or she can no longer see it (which is accurate), without any implication of what it means has happened to it. Category D seems a very clear example of the danger of interpreting a child’s expression in our meaning of the words-that is, overinterpretation. The following phrase in response to the event of “heating iron wool” is given in support of this category:

The iron wool that has burnt has turned into carbon. Carbon weighs more. (p. 57)

A child saying the black powder appearing on heated iron wool is carbon could simply be giving this as a description (it does look like carbon), and the child uses “carbon” as a term for something black. We cannot assume carbon means an identifiable substance for the child, which is different from iron. Furthermore, if, and Johnson’s findings suggest this is quite likely, a child does not have the idea of substances transmuting into different substances as something that can happen (which, after all, is what a chemical change is), by definition, he or she cannot mean one element (as we understand the term) changing into another element. Far more corrobo- rating evidence would be required before we could claim this is what a child is meaning by such words. This now brings us to the role of “triangulation.”

Case 3: The Need for “Triangulation”

Change of state for water has received considerable attention in the research literature. Here, the article by Osborne and Cosgrove (1983), covering boiling, condensation of “steam,” evaporation at room temperature, and condensation of atmospheric water vapor at a cold surface, has been influential. A common response in relation to both boiling and evaporation at room temperature is that the water changes into air. The following interview extract is given as evidence:


“It is sort of sucked up into the air.” (“Is it still water?”) “no” (“What does it change into?”) “air.” (p. 831)

In a later publication (Schollum & Osbome, 1985) this extract is used in support of the following statement:

One view we found prevalent with young children (Osborne and Cosgrove 1983) was that water on the plate changes into air. (p. 59, authors’ own emphasis)

Does this child mean a change of substance in the sense that a scientist regards water and air as different substances (in fact air as a specific mixture of substances)? Given children’s difficulties with the notion of chemical change it is perhaps unlikely that this sort of change is meant. What is more, it should be noted that the idea of a “change” was introduced by the interviewer. Again, we must be careful not to interpret the child’s words in our frame of reference and must try to stay on neutral ground. Anderson (1990), drawing on their study, has classified the following “ex- planation” for the bubbles in boiling water under the “transmutation” category:

The heat of the element could turn some of the water into air. (p. 59)

However, this is qualified by:

The word air might also refer to an undifferentiated idea of something gaseous. (P. 59)

Anderson’s “might also” is now moving back to the neutral ground. Our point is that there is not really enough “to go on” for us to make any strong claim as to understand what this child is saying. Johnson (1995a) found children giving similar responses; however, data in related areas was also available and proved invaluable. P brief sketch of some of the responses of one child (H) are given below to illustrate our point.

In the same interview in November of year 8 (age 13), child H’s responses to the following phenomena were: (a)

(b)

Evaporation of water from a saucer at room temperature:

Condensation appearing on a cold Coke can, after being reminded that the can had been wiped dry:

“. . . might be air from the room going on there . . . it’s cold and so it changes back into water because it’ going down the system again.”

“. . . not all of it as must be some left in the air-atmosphere . . . because in winter it’s cold and all air doesn’t turn into water and snow . . . only some of it”

Examples of chemical changes, malachite to copper, iron to rust, and bread to charcoal. When asked about the number of substances for each pair, the response was “one.”

the water ‘ I . . . turns into air.”

Asked if all the air in the room would go to be water H commented:

(c)

“. . . just the same but in a different form.”


H is consistent in her responses for parts (a) and (b), and her last comment in (b) suggests a distinction between “air that’s been there forever that hasn’t been water and air that was water” (to use the words of another child). Her response in part (c) shows no recognition of the idea of chemical change. Therefore, it seems unlikely that H was meaning a transmutation of water into air in part (a), and was using ‘‘air’’ as a general term for a gas, but at the same time did seem to recognize that there were different types of gas. H’s responses in earlier interviews in year 7, and later interviews in years 8 and 9, to the same and other related events (e.g., boiling water and evaporation of “meths”), although showing important changes, were also consistent with this interpretation of what she was saying at this point in year 8, as indeed was her use of particle ideas. Therefore, on this interpretation, H’s response to the question of evaporation does not appear to be anything which is greatly at odds with the accepted science view. (The same cannot be said about chemical change.)

This very limited sample of the full data on child H illustrates how the validity of our interpretations can increase with the development of the neutral ground through triangulation. We can never say that evidence is completely valid and reliable. But we feel it is possible to reach a point where we can begin to feel fairly confident in our understanding of what a pupil is saying; that is, there exists a sufficiently well- developed neutral ground within which meaningful discourse can take place.

IMPLICATIONS

We hope the notion of a “neutral ground,” and the attendant principles for its estab- lishment and development, will help in the quest for high quality evidence in this important area of research. Clearly, if children’s “elicited ideas” are to form the basis of subsequent teaching (Driver & Oldham, 1986) their validity and reliability are of paramount concern. To return to child H, solely on the strength of her response for evaporation, an attempt to convince her that water did not change into air would be quite inappropriate. However, even if evidence that stands up to scrutiny in terms of validity and reliability is collected, there is still the question of “what is to be made of it.” In other words, the evidence must be “weighed,” and only then can any implications for teaching emerge.

Such pedagogical judgments must take place within a framework which considers the relationship between teaching and learning. Space precludes a discussion of such issues here, but, in the light of what has been said we would like to make a few brief comments before closing. Lythcott and Duschl’s third warrant relates to the issue of “weighing” the evidence:

When verbiage of children, from interviews, is compared to segments of public domain science knowledge, goodness of fit can be assessed; so, verbiage that can be argued as being consistent in meaning with public domain science knowledge can be said to arise from that child’s scientific conceptions. Similarly, verbiage inconsistent with public domain science knowledge can be said to arise from ascientific conceptions. (p. 453)


We agree with the first part, given that the tentative nature of such a claim is recognized. However, in our view, the second part could be taken as an acceptance of children’s ideas at “face value”; a position characterized by their direct incorpora- tion into teaching. It is important to appreciate the distinction between a neutral ground and individual frames of reference (Fig. 2). Evidence that arises from within the neutral ground derives from a pupil’s own frame of reference. It is that frame of reference which we seek to change by teaching; that is precisely the aim of education. But, we argue, even where evidence is valid, we may still be a long way from understanding the frame of reference which produces the particular responses. A teaching scheme aimed at those responses, rather than the frame, must be problematic. Instead, we feel they should be regarded more as “signs” of understanding and efforts should be directed at identifying possible underlying “causes” for apparent differences from the science view. A child not having the idea of chemical change as a possibility, and so as an option in hisher thinking, would be an example of an “underlying cause.” Teaching must then seek to address these “causes.”

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Accepted for publication 22 January 1996

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Constructivism and evidence from children's ideas