exploring the link between students' scientific and nonscientific conceptions

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q 1999 John Wiley & Sons, Inc. CCC 0036-8326/99/060639-15

Exploring the Link betweenStudents’ Scientific andNonscientific Conceptions

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

Received 9 February 1998; revised 22 September 1998; accepted 1 October 1998

ABSTRACT: In recent years, a large amount of research has focused on alternative con-ceptions, but some studies have shown that students may also have scientifically acceptableunderstandings in the same content area. The purpose of the present study was to inves-tigate whether these two types of understandings are linked, and if so, how. Individualinterviews were carried out with 63 11–12-year-old students and 44 15–16-year-old stu-dents. The interviews were designed to identify students’ conceptions of biological role(i.e., every living thing has a role to play in nature) as applied to a range of different typesof living things. A significant proportion of students had both an alternative conceptionand a scientifically acceptable conception. Their explanations indicated that they wereusing an “if . . . then” type of reasoning which linked the two conceptions. q 1999John Wiley & Sons, Inc. Sci Ed 83:639–653, 1999.

INTRODUCTION

There is now a considerable amount of educational research which shows that studentsdevelop their own ideas and beliefs about natural phenomena even before they have for-mally been taught science. When students are learning about science, they interpret anynew information in the light of these existing ideas and beliefs, which then become mod-ified or revised. Although this constructivist view does have its limitations (Solomon,1994) it is still the dominant paradigm of learning in science (Carey & Smith, 1993; Driver,1989; Kuhn, 1993; Osborne & Wittrock, 1983) and underpins most of the current researchin this area.

One of the important findings of this research is that many of the beliefs and under-standings which students have are quite different from the accepted scientific viewpoints.The identification of these “misconceptions” or “alternative conceptions” has been the goalof many of the studies carried out over the last two decades (see Pfundt & Duit, 1991).Some of these studies, however, have indicated that students may have more than oneconception in a particular content area, and that different conceptions can be brought intoplay in response to different problem contexts. (In this study, the term “context” will beused to refer to the phenomenal setting of the task or problem, as used by Engel Clough,

Correspondence to: D. H. Palmer; e-mail: [email protected]

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Top of testBase of textand Driver [1986].) For example, Leach, Driver, Scott, and Wood-Robinson (1996) in-

vestigated students’ ideas about ecology and found that “Most pupils between the ages of5 and 16 are inconsistent in the form of explanation used in different contexts. For example,they may explain relative population size in different communities in different ways” (p.138). Watson, Prieto, and Dillon (1997) found that students’ ideas about combustion ap-peared to change according to the type of material that was burnt. Potari and Spiliotopoulou(1996) reported that students’ conceptions about volume were influenced by factors suchas the type of matter, its shape and its mass. Fischbein, Stavy, and Ma-Naim (1989) foundthat students’ “motion force” ideas were influenced by the features of the moving bodyand, in particular, its shape, weight, and function.

These types of results suggest that students’ understanding of a topic is fragmented, sothey do not have a scientist’s theory-like view of the world. DiSessa (1988) proposed that“intuitive physics consists of a rather large number of fragments . . . which I call‘p-prims’ (short for phenomenological primitives), [and which] can be understood as sim-ple abstractions from common experiences” (p. 52). He argued that a particular problemcontext will activate a particular p-prim and that this will determine the type of explanationthat the student will give. He further argued that this knowledge system is weakly orga-nized, so that students’ justifications typically lack depth, and their responses can oftenappear to be ad hoc in nature. Minstrell (1992) also proposed that students have pieces ofknowledge, which he called facets, and which are closely related to particular problemcontexts. For example, one specific facet could be “the bigger/heavier the object, the moreforce it will exert” (p. 115). This type of facet can be applied across a range of contexts,so Minstrell suggested that students’ intuitive ideas, rather than being ad hoc, may havean internal coherence that is not immediately obvious to the observer.

What is still not clear, however, is the status of the students’ scientifically acceptableunderstandings (i.e., beliefs that are in general agreement with those of scientists) and therelationship, if any, between these and the students’ other pieces of knowledge in the samecontent area. This is a significant issue—if, as we believe, students learn by making linksto their existing knowledge, then surely it is important that educators are able to identifythe students’ scientifically acceptable conceptions as well as their alternative conceptions.The former would presumably provide the solid learning base on which students couldbuild their knowledge and, although the latter do need to be effectively dealt with in theclassroom, it is difficult to see how this could be achieved without having an adequateunderstanding of the exact nature of any possible relationship between the two types ofknowledge.

It has been suggested that alternative conceptions and scientifically acceptable knowl-edge represent two completely separate ways of thinking with very little, if any, connectionbetween them. For example, Hawkins and Pea (1987) described the “two cultures” ofeveryday thinking and formal science thinking, and maintained that “the outcome of sci-ence learning can thus exist as a set of inert ideas that are not generative, nor interactivewith the explanations children have constructed themselves” (pp. 298–299). This viewemphasizes that the situation in which the knowledge is learned is an integral part of thatknowledge and, as schools too often concentrate on the transfer of decontextualized ab-stract concepts, the students are therefore unable to apply their school knowledge to realworld situations (Brown, Collins, & Duguid, 1989). On the other hand, Clement, Brown,and Zietsman (1989) showed that, along with their alternative conceptions, many studentsalso had an “anchoring conception” which the authors described as “an intuitive knowledgestructure that is in rough agreement with accepted physical theory” (p. 555), and whichcould be linked to their alternative conceptions via a series of related examples.

In summary, the aforementioned studies have indicated that, in any particular content

STUDENTS’ SCIENTIFIC AND NONSCIENTIFIC CONCEPTIONS 641


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entifically acceptable. However, the relationship, if any, between the two is still very muchan open question. The purpose of the present study is to investigate this issue with regardto one particular concept—biological role.

The Concept of Biological Role

The idea that all living things have a role to play in nature is one of the central principlesin ecology. The term “ecological niche” is used by scientists and by students at postsec-ondary levels of study to describe a species’ functional role in a particular community.This concept takes into account the habitat(s) in which the organism lives, as well as howit transforms energy in the system, how it behaves as it interacts with the physical andbiotic environment, and how other species react to it. However, at elementary and highschool levels of education (including all of the schools in the present study), the term nicheis not normally used, and an organism’s role in nature is usually studied in terms of itspreferred habitat, the food chains and food webs in which it is involved, and the structuraland behavioral characteristics that enable it to survive and interact with its environment.

Surprisingly few studies have analyzed students’ knowledge about this important con-cept. Munson (1994) found that students “do not understand . . . that each species hasunique needs, and therefore each species has a unique effect on an ecosystem. Instead,some students believe that the needs of a species are general and typical of similar speciesthat carry out the same role within the ecosystem” (p. 33). Leach et al. (1996) examinedstudents’ ideas about the closely related concept of interdependency of organisms, andfound a range of views from highly teleological reasoning (i.e., that patterns in naturewere planned in order to meet the particular needs of organisms) to more scientificallyacceptable ideas about competition between populations of organisms. Some research hasfocused on specific aspects of food chains and food webs (Adeniyi, 1985; Barman &Mayer, 1994; Gallegos, Jerezano, & Flores, 1994; Griffiths & Grant, 1985), but, in general,there is a paucity of studies concerned with students’ conceptions of biological role in itsentirety.

Following from the views of DiSessa (1988) and Minstrell (1992) as just described, itcould be assumed that students’ knowledge fragments about biological role would beclosely related to specific contexts. Therefore, one way to identify these fragments wouldbe to systematically present a range of contexts that are associated with the concept ofbiological role. Several studies have shown that different types of living things representdifferent contexts for students when they are applying their ideas in biology. For example,Kargbo, Hobbs, and Erikson (1980) found that, when children were presented with prob-lems about inherited characteristics, “the response pattern varied significantly accordingto the type of organism” (p. 140). Engel Clough and Wood-Robinson (1985) found thatmany students considered that intraspecific variation occurred in animals but not plants.Strommen (1995) investigated young children’s understandings of the features of livingthings and found that “properties were inconsistently applied across different types oforganisms” (p. 286). It therefore appears that the diversity of living things represents arange of contexts that are especially influential in students’ thinking, and for this reasonit was adopted for the present study.

The first aim of this study is to identify students’ alternative conceptions and scientifi-cally acceptable conceptions about biological role, as they are applied to a range of dif-ferent types of living things. The second aim is to investigate the nature of any possiblerelationship between these conceptions.

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The Sample

Individual interviews were carried out with two cohorts of students. The first cohortconsisted of 63 year 6 (11–12-year-old) students, who came from five elementary schoolsin a coastal city in southeastern Australia. The second cohort consisted of 44 year 10 (15–16-year-old) students who came from two high schools in the same city. Within each highschool the science students had been graded so that pupils of similar ability were normallyin the same class. In one school, four students (boys and girls) were interviewed from eachof the five science classes, and in the other school three students (boys and girls) wereinterviewed from each of the eight science classes. The sampling technique consequentlywas designed to cover the full stratum of ability levels within each high school. The onlyvariation to this occurred when it was not possible to get enough student volunteers fromeach class. This happened in two of the classes, so students from comparable classes inanother school (not otherwise involved in the study) were substituted in their place.

The two high schools were located in different parts of the city, and each of them drewstudents from a range of socioeconomic backgrounds. The elementary schools were inwidely spread locations including the same general areas as the high schools. The samplecontained similar numbers of boys and girls—there were 33 boys and 30 girls in the year6 cohort, and 20 boys and 24 girls in the year 10 cohort. All the students were volunteers.They had been informed that participation in the study would not affect their grades, butthey were not forewarned as to the specific topic of the interview.

It was decided to include both year 6 and year 10 students in order to gauge the effectof high school science lessons. The year 6 students had not yet entered high school (whichbegins at year 7), but the year 10 students were about to move on to senior high school,in which science is no longer compulsory.

Interview Structure

All the interviews were carried out by the present author. They were audiotaped, andtypically lasted up to 15 minutes. The interview structure and the items were developedin a pilot study involving interviews with nine 12-year-old and five 16-year-old students.These students did not participate in the final study. The general structure of the interviewwas as follows.

First, the students were shown a printed word list of 16 items, which were all livingthings (see later), and were asked which of the things (the interviewer was careful to usethe word “things” rather than “living things”) would have a role in nature. The studentswere then advised that they could circle “all of them or none of them or any number inbetween.” These guidelines were also printed at the top of the list. The students were givenas much time as they needed to work through the items by themselves. Circling an itemtherefore indicated that it would have a role in nature (and the students’ later commentswere consistent with this interpretation). The students were then asked to explain theirresponses to individual items, with a view to identifying their basic conceptions aboutbiological role.

Second, the students were asked how they had decided which ones to circle and (ifapplicable) which ones not to circle. Then they were asked how they decide in generalwhether something does or does not have a role in nature in real life. The purpose of thisphase was to identify their reasons as to why they responded as they did, and any possiblelinks between the conceptions that they had displayed. Some probing or clarifying ques-



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they were not pressured.

List of Items

The word list was printed in large letters on a sheet of paper and was intended torepresent a diverse range of living things. An attempt was made to choose items that wouldbe well known to the students and, in order to facilitate this, the words were deliberatelybroad (e.g., “tree”, “worm”) and in most cases the organisms’ everyday names were used,rather than their scientific names (e.g., “seaweed” rather than “algae”). The items weregerms (bacteria), mushroom, seaweed, grass, tree, jellyfish, worm, starfish, flea, butterfly,beetle, fly, fish, snake, bird, and kangaroo. The kangaroo was included because it is a well-known Australian mammal. Due to the coastal location of this study, starfish, jellyfish,and seaweed were also familiar items. Students were rarely unsure what the items were,but whenever this did happen it was discussed with the interviewer until the student washappy to continue. To reduce any possible effect of the order of the items, they were mixedand the sequence was regularly changed throughout the study.

It was decided to use a word list because traditional diagnostic problems in biologyoften contain several other contextual variables to which students could perhaps respond,such as the specific habitat or community, and the use of different types of terminology(Engel Clough & Driver, 1986). It was recognized that the use of a word list would notcompletely eliminate other variables, but it was however an attempt to reduce their impact,while systematically including a range of items that represented the diversity of livingthings.

Coding of Responses

The groupings (described in the next section) were created after study of the interviewtranscripts. To check the reliability of the coding, a random sample of ten transcripts wasindependently coded by the author and a colleague. There were two responses on whichthe author and the colleague did not initially agree. After discussion and resolution of thesediscrepancies another random sample of ten transcripts was independently examined andagreement was found in every case.

RESULTS

An initial analysis of the data indicated that the students could be divided into two maingroups—the first containing those who did not appear to be affected by context, and thesecond containing the rest of the students.

Group 1

Students were placed in this group if they circled all of the items (thereby indicatingthat all the organisms would have a role in nature) and gave a reason or explanation thatconsistently applied to all of the items (thereby indicating that they were not influencedby context). Thirty-five percent of the year 6 students (16 boys and 6 girls), and 61% ofthe year 10 students (12 boys and 15 girls) were placed in this group. All the primaryschools and both high schools were represented. Interestingly, the year 10 students camefrom upper, middle, and lower ability classes in roughly equal proportions.

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roles. For the purposes of this study, a scientifically acceptable role was considered to beany type of interaction that an organism has with its environment (e.g., feeding relations,behavioral relationships, and provision and use of shelter). The examples below are somestudent responses (Y6 5 year 6, Y10 5 year 10) to the question “What would be the roleof this organism?”:

[Seaweed] Fish eat it and hide in it. (Y6)

[Fly] A fly would be to carry bacteria around. (Y6)

[Kangaroo] Just to stop plants from growing out of control. [How would they do that?]By eating them. (Y6)

[Tree] To provide shade. A home for birds. (Y10)

Some of the students in group 1 had a very anthropocentric (i.e., centered on humanneeds) view of the roles of certain organisms (e.g., “[tree] It produces oxygen for us tobreathe and without it we couldn’t live” Y10), but these responses were considered to beacceptable for the purposes of the present study because they still concerned the effect ofthe organism on the environment around it.

When asked to provide an explanation, each group 1 student gave a reason that con-sistently applied to all of the items in the list. The most common reason given by bothyear 6 and year 10 students was that they all have a role because they are all part of nature(used by 50% of the year 6 students in group 1, and 33% of the year 10 students in group1). The next most common reason was that they are all living things (32% of the year 6students in group 1, and 19% of the year 10 students in group 1). The remainder of thestudents gave a range of other reasons such as, “They all help the Earth” (Y6), “Everythingneeds to be there” (Y10), and “They all relate to each other” (Y10).

Group 2

Almost all of the students who were not in group 1 circled some of the items but notothers. However, there was a major difference within this group—some students couldbe identified as having an alternative conception, which they used as a reason for notcircling items, but other students could not be identified as having such an alternativeconception. This was considered to be an important distinction because it enabled a positiveidentification of their reasons for not circling items. Consequently, it was decided to dividegroup 2 into two separate subgroups.

Group 2A. This group consisted of students who held an alternative conception and usedit to reason that some organisms do not have a role in nature. A student was only consideredto have one of these alternative conceptions (they are described in what follows) if he orshe used the same idea for at least two of the items that had not been circled. This wasbecause the use of an idea on two or more occasions would presumably be an indicationthat it has some significance in the student’s mind, but the same idea expressed only oncecould be an artifact or a transient solution resulting from the interview situation (EngelClough & Driver, 1986).

Forty-six percent of the year 6 students (14 boys and 15 girls), and 18% of the year 10



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high schools were represented. Most, but not all, of the year 10 students were from middleand lower science classes. Several alternative conceptions were identified, and those usedby more than one student (and might therefore have some significance within the popu-lation) are described next, in order of their frequency.

Alternative conception 1: Some organisms don’t have a role because they only have anegative effect on the things around them. The implication is that nasty, harmful, or un-pleasant organisms are not helping nature, so therefore they do not have a role. This ideawas used by 69% of the year 6 students in group 2A (all five schools were represented)and 75% of the year 10 students (including both high schools). It was most commonlyapplied to flea, fly, germs, and jellyfish, and to a much lesser extent to beetle, bird, seaweed,snake, starfish, and mushroom, but none of the other items. For example:

[Germs, would they have a role?] A lot of animals get sick because of germs so I don’tthink so. (Y6)

[Jellyfish, would it have a role?] No, not really. [Why do you say that?] Because they biteyou and it hurts, stings. (Y6)

[Fly, would it have a role?] No, because it just spreads germs. (Y10)

[Flea. Would it have a role?] Not really. They’re just there to annoy the dogs. (Y10)

Alternative conception 2: Some organisms don’t have a role because they don’t actuallydo anything significant— they are just there. This idea was used by 59% of the year 6students in group 2A (all five schools were represented) and 75% of the year 10 students(including both high schools). It was most commonly applied to jellyfish, starfish, kan-garoo, and seaweed, but it was applied to all of the other items to a lesser degree (except“tree”). For example:

[Starfish, would it have a role in nature?] Not really. It just kind of sits in rock pools, butit’s pretty I suppose but it doesn’t really do anything. (Y6)

[Butterfly, would that have a role?] No. [Why do you say that?] All it mainly does is justfly around. (Y6)

[Jellyfish, would it have a role or not?] I don’t think so. [Why do you say that?] Becausethey don’t seem to do anything. They just float around in the water. (Y10)

[Kangaroo, would it have a role?] No. I don’t believe it does. [Why is that?] It just doesn’tdo much. Jumps around in the bush. (Y10)

A number of students used both of the aforementioned alternative conceptions, and intheir minds the two ideas may have been similar. In other words, they may have believedthat an organism only has a role if it does positive things for the environment, but if itdoes nothing or negative things then it doesn’t have a role.

Other alternative conceptions. The following three alternative conceptions were heldby relatively small numbers of year 6 and year 10 students: (1) Some organisms don’thave a role because they are not part of nature. These students usually envisaged natureas a forest habitat, so any organism that was not part of the forest was not a part of nature.

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Top of testBase of textFor example, “[Fish, would it have a role in nature?] No. [Why do you say that?] Because

there might not be ponds in the rainforest. Then you can’t have fish if there’s no water”(Y6); (2) Some organisms don’t have a role because people don’t need them. These stu-dents appeared to have the anthropocentric view that a biological role is only significantif it directly supports humans. For example, “[Mushroom, would it have a role in nature?]I don’t think it does because it is a food sometimes we eat, but it wouldn’t be that bad ifwe missed out on it” (Y6); (3) Some organisms don’t have a role because they have nopredators. These students appeared to have the view that the main role of an organism isto provide food for other living things. For example, “[Jellyfish, would it have a role?]Not really, because some jellyfish are poisonous to other animals so they can’t feed offthem.” (Y6).

In summary, among the group 2A students it was possible to identify five alternativeconceptions as to why organisms would not have a role in nature. Each of these had somesignificance within the population because they were each used by two or more individuals,and they each had some significance within the minds of the individuals who expressedthem, because they were applied to two or more of the items on the list. However, thefollowing important point needs to be made. All of the group 2A students also circledsome of the items, indicating that they believed that some of the organisms in the list didhave a role in nature. The students’ reasons for circling the items were examined and itwas found that, like the group 1 students, they described a range of different types ofscientifically acceptable biological roles. For example:

[Worm] I think because the birds eat the worms. If there was no worms then there probablywouldn’t be any birds. (Y6)

[Grass] Just to keep the soil from erosion. (Y6)

[Butterfly] Well it climbs on a flower and goes to another flower and takes pollen with it.(Y6)

[Seaweed] It’s a place for the fish. Like to get away from the sharks. (Y10)

In order to establish whether these students had a scientifically acceptable conceptionof biological role, it was decided to adopt the same criterion as for the alternative concep-tions. That is, if a student was able to clearly describe a scientifically acceptable biologicalrole for two or more of the organisms then they were considered to have such a conception.It was found that 93% of the year 6 students and 89% of the year 10 students who werein group 2A fell into this category. It was therefore concluded that these students had twodifferent types of conceptions about biological role—a scientifically acceptable conceptionand an alternative conception.

The final step in the analysis of the group 2A students was to examine their responsesto the question of how they decided which organisms do or do not have a role in nature.The majority of group 2A students (90% of the year 6 students and 75% of the year 10students) briefly described two roughly opposing ideas (one representing the scientificallyacceptable conception and the other representing the alternative conception), which theyconsidered when choosing. Examples of these are presented in Table 1.

An important feature of these statements was that, when describing the opposing reasons,the students used the same or similar patterns of words, which indicated that they werelooking at two, roughly opposing aspects of the same process or phenomenon (like thetwo sides of a coin). In Table 1, these words are in italics. The implication here is that thetwo opposing ideas were linked in the students’ minds. The other notable feature of these



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Examples of Students’ Reasoning

[How do you decide if something does have a role in nature?] If it does something that’simportant or helpful or stuff like that well it’s got a role. [How do you decide if somethingdoesn’t have a role in nature] If it doesn’t be helpful. (Y6)

[How do you decide that something does have a role in nature?] When other animals orpeople need that other animal to survive. [How do you decide whether something hasn’tgot a role in nature?] If nobody else really needs it and it’s just there really. (Y6)

[How do you decide whether something does have a role in nature?] If it’s food for otheranimals or it helps keep the environment alive. [How do you decide whether somethingdoesn’t have a role in nature?] When they don’t help the environment at all or the for-est. (Y6)

[How did you decide which ones to circle?] I decided the ones to circle that like do some-thing. That don’t just swim or are there. Like they can do something. [How did you de-cide which ones not to circle?] Just the ones that were just lying there and doingnothing to the world. (Y6)

[How do you decide whether something does have a role in nature?] . . . Most of themgrow and do good things to the Earth. [So how do you decide if something doesn’t havea role in nature?] It does bad things to the Earth. (Y6)

[How do you decide that something does have a role in nature?] If it’s to have a role innature it should be of some use to us. [How do you decide whether something doesn’thave a role in nature?] If it’s no great use to us then it shouldn’t be there at all really.(Y10)

[What made you decide not to circle those ones?] Some of them you don’t need, like fliesand mushrooms. The other ones are just pretty boring. [How do you decide whetherthings have got a role in nature?] Most of them like tree and things that we eat and thatwe need. Things that we can use. Things that are good to help. (Y10)

[How do you decide if something does have a role?] Well you think of if what they do isbeneficial to the way we live or any other animals. [How do you decide whether some-thing doesn’t have a role?] If you can’t think of anything that they do. If they don’t doanything at all well they don’t really have a role. (Y10)

statements was that they could be represented in “if . . . then” form. For example, manyof the responses in Table 1 could be paraphrased as, “If an organism does somethingimportant or helpful then it has a role, but if it is not helpful then it does not have a role.”

Group 2B. The students in this group (19% of year 6 and 20% of year 10) could not beplaced in either of the two previous groups. All the primary schools and both high schoolswere represented. Most of these students (57%) circled all of the items except one, andgave at least two scientifically acceptable examples of biological roles. However, theycould not be placed in group 1 because they had not circled all the items, and they couldnot be placed in group 2A because they did not show evidence of an alternative conception(for not having a role) in relation to at least two of the items. Their understandings couldtherefore not be clearly identified according to the criteria adopted for this study. However,there was some evidence that their thinking was comparable to that of the group 2Astudents—several of them did use an alternative conception but on only one occasion

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Top of testBase of text(e.g., “I don’t think germs should have a role in it because they’re not good for you and

they make you sick” [Y6]), and made statements suggesting that the way they chose wassimilar to the group 2A students. For example (italics inserted as done previously):

[How do you decide whether something does have a role in nature?] I think of what theydo and whether it’s actually important or not. [How do you decide whether somethingdoesn’t have a role in nature?] If it doesn’t really do anything. It just does nothing all day.(Y6)

Most of the remaining group 2B students circled some of the items and gave someacceptable examples of biological roles, but their reasons for not circling items could notbe clearly identified, usually because they were not sure, or their reasons were not clear,or a clear reason was given on only one occasion. Finally, two students (including onewho had circled all the items) were in this group because their interviews had to beterminated prematurely.

DISCUSSION

It is possible to make some comparisons between the year 6 and the year 10 studentsin this study although these findings should be treated with care, because, as in any cross-age study, it should not be assumed that the two populations were completely equivalent.The main difference between the two cohorts was that the older students were less affectedby context (only 35% of the year 6 students were in group 1, but 61% of the year 10students were in group 1). This agrees with other studies that have found that older studentsare less influenced by context (Leach et al., 1996; Lowe, 1997).

However, there were also some similarities between the two year levels. Probably themost telling similarity was the disappointingly low number of group 1 students who useda “living things” approach to the task. It might have been hoped that many of the year 10students would have reasoned that all the items in the list were living things so thereforethey must all have roles. However, only a minority of students from both years showedevidence of this. The reasoning used by many other group 1 students appeared to be moretautological—that is, they all have a role in nature because they are all “part of nature.”The apparent unwillingness of these students to utilize the concept of “living things” hasan important implication for high school science—research has shown that most studentsin grades 5–9 can correctly identify plants and animals as living things (Tamir, Gal-Choppin, & Nussinovitz, 1981), but a good understanding of a concept such as “livingand nonliving” does not simply involve a knowledge of which things are classified aswhich. An aspect that is equally important, but that is often neglected, is that studentsshould also clearly understand how to apply this knowledge in relation to other biologicalprinciples.

Another similarity between the two cohorts was that the same five alternative concep-tions were identified among students (in group 2A) from both years. This implies that theyare common ways of thinking in the population, and that they are robust enough to havesurvived schooling. There is also some evidence that at least one of them is of more thanregional importance—Munson (1994) found that North American students had a beliefthat “varying the population of an organism may not affect an ecosystem, because someorganisms are not important” (p. 33). This is very similar to the idea that “some organismsdo not do anything significant, they are just there,” as identified in the present study.

This similarity is disappointing in that it would be hoped that their high school scienceexperiences would have had a more marked effect upon the responses of the year 10



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instructional strategies at high school level. However, an important prerequisite for anysuch strategy is first an understanding of the nature of the students’ reasons for respondingin this way. This issue is discussed in the following section, with reference to the group2A students.

Students’ Reasons for Responding to Context

Group 2A represented 46% of year 6 and 18% of year 10 students. These students (witha small number of exceptions) had both a scientifically acceptable conception and analternative conception, and these two opposing ideas were linked in their minds. Whenasked to describe how they chose which things have a role in nature, the group 2A studentstypically responded with statements that could be summarized in an “if . . . then” form;for instance, “If it does something important or helpful then it has a role, but if it doesn’tdo much, or doesn’t do anything helpful, then it does not have a role.” As Table 1 shows,many of the students did not present their ideas this explicitly and in this exact form (e.g.,a number of them provided responses that were highly anthropocentric), but neverthelessit could be taken as a general representation of the type of statements that they made.

The sort of “if . . . then” statement just described is commonly referred to as a prop-osition, so these types of ideas will be referred to as “personal propositions” in the re-mainder of this study. The significance of the personal proposition is that it is the plan thatthe student uses to decide which conception is the appropriate one to use in any givensituation or context. For example, a student might use a scientifically acceptable conceptionof biological role for some organisms and an alternative conception for other organisms(and may indeed have more than one alternative conception). This interpretation has sev-eral implications, which will now be addressed.

The first implication is that the personal proposition represents a knowledge structure.As stated earlier, it is the plan that the student uses to make decisions about biologicalrole, as it applies to a spectrum of contexts. By using this plan, the student will invoke analternative conception in some contexts and a scientifically acceptable conception in othercontexts. It could therefore be envisaged as being a higher order structure than either ofthese conceptions. In this respect, it could be viewed as being “theory-like” in that it appliesto a wide range of contexts. Driver and Easley (1978) used the term “alternative frame-works” to describe children’s knowledge structures that have developed through theirexperience of the physical world rather than through science education. They also statedthat “many notions children hold are used in a range of situations and have the character-istics of elementary models or theories” (p. 62). Similarly, McCloskey (1983) stated thatmany students had an aristotelian view of motion and that such views represented “ageneral, coherent theory of motion that adequately guides action in many circumstances”(p. 114A). However, these representations of “theory-like” knowledge structures werechiefly used to describe one particular alternative conception that students had, and therange of contexts to which it applied. On the other hand, the personal proposition isqualitatively different because it refers to a structure that allows students to cover a broaderrange of contexts by selecting from a “quiver” of both scientifically acceptable and alter-native conceptions.

A second implication is that the personal proposition is also a way of reasoning. Studentsused an “if . . . then” relationship to describe how they had solved the task with whichthey were presented. A normal “if . . . then” relationship represents basic conditionallogic, and it has been proposed (Lawson, 1992; Paton, 1996) that this type of reasoningis highly influenced by context. Lawson stated that, “the context of the task influences the

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Top of testBase of textinference patterns one employs in its solution, and that the context effect is due to the

extent to which the subject is able to use his or her knowledge of the context to generatealternative hypotheses/antecedent conditions that could lead to the imagined consequent”(p. 970). Similarly, the type of “if . . . then” reasoning that the personal propositionrepresents is highly context-related. For example, a student who is not aware of the im-portance of fly larvae as decomposers may be inclined to reason that flies do not doanything important, therefore they do not have a role. Some of the students’ other state-ments from the present study provided support for this, because they appeared to respondto the circling task by first thinking about what they knew of the biology or habits ofeach organism individually (and then linking this to their personal propositions). For ex-ample:

If I’ve seen it on a show before, like on “Wildscreen” and I’ve seen what it does . . . .(Y6)

I just thought of what I know they have to do and if what they do is important. (Y10)

I pretty much know a bit about every animal and just what they do and how they feed andtheir daily life. (Y10)

A third implication of the personal propositions model is that it provides a possibleexplanation for students’ inconsistencies in science. It has regularly been observed thatstudents will use one idea in some contexts and another idea in other contexts (EngelClough & Wood-Robinson, 1985; Kargbo et al., 1980; Strommen, 1995) and will thereforeappear to an observer to be inconsistent. However, it has been suggested that students suchas these are being consistent from their own point of view, if not from that of a scientist(Bar, Zinn, Goldmuntz, & Sneider, 1994; Chi & Slotta, 1993; Minstrell, 1992; Watson etal., 1997). The personal propositions model helps to explain how this could happen—from the point of view of the student, there will be no inconsistency because the responseswill be a true reflection of the “if . . . then” nature of their understanding. This lack ofinconsistency from the student’s point of view may explain why such patterns of incon-sistent responses can persist right through to the tertiary level (Brumby, 1984; Haidar,1997; Halloun & Hestenes, 1985).

A fourth implication of the personal propositions model is that it identifies an importantlimitation of “alternative conceptions.” If a student’s understanding of a concept encom-passes a scientifically acceptable conception, an alternative conception, and a personalproposition, it would then be highly misleading to concentrate our attention solely on thealternative conception, because this would ignore a significant part of their total under-standing of the concept. Much of the research that has identified alternative conceptions(or misconceptions) has been carried out because we believe that students’ conceptionsrepresent their ways of making sense of the world (Osborne & Wittrock, 1983). However,if we focus only on their scientifically incorrect conceptions, then we may be producinga very unbalanced interpretation of their understanding of the world around them. It istherefore important that we take into account both their scientific and their nonscientificunderstandings and attempt to describe any relationship that may exist between them.

A fifth implication is that the students’ everyday knowledge and their formal scienceknowledge may not be as strongly separated into two separate cultures of thinking as haspreviously been described (e.g., Hawkins & Pea, 1987). Many of the scientifically ac-ceptable ideas that the students proposed in the present study could easily have had theirsource in the science classroom. For example, all of the group 2A students circled the item



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Top of textBase of text“tree” and one of the most common reasons was because it produces oxygen. For example,

one student stated that trees have a role in nature “because carbon dioxide goes in andoxygen comes out, so if there weren’t any trees then we wouldn’t be able to live.” Inaddition, some students stated that the role of flies was to spread disease, and the role ofbutterflies was to pollinate flowers. It could be argued that these types of understandingsare very difficult to arrive at through everyday life experiences, so they are likely to bethe result of classroom instruction. If this is the case then it could be concluded that theirformal science learning is in fact closely linked to their everyday knowledge, via thepersonal proposition.

Finally, the model also has an important implication for conceptual change. A numberof studies have reported limited success in changing students’ alternative conceptions(Clement, 1982; Gunstone, Champagne, & Klopfer, 1981; Thijs, 1992). One possible ex-planation for this is that the conceptual change experiences are targeted at the alternativeconception, which is often closely related to specific contexts, so any learning that occursmay not transfer easily to other contexts. However, the personal proposition represents a“higher” structure in the students’ minds, because it is the plan that the student uses todecide whether to apply the alternative conception or the scientifically acceptable concep-tion. It is therefore possible that conceptual change strategies may be more successful ifthey are targeted at the personal proposition level of the students’ understanding (e.g., byinitially making students aware of their own personal propositions as well as their con-ceptions). It is interesting that bridging analogies, which concentrate on the link betweenstudents’ anchoring conceptions and their alternative conceptions, have been very suc-cessful (Brown, 1992).

Future Directions

The results of the present study suggest that the use of a simple word list can be a veryeffective technique for eliciting students’ knowledge fragments. It also has the methodo-logical advantage of being systematic—a prescribed range of contexts can be presentedin such a way that other possible variables can be reduced to a minimum. However, thesimplicity of this technique may also be a disadvantage. This type of relatively simple andhighly structured task may have allowed a relatively structured response compared to thetypes of responses that can be obtained from a series of more complex problems, eachwith several contextual variables to which students might respond. It could in fact beargued that the use of an item list may be rather simplistic when we are trying to identifypatterns of students’ ideas in complex, real life situations. There is clearly a need forcomplementary studies to focus on this issue.

Finally, the importance of studying how students generalize their conceptions cannotbe underestimated. One of the aims of science education is that students will develop theirunderstandings of the world around them. Yet this will not be achieved if they are unableto accurately apply scientific principles to the range of everyday phenomena that make upthe world around them. The challenge for science educators is to identify the factors thatinhibit students from doing this, so they may be addressed in the classroom.

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exploring the link between students' scientific and nonscientific conceptions

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