Learning and Instruction 11 (2001) 241–257
www.elsevier.com/locate/learninstruc
Improving conceptual change concerning
photosynthesis through text design
Mirjamaija Mikkilä-Erdmann
*
Department of Education, University of Turku, Fin- 20014, Turku, Finland
Accepted 3 October 2000
Abstract
The purpose of this study was to investigate the effect of text design on 5th grade learners’
comprehension of photosynthesis. The study was theoretically motivated by the recent research
on conceptual change and on text comprehension. Two hundred and nine primary school pupils
(10-11 yr old) studied either a traditional text version about photosynthesis or a conceptual
change text in a classroom situation. The conceptual change text design took common misconceptions about photosynthesis into account and tried to foster metaconceptual awareness. Children who studied the conceptual change text design performed statistically better than the
traditional text group on questions which demanded construction of an adequate mental model
of photosynthesis.  2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
This study examined the effect of text design on conceptual change concerning
photosynthesis. Photosynthesis is a central concept in biology instruction and one
of the topics the research on conceptual change has dealt with. During recent years,
the research on conceptual change has helped us to understand the basic problems
of conceptual development: there are descriptions of pre- and post-change knowledge
that children have acquired at different ages and in different subject domains. There
are, however, few studies which yield information that is applicable in designing
instruction to facilitate conceptual change in science lessons (Hatano & Inagaki,
1997; Vosniadou & Schnotz, 1997).
* Tel.: +358-2-333-88-33; fax: +358-2-333-88-30.
E-mail address: [email protected] (M. Mikkilä-Erdmann).
0959-4752/01/$ - see front matter  2001 Elsevier Science Ltd. All rights reserved.
PII: S 0 9 5 9 - 4 7 5 2 ( 0 0 ) 0 0 0 4 1 - 4
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According to recent research on conceptual development, it is obvious that, already
at an early age, children have more or less coherent systems of knowledge constructed from everyday experience. These systems of knowledge consist of concepts
which are embedded in theories. Vosniadou (1994, p.46) makes a distinction between
a framework theory and a specific theory. A framework theory consists of principles
of categorisation and modes of reasoning which will provide a general description
of the target domain. A specific theory includes more restricted explanations concerning the target domain and is constrained by the framework theory.
Conceptual change can be seen as a specific form of learning, a process of restructuring domain-specific knowledge. According to Vosniadou (1994, p. 46), the simplest form of conceptual change is called enrichment. In the process of enrichment,
a learner is adding new information to an existing theoretical explanation on the
level of specific theories, without changing the framework theory. In the terminology
of Rumelhart and Norman (1978), this kind of learning through accretion, can be
seen as normal, daily accumulation of information. There are no structural changes
in the information-processing system itself but an accumulation of facts about the
topic under study (Rumelhart & Norman, 1978, p. 38).
When the reorganisation of the knowledge structures occurs on the level of the
framework theory it is called revision, and can be considered the most difficult and
significant type of conceptual change, which often requires systematic instruction
(see also Chinn & Brewer, 1993; Vosniadou & Schnotz, 1997; Hatano & Inagaki,
1997). According to Rumelhart and Norman (1978, p.38), this kind of restructuring
of the organisational structures at times seems to be accompanied by a “click of
comprehension”, a strong feeling for the topic that makes a large body of previously
acquired (but ill-structured) knowledge fit into place. This kind of restructuring process involves considerable time and effort, and there is still little evidence how the
process occurs (Rumelhart & Norman, 1978, pp. 39-40).
The problem in the school setting is that children are usually not aware of this
previously acquired knowledge and, its contradictions with scientific knowledge.
Learners tend to enrich their naive representations rather than revise them. They
have partly tested and confirmed their specific theories in an everyday setting where
they appear to work, and see no need to change their framework theories. In these
cases, preinstructional knowledge often functions as a constraint in learning scientific
concepts (Roth, Anderson, & Smith, 1987; Roth, 1990; Glynn & Duit, 1995;
Limon & Carretero, 1997).
When learning about the origin of the Earth, for example, the students in the study
done by Limon and Carretero (1997, p. 223) were partially aware of contradictions
in their knowledge systems but were not able to integrate the data into a coherent
and complete explanation. The younger they were, the less they were aware of contradiction when presented with anomalous and confirmatory data (Limon & Carretero, 1997, p. 221). Upper secondary school pupils’ learning of the Darwinian explanation of evolution also resulted in explanations which were partly incompatible with
the Darwinian one. Learners acquired lot of facts and added new explanations to the
representations they already had, but were not able to apply them in solving problems
(Caravita & Hallden 1994, p. 105).
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Like the theory of evolution, photosynthesis is a concept which is incompatible
with everyday notions. Most children have the misconception that a plant eats, i.e. it
has multiple external sources of food. After instruction about photosynthesis, children
reveal in their explanations that they have learned the concept on the superficial level
through accretion, and can usually label it. But when they are asked to explain it,
their explanations reveal that they assimilate the new notion into the old schema and
think that food for plants can be sun, rain, light, soil plus minerals etc. (Roth, 1990;
Mikkilä, 1997).
Photosynthesis seems to be a concept which it is not possible to learn through
either enrichment or induction in a situated learning setting (see Roth et al., 1997;
Ohlsson and Lehtinen, 1997). The old naive and human-centred notion of food has
to be revised so that it includes the critical distinction between energy-containing
substances (which can only be made by plants through photosynthesis) and other
kinds of nutriments that support life but do not provide energy.
Pedagogical practice, including textbooks, does not normally take the above-mentioned problem of dysfunctional prior knowledge into account. Textbooks often strive
for enrichment and suggest that what learners already know is compatible with scientific knowledge (see Roth, 1990; Mikkilä & Olkinuora, 1994). Until now there have
been few tools to cope with this problem. Presenting a cognitive conflict in the
learning situation has been used as a method by science teachers, but it does not
seem to be enough for promoting conceptual change in a radical sense in young
learners (Caravita & Hallden, 1994, p. 95; Limon & Carretero, 1997, p. 218).
Textbooks are used as the dominant method even in science instruction (Guzzetti,
Snyder, & Glass, 1992; Stinner, 1995). They can be seen as an unexplored resource
in promoting higher order conceptual understanding. However, a still more or less
unanswered question is what type of text could promote conceptual change in relation
to scientific topics.
Wang and Andre (1991) investigated the effect of a text-they call it a “conceptual
change text”-on the understanding of electrical circuits. They constructed a text
which consisted of a traditional non-refutational text into which a series of diagrams
of electrical circuits designed to elicit students’ common misconceptions were
inserted. The purpose of their conceptual change text design was to activate the
students’ existing schemata-through diagrams and questions on whether they would
work-and then provide information countering the misconceptions. Subjects who
received the “conceptual change text” significantly improved their performance
(Wang & Andre, 1991, p. 113).
In the study of Wang and Andre (1991) the text was still to a large extent a
traditional expository text. Hence, it is difficult to determine whether the text actually
had an effect on learning or whether the learning was to a large extent gained through
the diagrams which were inserted in the text. However, other studies reported briefly
below, gave us ideas with which to develop the conceptual change text design used
in this study.
Guzzetti et al. (1992) conducted a meta-analysis to find a type of text which has
been proved to foster conceptual change. Although the results are partly contradictory, a refutational text which attempted to create a cognitive conflict and explain
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why the naive conception is incorrect seemed to be more effective in facilitating
conceptual change than a traditional expository text (Guzzetti et al., 1992, p. 647).
The studies of Guzzetti et al. (1992) and also of Wang and Andre (1991) deal
with older students who seem to profit from the “conceptual change sections”. But
among young learners, a text which causes discomfort and then explains the correct
way to understand the phenomenon is perhaps not a sufficient aid. Young learners
are not aware of the hypothetical nature of their explanatory frameworks. It can be
expected that if the specific theory of the learner is wrong, then the experience of
cognitive conflict does not give enough support for revision of the framework theory.
The student may learn that his or her specific beliefs are wrong but does not understand why because his or her naive theory seems to work in everyday life (see
Limon & Carretero, 1997, p. 218; Vosniadou & Ioannides, 1998).
Text comprehension is a flexible strategic process: readers adapt their cognitive
processing to specific aims in order to construct different types of mental representations (Schnotz, 1993, p. 114). The representations of text are formed by drawing
connections between both outside knowledge, i.e. preinstructional knowledge, and
the information given in the text. According to van Dijk and Kintsch (1983), the
reader constructs a propositional representation (text base) and a mental model
(situation model). In this construction process, the text loses its “individuality”
(Kintsch, 1988, p. 163), because text knowledge and prior knowledge are integrated
in order to create a global meaning, a mental model. There is evidence that if the
reader fails to bring his /her knowledge to bear on the text, or if features of the text
inhibit the reader from making connections between outside knowledge and text
information, comprehension, i.e. construction of a mental model, may be impeded
(Beck, McKeown, Sinatra, & Loxterman, 1991, p. 254). Construction of the mental
model of the text can be considered the very criterion of text comprehension
(Kintsch, 1986).
A study done by Alevermann and Hague (1989) provided a very interesting contribution for dealing with the problem of dysfunctional prior knowledge through text
design. This study examined the effects of activating prior knowledge and refutation
text structure on students’ comprehension of counterintuitive science material. It was
found that students benefit from a text that explicitly points out incongruences
between the students’ thinking and the ideas expressed in the text: “If you thought
that the path the marble would take would be…., your ideas may be different from
what the laws of physics would suggest. As you read the following text, be sure to
pay attention to those ideas presented in the text that may be different from your
own.”. Alevermann and Hague (1989, p. 198) call this approach augmented activation, i.e. advance “warning” of possible inconsistencies between the reader’s
beliefs and information in the text. It was suggested that once the incongruences
were pointed out, students would be more likely to modify or correct their misconceptions. This suggestion was confirmed by their findings (Alevermann & Hague,
1989, p. 200).
For a learner, the process of becoming aware of a possible mismatch between
his/her ideas and science contents to be learned through a text could be an essential
factor in promoting metaconceptual awareness. Metaconceptual awareness can be
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seen as recognition of the differences between naive and scientific representations.
This can be seen as an important prerequisite for conceptual change (see Vosniadou,
1994, p. 67; Vosniadou & Ioannides, 1998, p. 1224). In the present study, it is
suggested that text characteristics which stimulate metaconceptual awareness could
be an even more crucial factor in promoting conceptual change than other text qualities, such as organisational coherence or explanatory style which has been shown
to support learning from a text among, e.g. low prior knowledge learners (Beck et al.,
1991; Schnotz, 1993; McNamara, Kintsch, Songer, & Kintsch, 1996). The conceptual
change text design is introduced through what is referred to as a refutational text
which systematically tries to point out the differences between students’ preinstructional thinking and scientific notions.
In sum, the purpose of the present study was to investigate how text design, which
systematically attempts to foster metaconceptual awareness by directly pointing out
that learners’ previous ideas may differ from those expressed in the text, promotes
conceptual change. It is suggested that conceptual change text design can assist a
learner in revising prior conceptions and enable him or her to construct more appropriate mental models of photosynthesis.
The following research questions were addressed:
1. Does a text design which systematically attempts to foster metaconceptual awareness improve conceptual change concerning photosynthesis?
2. How do learners with different levels of prior knowledge benefit from a conceptual
change text design?
2. Method
2.1. Participants
The participants were 209 school pupils 10-11 yr of age from five primary schools
which were located in urban and socio-economically different areas. The children
were randomly assigned to two experimental conditions.
2.2. Materials
Two versions of texts about photosynthesis were used in the experiment. The
versions had the same content but were organised in two different ways: A traditional
text (TT) and a conceptual change text (CT). The traditional text was taken from a
contemporary science textbook widely used in schools (Aho, Enqvist, Kytömäki,
Nurmi, & Saarivuori, 1995). It is the best current school text on photosynthesis
available: coherent and explanatory. The conceptual change text was prepared for
the experiment. Because of the extended explanations throughout the metaconceptual
text, the conceptual change text (597 words) was slightly longer than the traditional
text (441 words) (see Appendix A and Appendix B).
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The main differences in the two versions of text are as follows: (a) macro-level
organisation and (b) textual units inducing metaconceptual awareness.
(a) Macro-level organisation. Traditional text does not take the common misconception of the role of water into account (“water is food”=energy-containing
substance for a plant) but aims to enrich learners’ prior knowledge and starts from
a description of the importance and function of water in the plant. It follows the
thematic pattern: a plant needs water; water goes into the plant along tubes; explanation of photosynthesis; self-sufficient/other-sufficient; the global importance of
photosynthesis (see Appendix A for a complete copy of the traditional text).
The conceptual change text design takes the critical difference in the production
of energy as its starting point: (“Plants and animals need energy to live”…“Plants
differ from all other living organisms because they can make their food by
themselves.”) Thus, the conceptual change text design tries to produce a cognitive
conflict with the children’s alternative conceptions. It contrasts the learners’ prior
knowledge with the scientific knowledge from the beginning to the end of the
text. Its thematic structure is as follows: all living organisms need energy; plants
produce their own food; self-sufficient/other-sufficient; explanation of photosynthesis; self-produced sugar is stored; the global importance of photosynthesis (see
Appendix B).
(b) Text elements inducing metaconceptual awareness. A significant difference
between the traditional text and the conceptual change text is that the former has
no metaconceptual content. The metaconceptual text content directly points out
the difference between possible misconceptions of the learner and the scientific
thinking concerning photosynthesis. The metaconceptual text tries to keep the
reader on the right path to construct an adequate mental model of the phenomenon.
In the conceptual change text, there are seven metaconceptual text elements
such as, “How plants get their food happens in a different way than we normally
think. How does the energy get into a plant? Is water food for a plant?”… “It is
important to understand that a plant does not take ready-made food through its
roots from the soil. So a plant does not eat but makes its food in the chloroplasts…”. “Thus, water is not food for a plant but only one of the raw materials
it uses to make its own food in the process called photosynthesis.” “Food chains
help us to understand how energy circulates in nature.” “It is important to learn
that plants can make their food by photosynthesis and do not take it in through
their roots from the soil.” “When you are learning about photosynthesis it is useful
to think of the difference which exists between plants and animals concerning
how they get their food.” “The most important thing to understand about photosynthesis is that only plants can absorb light energy for food and produce oxygen
as a by-product” (see Appendix B for a complete copy of the conceptual
change text).
2.3. Pretest-posttest questions
Conceptual change test was measured by the use of 11 open-ended essay-type
questions which can be categorised as follows: (1) Retention questions requiring fact
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finding: the answers were explicitly stated in the text (n=2) (e.g. What are tubes?);
(2) Inferential text comprehension questions also based on the text demanding understanding of essential subelements of the concept photosynthesis (n=2) (e.g. What are
chloroplasts?); (3) Critical distinction questions (see Hatano & Inagaki, 1997) requiring understanding of the basic ontological distinction between animals and plants (
n=4) (e.g. What does a plant/human being need to live and grow? Where does it
come from?); (4) Generative questions (see Vosniadou, 1994) requiring the learner
to solve a novel problem by constructing an adequate mental model of photosynthesis
(n=3) (e.g. When we eat a potato, we get energy. How does the energy get into the
potato?). Both retention and inferential text comprehension questions were targeted
to measure comprehension on the text-base level. Critical distinction questions and
generative questions tried to tap into the mental model construction and thus they
can be used as criteria for conceptual change.
2.3.1. Scoring
In order to compare the performance on the conceptual change test by participants
who read traditional text versions and participants who read conceptual change text
versions, a template of model answers based on the data was developed. The first
step in the development of model answers was that two raters read the tests through
and negotiated the following scores for different question types:
1. Retention questions were scored 0-3. Three credits were given if the fact asked
about in the question was given correctly. Two credits were given if the answer
consisted of relevant information but was not exact enough. One credit was given
if the learner produced an isolated piece of information. In the scoring of every
question type zero means no answer was given by the learner.
2. Inferential text comprehension questions were scored on a scale 0-5 because this
corresponded better with the nature of the data and worked well. The highest
score (5) was given if the learner produced a text-based explanation of photosynthesis. Four credits were given if the participant produced an almost perfect explanation of the process but made a few mistakes. Three credits were scored for an
answer which only explained the end result of photosynthesis. Two credits were
given when the answer revealed that the learner had understood part of the process. One credit was given for an isolated fact.
3. Critical distinction questions were scored on a scale 0-5. Five credits were given
if the learner understood that plants are self-sufficient. Four credits were given if
the end products of photosynthesis were mentioned in the answer. Three credits
were given if the answer consisted of a morphological definition of a plant. Two
credits were given if the answer showed that the difference between plant and
animal was partly understood, partly not. One credit was given for answers which
suggested that a plant takes its food from the soil. Furthermore, three of the critical
distinction questions were scored 0-3. Three credits were given if the pupil understood the differences between plants and animals in the production of energy.
Two credits were given if the learner produced an answer which revealed that
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he/she thought a plant gets its food both from the soil and from the sun. One
credit was given for an explanation consisting of isolated facts.
4. One generative question was scored 0-5 (see critical distinction questions). Two
generative questions were scored 0-3. The highest score (3) was given if the
answer revealed an appropriate mental model of photosynthesis. Because of the
open-ended nature of the questions, every paper was read by two raters and the
interrater agreement on scoring was calculated. Interrater agreement on answers
was 0.94. Disagreements were settled through negotiations.
2.4. Procedure
The empirical phase of the study took place during two weeks. Both the pretest
and the posttest were conducted separately in a classroom situation. The measures
used in the pre- and posttest were exactly the same. In the first session, the learners
were given a pretest which they did in their classroom. They had one hour time to
answer the questions. In the second session the following week, the intervention took
place, the pupils being randomly given one of the text versions and a conceptual
change posttest. They were then instructed to study the text as they normally do
when working on their assignments. It was possible for them to make use of the
text while answering the questions in the posttest. Children were told that the target
of the learning is not memorising but understanding. There was no time limit, but
it took approximately one hour in both treatment groups to read the text and do the
assignments. The treatment groups were as follows:
1. Traditional text design group (n=98)
2. Conceptual change text design group (n=103)
3. Results
3.1. Pretest knowledge
A t-test was performed for every question type, and the results show that there
were no statistically significant differences in the quality of prior knowledge between
treatment groups in the pretest.
3.2. Retention and inferential text comprehension questions
In the following, sum scores of every question type are used in the analyses.
First, an ANOVA (repeated measures design) was performed for each question
type including between-subjects factor of text design and within-subjects factor of
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Table 1
Means and standard deviations of every question type as a function text design
Question type
Traditional text design
(n=98)
Conceptual change design
(n=103)
Retention questions
(min=0, max=6)
Inferential text questions
(min=0, max=10)
Critical distinction questions
(min=0, max=14)
Generative questions
(min=0, max=14)
M=4,7
SD=1,2
M=6,2
SD=2,3
M=8,9
SD=2,1
M=6,7
SD=2,0
M=4,2
SD=1,4
M=6,9
SD=2,4
M=10,5
SD=2,4
M=7,4
SD=2,2
test (pretest-posttest). Means and standard deviations of each question type are
presented in Table 1.
Retention and inferential text questions attempted to measure text-based comprehension about photosynthesis. Both retention and inferential text comprehension
answers improved significantly from pretest to posttest, F(1,199)=97.8; P⬍0.001; F
(1,199)=280.6; P⬍0.001. However, there were no interaction effects (text
design×pretest-posttest) on retention questions or on inferential text comprehension
questions (see Figs. 1 and 2).
Second, an ANCOVA was performed with the prettest as a covariate for the posttest performance on retention questions and on inferential questions. On retention
Fig. 1.
Performance on retention questions.
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Fig. 2.
Performance on inferential text comprehension questions.
questions, a significant main effect for treatment was obtained favouring the traditional text design group, F(1,198)=6,63; P⬍0.05. The ANCOVA showed no significant treatment effect for the posttest performance on inferential text comprehension questions.
Furthermore, in order to test how children with low/high scores in the pretest
(median-split) benefited from conceptual change text design, a two-way ANOVA
was performed on each question type including between-subjects factors of text
design and of low/high performance scores in the pretest. On retention questions, a
main effect was obtained for text design, F(1,197)=4,85; P⬍0.05. There was also a
significant main effect for level of prior knowledge, F(1,197)=9,93; P⬍0.001, but
no interaction effects were observed. The post hoc test (LSD) revealed, at the 0.05
level of significance, that on retention questions, the traditional text design was more
effective for the low prior knowledge learners (M=4,42) than the conceptual change
text design (M =3,84). In sum, the traditional text design seems to support better
fact-finding in low prior knowledge learners than the conceptual change text design.
However, on the inferential text comprehension questions, which also required
understanding and inferencing at the text-base level, the ANOVA revealed interesting
main effects for text design, F(1,197)=4,60; P⬍0.05, and for level of prior knowledge, F(1,197)=8,59; P⬍0.05. There was also a significant interaction effect (text
design×levels of prior knowledge) on inferential text comprehension questions, F
(1,197)=5,23; P⬍0.05, favouring the high prior knowledge learners in the conceptual
change group (M=7,78) compared to the high prior knowledge learners in the traditional text design group (M=6,30). In sum, the high prior knowledge learners profited from conceptual change text design in questions which were constructed to
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measure inferential text comprehension. However, we obtained no effect of text
design on inferential questions in learners with lower scores in the pretest.
3.3. Critical distinction questions
In the critical distinction questions, which measured the understanding of the ontological distinction between plants and animals, the text design seems to play an
important role. The change in the critical distinction questions from pretest to posttest
was statistically significant in all treatment groups, F(1,199)=218.3; P⬍0.001. Furthermore, there was a strong interaction effect (text design×pretest-pos-test
performance) favouring the conceptual change design group which scored from pretest to posttest significantly better in critical distinction questions, F(1,199)=27.1,
P⬍0.001, than the traditional text design group (Fig. 3).
A one-way ANCOVA was performed with the pretest as a covariate for the posttest performance on critical distinction questions. The above-mentioned tendencies
were confirmed. There was a strong treatment effect favouring the conceptual change
group, F(1,198)=32,8; P⬍0.001.
Furthermore, a two-way ANOVA was performed (text design×high/low pretest
knowledge) on critical questions. The results show strong main effects for text
design, F(1,197)=29,78; P⬍0.001, and for level of prior knowledge F
(1,197)=13,33; P⬍0.001. But no interaction effects were gained. However, the post
hoc test (LSD) resulted in significant differences (P⬍0.05) between low prior knowledge learners in the traditional design group (M=8,4) and in the conceptual change
design group (M=9,80). Also the high prior knowledge learners in the conceptual
Fig. 3. Performance on critical distinction questions.
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change text group (M=11,27) outperformed the high prior knowledge subjects in the
traditional text design group (M=9,23). In sum, both low and high prior knowledge
subjects benefited from the conceptual change text design in answering the critical
distinction questions.
3.4. Generative questions
The generative questions attempted to measure the construction of a mental model
of photosynthesis. Both treatment groups performed significantly better from pretest
to posttest in generative questions, F(1,199)=82.3; P⬍0.001. Furthermore, there was
a strong interaction effect for text design and for pretest-posttest performance, F
(1,199)=11.65; P⬍0.001. The subjects in the conceptual change group improved
significantly more on the generative questions than did the subjects in the traditional
text design group (see Fig. 4). The ANCOVA confirmed the results.
A two-way ANOVA (text design×high vs. low prior knowledge in the pretest) on
generative questions produced significant main effects for text design, F
(1,197)=9,24); P⬍0.05, and for the level of prior knowledge in the pretest, F
(1,197)=20,39; P⬍0.001. The post hoc test LSD showed significant differences
(P⬍0.05) between treatment groups in favour of conceptual change design: low prior
knowledge learners (M=6,78) in the conceptual change design group performed better
on the generative questions than low prior knowledge learners in the traditional text
design group (M=5,85). Also higher pretest score subjects benefited from the conceptual change text design (M=8,07) compared to learners with higher pretest scores in
the traditional text design (M=7,2). In sum, both low pretest score learners and high
Fig. 4.
Performance on generative questions.
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pretest score learners profited from the conceptual change text design when measured
by generative questions which required construction of a mental model of photosynthesis and can thus be considered as a criterion for conceptual change.
4. Discussion
The results of this study indicate that the used conceptual change text design
helped the learners to go through the conceptual change concerning photosynthesis.
The traditional text version worked well in questions which are typical “school questions” requiring fact-finding and text comprehension mainly on the level of the text
base. But if conceptual change is measured by questions which first presuppose
understanding of the critical difference between a plant and an animal and, second,
also demand construction of an adequate mental model of photosynthesis, the conceptual change design was significantly better.
The main results of this study encourage optimism about the possibility of designing a science text to promote conceptual change. Although textbooks are still widely
used as the main source of science instruction, most interventions are intended to
promote conceptual change in a classroom setting have not dealt with textbooks but
have required a lot of resources, e.g. time and teacher-student interaction. The textbook as a tool for conceptual change has so far been neglected. According to the
results of this study, it is possible to produce a significant change in children’s understanding of one important concept in science with a relatively easy and economical
investment in the design of a conceptual change text design. Even with low prior
knowledge, learners seem to profit from a conceptual change text design.
In general, it seems to be important to pay attention to possible misconceptions
in the specific domain when starting to design a science school text. A manual for
textbook writers about misconceptions in a specific field might be relevant. Until
now the commercial publishing houses have mainly determined the guidelines for
developing textbook designs for science instruction. One way to render the dissemination of the findings of the research on conceptual change more effective is to
develop a handbook for teachers as well. Thus, the research on conceptual change
could inform current textbook production and hence development of educational
practice.
The findings described here leave some research questions to be investigated in
future studies. First, how long lasting and stable are the conceptual changes generated? It may be that although the effects of the conceptual change design were very
strong, the shift back to the old ways of thinking will often take place without further
systematic instruction. A delayed test would give us an answer to this question.
Secondly, the interaction between levels of text comprehension and conceptual
change is an interesting question for future studies. It could be suggested that good
readers may experience conceptual change through the text more easily than less
competent readers. On the other hand, not so high-achieving readers who proceed
mainly “bottom-up” may perhaps profit more than high-achieving readers from the
metaconceptual text and achieve better learning results with a conceptual change
design than with a traditional text design.
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Thirdly, the effect of text design on conceptual change could also be related to
the text comprehension process. It would be interesting to compare the text versions
sentence by sentence and investigate how text comprehension proceeds on-line.
There may be critical moments, for example, at the beginning of the text in which
a construction path for an inadequate mental model can be activated through an
example which provokes misconceptions: “you can think how the water goes from
the roots up to the plant” or there can also be misleading analogies in the text such
as “photosynthesis is like a factory”, which lead to the conception that photosynthesis
is a matter and not a process, etc. On the other hand, the metaconceptual text, which
directly points out the differences between learners’ thinking and scientific thinking,
could put the reader again back on the right track.
Fourthly, the role of pictures also needs to be investigated. Pictures may be able
to support adequate mental model building and facilitate conceptual change if they
are integrated into the text through references and legends or when the topicalisation
in the pictures runs paralel to the text. Multimedia learning environments will also
offer new possibilities for designing more effective methods to investigate conceptual
change and to create more effective learning environments in order to promote conceptual change in the classroom setting. Finally, the main target of future studies is
to look for new ways to promote metaconceptual awareness.
Appendix A. Traditional text design
A.1. Photosynthesis
A plant needs water to live and gets the water from the soil through its roots. At
the same time it gets nutrients which are dissolved in the water and which the plant
needs, besides the water, to grow its new cells. You can follow the path of the water
in a flower if you dye the water in a glass jar.
A.2. Where does the water go in a plant?
If you cut the stem of the flower along its length in the coloured water, you will
notice that the colour is not even. In the stem you can see little dyed dots. In these
dyed places you can see, side by side, thin pipes. In these pipes, water is going
through the roots to the stems and to the leaves.
Water goes through the roots to the leaves as a continuous water stream. In the
leaves there are little openings (stomata) from which the water steam evaporates all
the time in warm conditions. From the soil, new water is absorbed all the time in
the place of the evaporated water. The water evaporates but the nutrients from the
water remain in the plant.
A.3. Work within a leaf
A plant emerges, grows, develops and eventually dies like all other organisms.
However, all plants make their building materials and their food by themselves,
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unlike the other organisms. The process by which a green plant makes its food is
called photosynthesis.
In photosynthesis a plant needs as raw materials water and nutrients. From the
air the plant gets, through air openings, carbon dioxide which is needed in photosynthesis.
There are chloroplasts in the leaves of the plants which have a green colour substance called chlorophyll. In the chloroplasts, carbon dioxide and water are made into
sugar with the energy from the sun.
As a plant photosynthesises, at the same time oxygen is released. Oxygen goes
from the leaves, through air openings, to the atmosphere. All the oxygen which is
in the air comes from plants.
A.4. Photosynthesis
앫
앫
앫
앫
앫
A factory: the chlorophyll of the plants
Raw materials: water with its nutrients and carbon dioxide
Energy: sun energy
Products: sugar and oxygen
A plant is self-sufficient for food unlike animals which are other-sufficient, dependent on other organisms for food. These concepts refer to an organism that survives without another organism. Plants do survive, animals do not. A plant makes
its own food, whereas animals get their food from other organisms, plants and animals.
앫 A human being can do almost everything but not photosynthesise in laboratory
conditions. All the food resources and oxygen in the world are originally produced
by the plants.
Appendix B. Conceptual change text design
B.1. Photosynthesis
Plants and animals need energy to live and this comes from food. How plants get
their food happens in a different way than we normally think. How does the energy
get into a plant? Is water food for a plant?
B.2. Plants make their own nourishment
Plants differ from all other organisms because they make their food by themselves.
Plants can absorb the light energy from the sun which goes into food. It is important
to understand that a plant does not take the ready-made food through its roots from
the soil. So a plant does not eat but makes its food in the chloroplasts which are
mostly in the leaves. Thus water is not food for a plant but only one of the raw
materials it uses to make its own food in the process called photosynthesis.
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Green plants are self-sufficient because they can absorb the sun light into the food,
and they do not need any other organisms to survive. Animals, like a human being,
are other-sufficient, because they get the energy they need from the plants. All the
energy in our food comes from the plants. We get energy either through eating plants
or through animals which have eaten plants.
Food chains help us to understand how energy circulates in nature. A wolf gets
energy through eating a rabbit which has got its energy from the grass, and the grass
has got its energy form the sun. Energy comes into the food chain only through
plants. It is important to learn that plants can make their food by photosynthesis and
do not take it in through their roots from the soil.
B.3. Where and how does the photosynthesis happen?
When making food, i.e. in photosynthesis, a plant absorbs light energy which goes
into the food. When you are learning about photosynthesis, it is useful to think of
the difference which exists between plants and animals concerning how they get their
food. Plants make their food by themselves, but animals eat food made by plants.
A plant needs raw materials for photosynthesis: carbon dioxide from the air and
water from the soil. Water goes through pipes in the roots up the leaves. The end
products of photosynthesis are sugar and oxygen. Sunlight energy is used as driving
force. The chloroplasts convert water and carbon dioxide with the help of sun energy.
Thus, this process is called photosynthesis (photo means light in the word). As a
result, oxygen is produced, which is released into the air through the openings
(stomata) in the leaves. Hence plants make their food by themselves in the chloroplasts which are in the leaves. The green colour of the plants is caused by a colour
substance chlorophyll.
B.4. Where do the plants store the self-produced sugar?
The end product of photosynthesis is sugar which is plants’ food. A plant does
not use all the sugar immediately but changes it to other nutrients which are easier
to store. So fruit sugar and sugar combined with proteins circulates to the fruits,
seeds and nuts. When we eat that food we get the energy we need to live.
B.5. Photosynthesis as a basis for life
The most important thing to understand about photosynthesis is that only plants
can absorb light energy in food and produce oxygen as a by-product. Photosynthesis
is the most important factor in helping the world survive, because only green plants
can make use of light energy from the sun when making food through photosynthesis.
Without plants there would be no food and no oxygen in the world. Thus, all animals
are dependent on plants.
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