DIAGNOSING STUDENTS' UNDERSTANDING OF ENERGY AND ITS ...

VIVIEN MWEENE CHABALENGULA, MARTIE SANDERS and FRACKSON MUMBA

DIAGNOSING STUDENTS’ UNDERSTANDING OF ENERGY AND ITS RELATED CONCEPTS IN BIOLOGICAL CONTEXT Received: 1 June 2010; Accepted: 16 February 2011

ABSTRACT. This study diagnosed the understanding about energy and biologicalcontext energy concepts held by 90 first-year South African university biology students. In particular, students’ explanations of energy in a biological context, how energy is involved in different biological situations and whether energy is present and what types of energy are involved in diagrams depicting biological phenomena were investigated. The pencil-and-paper diagnostic test, specifically designed for this study, was used to elicit students’ understanding using test items involving biological phenomena. The results showed that many students had problems in understanding energy and energy-related concepts in the following areas: First, the majority of the students provided definitions of energy rather than the explanations they were asked to provide, and the definition could have been rote-learned. Second, although nearly all students knew the energy conservation principle (energy cannot be created or destroyed), many of them were unable to apply this concept to biological contexts. Third, many students erroneously claimed that the energy for metabolism and life processes is made available during photosynthesis in plants, during digestion in animals or that this energy comes directly from the sun. Fourth, about two thirds of the students erroneously indicated that there is no energy involved/present in inanimate objects such as a statue. The implications for the teaching and learning of energy and its related concepts and recommendations for further research are discussed. KEY WORDS: biology, context, diagnostic test, energy, understanding

INTRODUCTION Amongst science educators, there is a general agreement on the importance of the concept of energy as a focus of interest in the science curriculum. This is because energy is a central idea which provides an important key to our understanding of the way things happen in the biological, physical and technological world (Liu, Ebenezer & Fraser, 2002). Furthermore, energy is one of the science concepts that cuts across all science disciplines and is experienced in our everyday life situations (Saglam-Arslan & Kurnaz, 2009). As a result, an understanding of the energy concept is crucial to the promotion of scientific literacy amongst students and citizens at large. The centrality of the concept energy to International Journal of Science and Mathematics Education (2012) 10: 241Y266 National Science Council, Taiwan (2011)

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science disciplines and to our society has led to a series of studies on students’ understanding of energy (Boyes & Stannistreet, 1991). In general, science education research has shown that there are serious difficulties in understanding energy and its related concepts amongst students of all ages (Becu-Robinault & Tiberghien, 1998; Liu et al., 2002; Saglam-Arslan, 2010). These difficulties arise from the fact that energy as a science concept and energy in everyday life usage have two different meanings. The dissimilarity between the everyday notions and the scientific explanations of energy cause the latter aspects to make no sense to many learners—a factor which could promote the existence of erroneous ideas about this concept. Many students do not realise that, regardless of the context in which the term energy is used, they are dealing with the same concept (Linjse, 1990; Trumper, 1997). Several science education studies have shown that many students and science teachers hold erroneous ideas about energy and energy-related concepts (e.g. Barak, Gorodetsky & Chipman, 1997; Bliss & Ogborn, 1985; Boyes & Stannistreet, 1991; Duit, 1984; Fetherston, 1999; Gayford, 1986; Goldring & Osborne, 1994; Kesidou & Duit, 1993; Kruger, Palacio & Summers, 1992; Linjse, 1990; Mann, 2003; Nicholls & Ogborn, 1993; Saglam-Arslan, 2010; Sanders, 1993; Solomon, 1992; Trumper, 1997). Table 1 shows some previous studies (in chronological order) and the corresponding student errors about energy and energy-related concepts. In particular, these studies have found the following errors: Students erroneously think that energy is synonymous with other words such as force, power and electricity; students erroneously believe living matter has a unique kind of energy different from non-living matter; students fail to apply the energy conservation principle (energy cannot be created or destroyed) to biological systems; students erroneously think that energy for metabolism and life processes is made available during digestion in animals and during photosynthesis in plants; students erroneously think there is no energy involved/present in inanimate and/or non-moving objects. In view of the previous research findings on energy concept outlined in Table 1, it became imperative for us to revisit these studies in order to see the instruments used and the contexts in which students’ understanding of energy were carried out. First, we found that a variety of instruments were used, but the most common ones included open-ended survey questionnaires (e.g. Duit, 1984; Linjse, 1990; Liu et al., 2002; Saglam-Arslan, 2010; Solomon, 1992), two-tier diagnostic tests (e.g. Haslam & Treagust, 1987; Mann, 2003; Sanders & Cramer, 1992; Trumper, 1997) and drawings (e.g. Bliss & Ogborn, 1985; Kruger et al., 1992; Watts, 1983;

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Kose, 2008). Each of these instruments has strengths and weaknesses. For example, whilst open-ended questions can allow students freely write whatever is on their mind (Liu et al., 2002), the wording, phrases and/or language used could be ambiguous or misunderstood by students (Duit, 1984). Two-tier diagnostic tests typically involve a content question with multiple-choice answers derived from students’ alternative conceptions gathered in the literature and further require respondents to provide explanations for their answer choices (Haslam & Treagust, 1987). Twotiered questions have two main benefits: First, the random correct guesses to the question are accounted for. Second, they allow for the probing of two aspects of the same phenomenon—which include basic knowledge (scientific facts) and conceptual understanding (ability to provide explanations). However, respondents may easily guess the correct answer choice but fail to explain—a situation which may pose a difficult for the researcher(s) to determine the level of the respondents’ understanding of the concept being tested. The advantages of using drawings in diagnosing misconceptions is that they can allow students to express their thoughts and feelings, mainly because they reflect an image of what is on their mind (Thomas & Silk, 1990). Rennie & Jarvis (1995) further argue that drawings allow students with difficult expressing their thoughts verbally to be able to communicate. However, the major disadvantage with drawings is that some ideas may not be effectively represented in diagrammatic form. In our study, the diagnostic test developed incorporated open-ended items, statements gathered from students’ alternative conceptions derived from the literature and two-tier items which probed for both knowledge and conceptual understanding of energy and diagrams (see “METHODOLOGY” section for the actual test items). Second, when we scanned through the instruments, we found that most of the test items were presented in physics- and engineering-oriented contexts (e.g. Duit, 1984; Fetherston, 1999; Kesidou & Duit, 1993; Kruger et al., 1992; Liu et al., 2002; Watts, 1983), and very few studies used test items which were in a biological context (e.g. Baker, 1985; Barak et al., 1997; Mann, 2003). Third, the few studies that had a biological leaning had test items specific to biology topics such as photosynthesis (Eisen & Stavy, 1988; Haslam & Treagust, 1987; Kose 2008), respiration (Sanders, 1993; Sanders & Cramer, 1992), plants (Baker, 1985) and animals (Boyes & Stannistreet, 1991). Fourth, very few studies used test items which reflected the everyday life situations despite the findings that students have ideas about energy from this perspective. In our opinion, the students’ conceptual difficulties are interrelated and connected to other aspects such as everyday life and science discipline

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TABLE 1 Summary of students’ erroneous ideas about energy and energy-related concepts, in percentages

Errors relating to definitions of energy Energy is force 20 72 * 35 Energy is work 60 Energy is electricity 13 * Energy is power 18 * Energy is a physical entity 63 Errors relating to the vitalistic views about energy Living matter is governed by a unique form of energy which is different from the one in non-living things. 69 * Errors relating to the idea that energy is not conserved in biological systems and processes Students’ responses to energy-related concepts do not reflect (or if they do), contradict the idea of energy conservation & transfer in biological systems. * * 100 Energy is used up/consumed during processes in living things * 29 Errors relating to the sources of energy for metabolic processes in living organisms Photosynthesis is the process that directly provides plants with the energy they need for life processes (e.g. growth) Digestion is the process that provides animals with energy for life processes (e.g. growth) The sun is the direct source of energy for metabolic processes in living organisms Plants obtain energy from soil Plants obtain energy from water Animals get their energy from resting (e.g. when asleep) Errors relating to situations in which energy is involved Energy is involved or found in living organisms only Energy is not involved in non-moving objects (e.g. statue) Energy is not involved when a person is not active (e.g. when asleep) Errors relating to associating energy to an obvious activity Energy is an obvious activity / movement Energy is (only) present if there is movement

61

Saglam-Arslan (2010) n=243 (Turkish high school & university students)

Sanders (1993) n=136 (South African biology teachers) Barak et al. (1997) n=104 (76 Israeli high school students & 28 biology teachers) Trumper(1997) n=189 (Israeli pre-service biology teachers) Fetherston (1999) n=94 (Australian secondary school students) Mann (2003) n=610 (Australian secondary school students)

Kesidou et al (1993) n=34 (German secondary school students

Linjse (1990) n=97 (Dutch secondary school students) Boyes et al (1991) n=109 (English undergraduate students) Kruger et al. (1992) n=159 (English primary school teachers) Solomon (1992) n=not stated (English secondary school students)

Bliss et al (1985) n=17 (English secondary school students)

Some erroneous ideas about energy and its related concepts, as identified by different researchers

Duit (1984) n=761 Primary & Secondary School (176 Filipinos & 585 Germans)

Researchers who identified the errors

* *

9 * 79

*

*

*

63

*

15

42 67

53 27 31 28 6 53 100

* 20

9

* *

11 *

*

* 7

*

* represents that corresponding error was observed, but no exact percentages of students holding the error was given.

contexts, which have not been sufficiently taken into account in previous diagnostic research on energy concept. In this paper, we defined context as a setting in which students’ understanding are being sought from. Given that energy cuts across science disciplines and is an abstract concept, we believe that context plays a role in determining students’


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understanding. We also believe that for any concept to make sense and be meaningful in a particular science discipline, the concept must be seen as being part of the students’ everyday and social environment and be of relevance. A satisfactory approach to diagnosing students’ understanding of energy or any other science concept is one which takes into account the context in which the knowledge is constructed in order to yield authentic and meaningful data. To date, most of the previous studies revealed have not asked students to explain energy in a biological context. Therefore, the main purpose of this study was to conduct a diagnosis of first-year university biology students’ understanding of energy and biological-context energy concepts using an instrument with items reflecting the science discipline context (in this case biological science) and everyday life situations by using closed statements and diagrams depicting biological phenomena. A secondary aim of the study was to develop a pencil-and-paper test which could easily be administered by science educators to diagnose students’ understanding about energy and biological-context energy concepts. The two research questions that guided this study were: (1) What ideas are held by first-year university students about energy and energy-related concepts in biological context? (2) Can a reliable pencil-and-paper test be developed to diagnose students’ understanding of energy and energy-related concepts involving biological phenomena?

METHODOLOGY Sample Description The sample consisted of 90 first-year biology students at a South African university. There were 40 males and 50 females. All these students were in a pre-medical program in which they were preparing to go to medical school. Development of Diagnostic Test A survey approach was used for the research, using a pencil-and-paper diagnostic test specifically developed to collect the data. The design of the diagnostic test was based on a process described by Haslam and Treagust (1987). The development of the test involved two main phases: the preparatory and the test formulation phases. The preparatory phase involved three steps. Step 1 involved the drawing up a list of scientifically acceptable propositional knowledge statements about energy and bio-

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logical-context energy for this study. This list was drawn up after interviewing three biology lecturers and then consulting the two prescribed tertiary level textbooks for first-year biology courses at the university where the study was conducted (i.e. Raven & Johnson, 1999; Solomon, Berg, Martin & Villee, 1993). The purpose of this step was to draw up the energy conceptual structure (see Figure 1) that defined this study and which was used as a guide when constructing the test items and when marking the answers. Step 2 involved compiling a list of common erroneous ideas about energy and energy-related concepts, reported in the research literature (see Table 1). The purpose of this step was to compile a list of common erroneous ideas about energy held by students in previous research studies, so these could be included in the diagnostic test to be developed. Step 3 involved defining the content boundaries of the test so that topics which students were expected to know when they enter first year would be included in the test, in order for the test to be used to diagnose prior knowledge as well. The information for this step was acquired through interviews with lecturers who provided data on the prerequisite knowledge required in first year biology. In the test formulation phase, the diagnostic test had to fulfil two basic criteria: checks basic knowledge about energy and tests understanding of energy-related concepts. Testing for understanding is not an easy matter. Various authors have listed criteria that could be used in judging understanding. For example, Sanders & Mokuku (1994) stated that individuals who understand a concept should know and be able to recognize the name and definition of a concept, be able to define and explain the concept in their own words, be able to recognize instances not previously encountered of the concept, be able to distinguish between and classify instances and non-instances of the concept not previously encountered and be able to apply the concept to new situations. Other researchers have argued that students’ complete conceptual understanding of a science concept and the ability to apply these ideas can be determined by using multi-modal representations which combine text, verbal discourse, mathematical expression, graphical–visual representation such as diagrams and motor operations (Hand, Gunel & Ulu, 2009; Prain, Tytler & Peterson, 2009). Through these multiple representations, students are able to clarify their thinking and offer scientific explanations that can reveal their mental constructions. A number of these criteria were considered when designing the test. The test items were constructed in such a way that students were required to explain the concept energy in their own


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ENERGY CONCEPTUAL STRUCTURE DEFINED IN THIS STUDY [Compiled from the Prescribed Textbooks: Raven & Johnson (1999) & Solomonet al., (1993)] 1.

Definition of energy: Energy is `the capacity to do work. In a biological context, energy is concerned with the ability of living systems to do work such as breathing, digestion, blood circulation, muscle contractions, movement of substances across cell membranes against concentration gradients and the maintenance of all metabolic processes. 2. Conservation of energy: According to the first law of thermodynamics (the law of conservation of energy), energy cannot be created or destroyed, but it can be converted from one form to another work. All energy forms are inter-convertible from one form to another without any ‘loss’. Any apparent loss of energy can be explained as the conversion of energy into some other form. For example, during each energy conversion in living systems, some of the energy is used to drive the metabolic processes and some of it dissipates to the atmosphere in the form of heat. In biological systems, most reactions of organisms involve a complex series of energy transformations. During photosynthesis, plant cells transform light energy to chemical energy stored in chemical bonds of food materials. Some of this chemical energy may eventually be converted to mechanical energy in animals for muscle contraction, if the plant is eaten by an animal. 3. Purposes of energy in living organisms: In plants, energy is needed: To manufacture food, especially carbohydrates, during photosynthesis. To transport water, mineral salts and solutes across cell membranes. During reproduction and germination of seeds and for all metabolic processes. In animals, energy is required: For processes which include: the pumping of blood in the circulatory system, the digestion process when food is pushed along the alimentary canal, gaseous exchange in the lungs, the excretion of metabolic waste products from animal bodies, reproduction processes, contraction of muscles in order to allow movement, transmission of nerve impulses. To transport solutes across cell membranes and for all metabolic processes. 4. Metabolic process that makes energy available in living organisms: Autotrophs/Producers: These are organisms that synthesize all needed organic molecules from simple inorganic substances, and include plants, algae and certain bacteria. They produce energy-containing organic food molecules using the inorganic molecules (i.e. carbon dioxide and water in the presence of sunlight or radiant energy and photosynthetic pigments during the process of photosynthesis. Heterotrophs: These are organisms which cannot synthesize their own food from inorganic materials, and include all animals and humans. They take in energy-containing organic molecules (food) by eating / feeding on autotrophs such as plants or by eating other heterotrophs which have eaten the plants. The three major food-groups for heterotrophs are carbohydrates, lipids and proteins. These large food molecules are then hydrolyzed to smaller and soluble molecules by enzymes during chemical digestion. For instance, Amylase enzymes are involved in the hydrolysis of carbohydrates to produce glucose. In order for heterotrophs to access the stored energy so that they can perform biological work, glucose has to be oxidized to release energy in a readily available form during the process of respiration. 5. Situations in which energy is present: Energy is present/involved in all matter (living, non-living, moving, and non-moving matter) 6. Types of energy: Energy exists in various forms including radiant, potential, chemical, kinetic, electrical, heat. Radiant or light energy is the light that reaches the earth from the sun. In biological sciences, radiant energy is of prime importance because it is the energy which is captured by photosynthetic organisms for the synthesis of organic compounds during photosynthesis. Potential energy is “the energy possessed by a body as a result of its position or configuration Raven and Johnson (1999), define potential energy as “stored energy”. For instance, food materials in both plants and animals contain potential energy. The potential energy in molecules of primary fuels such as coal, wood, and food materials is also referred to as chemical energy. Kinetic energy is “the energy possessed by a body as a result of its motion”or it is “the energy of motion” . For instance, the energy of muscle movements and transport of materials in biological organisms is kinetic energy. Even in stationary objects such as a statue, kinetic energy is present in that the molecules in the statue are in constant motion. Electrical energy is the energy that is present in electric circuits, charged capacitors and electromagnets. In biology, electrical energy is used during the transmission of nerve impulses in animals, such as man. Heat energy is the “energy of molecular motion”. All other forms of energy can be converted into heat. In biology, energy is dissipated to the environment in theform of heat during metabolic processes.

Figure 1. Energy and biological-context energy conceptual structure

words and to apply their understanding of energy in the closed statements and in the diagrammatic situations given. Quality-control steps taken whilst the instrument was developed included checks on content validity and rigorous face validation by five university biology and physics experts. The instrument was piloted with 30 first-year biology students who were not involved in the main study. Piloting is an important quality-control procedure as it enables to check on the suitability of individual test items, to gain feedback on how well

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participants understood the questions, response procedures and instructions so that questions can be improved (Bell, 1987). The pilot group was requested to indicate whether they had problems understanding what they were required to do in each question. They were also further requested to write down the words or phrases which were not clear to them. The results of the pilot showed that 90%, 83% and 57% of the students had no problems with the diagnostic test questions 1, 2 and 3, respectively (see test questions in next section). Majority of the students who indicated having problems, especially for question 3, suggested their inability to give answers due to lack of knowledge about energy types. Therefore, no test items were dropped. Diagnostic Test Instrument The instrument consisted of three main questions. Question 1 was an open-ended question aimed at eliciting students’ conceptual understanding of the term energy in the biological context. The actual question 1 read: The term energy is often used in biology. Explain what you think energy is in a biological context. Question 2 consisted of 11 closed-ended statements phrased in biological context and reflecting everyday life situations (see Table 5 for the actual statements). The actual question 2 read: Below are some statements about energy. (a) For each statement, indicate by placing a tick (✓) in the appropriate box if the statement is scientifically correct or incorrect; (b) If the statement is incorrect, underline the word or phrase in the statement which makes it incorrect; and (c) Then write in a word or phrase which would make the statement correct. Question 3 involved diagrams of four situations which are a man playing soccer, a growing potted plant, a statue and a lion eating a dead zebra (see Table 6 for the actual diagrams). This question was aimed at testing whether the students knew that energy is present or not and if they could list the types of energy involved in each of the four situations. The actual question 3 read: Each of the situations shown below may involve energy in some way at either the microscopic or molecular levels. Complete the table by indicating whether energy is present or not; and stating the type(s) of energy involved. Data Analysis The data were analysed using open-coding and reported as frequency counts. After a line-by-line analysis of each script, categories and subcategories to which responses would fit well were developed. The categories which had been developed were given to two experts, a biology


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educator and a physics educator, for validation. These experts were asked to check for the following: the scientific correctness of the answers given by students, the appropriateness of the categories developed for the student answers and whether the students’ responses were correctly categorised. This was done by giving each expert ten scripts to go through and code independently. Any differences in the coding were discussed collectively, and a common agreement reached. When individuals rate a product, there is always a possibility that some portion of the agreement between them is due to chance. Cohen (1960) recommends using the kappa statistic to assess interrater agreements involving nominal scale. Cohen’s kappa (k) is a coefficient of interrater agreement that takes into consideration agreement by chance. The interrater agreements between the biology and physics educator on the scientific correctness of the answers provided by students are shown in Table 2 below. The percentage of agreement on the analysis of students’ responses to diagnostic test ranged from 80.0% to 92.5% with a corresponding kappa coefficients range of 0.78 to 0.90. The percentage agreement of more than 75% and kappa values above 0.5 are considered to indicate good level of interrater agreement (Chiapetta, Fillman & Sethna, 1991). Therefore, the values in this study can be considered good enough to justify reliability. After the categorization process on the scientific correctness of the responses, frequency counts were conducted to get the actual number of students giving each answer and to calculate the percentages. The results are presented in the next section. RESULTS AND DISCUSSION The results have been presented along with the discussion. This is because certain aspects of energy such as what constitutes the complete TABLE 2 Interrater agreement values Test item

Percent agreement

Kappa value

Definition/explanation of energy Types of energy involved Many playing soccer Growing plant Statue Lion eating a dead zebra

85.4

0.80

85.0 80.0 92.5 84.1

0.85 0.78 0.90 0.84

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explanation of energy need to be discussed alongside the scientifically acceptable perceptions of what energy is/involves, before presenting the results so that the reader(s) can have a clearer perspective as to why the authors of the current study categorised some statements as scientifically correct or incorrect. Students’ Understanding of Energy The students’ conceptual understanding of energy was elicited in question 1 which read: “The term energy is often used in biology. Explain what energy is in a biological context”. In analysing the students’ answers, these three aspects were considered: the extent to which the concept energy was correctly explained, the extent to which the concept energy was explained in a biological context and the ideas which students expressed about the energy concept. Explanations of the Energy Concept. Even if students were required to explain what energy is, it became apparent that many opted only to define energy rather than explain the term. Although in this study the definition “energy is the ability to do work” was accepted as correct, the reader is reminded that many authors regard it as being incomplete (e.g. Kemp, 1984; Warren, 1986) and argue that extra information is needed before the definition can be considered to be complete. For example, Trumper (1990) and Warren (1986) argue that a traditional definition of energy as the ‘ability to do work’ may only be meaningful if additional information concerning energy transformation and its conservation, and types of energy are mentioned (essentially the two kinds of energy are potential and kinetic, but traditionally, the following types are also named chemical, radiant, light, electrical and mechanical energy). Therefore in this study, we judged the completeness of each students’ explanation of what energy is based on whether the paragraph had the traditional definition of energy (i.e. energy is the ability/capacity to do work), accompanied by additional information concerning types of energy, energy transformation and its conservation. Table 3 summarises the categories of the explanations given by the students when they were asked to explain the meaning of energy. About 44% of the students gave a correct traditional definition of energy, but out of these, a large proportion of them (24%) did not write any additional statements. In this case, Duit (1984) argues that it is difficult to distinguish whether a definition, on its own, is based on understanding or has merely been rote-learned. Although quite a


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reasonable number of students in our study gave a traditional and correct definition, the presence of additional incorrect statements may suggest that some students (18%) could have just rote-learned the definition. In summary, only 2% of the students in the whole sample did what the question asked them to do, i.e. explain energy and give a completely correct answer. Extent to Which Energy Was Explained in a Biological Context. Despite having asked the question in a biological context, some students gave answers which were general, and not explained in a biological context. An analysis of the answers shows that 48% of the students linked their responses to living organisms (biological contexts), and 52% gave

TABLE 3 Categories of students’ explanations of energy Students’ explanations of what energy is

% of students

Definition correct with …

44 2

Additional statements explaining energy, all correct Additional statements explaining energy, some correct and some not Additional statements explaining energy, but all incorrect No additional statements explaining energy provided Definition incorrect with … Additional statements explaining energy, all correct Additional statements explaining energy, some correct and some not Additional statements explaining energy, but all incorrect No additional statements explaining energy provided No definition, but with … Additional statements explaining energy, all correct Additional statements explaining energy, some correct and some not Additional statements explaining energy, but all incorrect

4 14 24 37 7 7 7 17 18 4 8 6

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responses which were worded in a physics oriented context. This finding suggests that many students think of energy in physics- or engineeringoriented contexts more than in biological contexts. An example of an explanation of what energy is in a biological context was provided by student number 4 who wrote: “energy is the capacity to do work that drives processes such as the pumping of blood in the circulatory system and the contraction of muscles in order to allow movement”. On the other hand, student number 12 provided an explanation of energy in a nonbiological context by stating: “energy is the capacity to do work, and this is applied only to machines and mechanics”.

Ideas Expressed by Students About the Energy Concept. The ideas expressed by students included many categories of unsuitable or incorrect statements, often as a result of the words used in the explanations. For example, some students wrote sentences such as “energy is used up during vigorous activity in living organisms”. Whilst such a statement could be true if one allows for a student’s terminology, it is scientifically incorrect simply because of the phrase ‘used up’ which violates the energy conservation principle from the scientific language point of view. The categories of students’ ideas about energy are provided in Table 4, and the statements have been categorised as scientifically acceptable or unacceptable, after discussion with the two university physics and biology ‘experts’ who judged the correctness of the answers. The results show that slightly less than half the students (44%) gave the traditional and correct definition that ‘energy is an ability (or capacity) to do work’. Amongst the incorrect definitions, those of energy being work, power and force were popular. These results were also found in previous studies (e.g. Duit, 1984; Kruger et al., 1992; Kesidou & Duit, 1993; Solomon, 1992; Trumper, 1997; Trumper & Gorsky, 1993). From the biological point of view, 33% of the students provided acceptable statements about what energy does in living organisms. About 21% of the students provided statements about energy conservation. Of these half correctly stated that energy cannot be created nor destroyed. The rest used the terms used up, created, made or lost in their explanations, and the researcher judged these to imply that these students could not apply the principle of energy conservation. Similar problems were documented in previous studies (e.g. Duit, 1984; Kesidou & Duit, 1993). It appeared that although some students in this study could recall and state the principle of energy conservation (i.e. energy cannot be created or destroyed), some reverted back to their everyday understanding of energy

78

Statements to do with definitions of energy Scientifically acceptable statements Energy is the ability/capacity to do work Energy is the catalyst/fuel needed by a body to facilitate its metabolic rate Scientifically unacceptable statements Energy is the work done Energy is the power required to perform any task Energy is force Energy is a physical quantity which enables work to be done Statements to do with what energy does in living organisms Scientifically acceptable statements Energy is required by all living organisms for life processes such as movement/growth Energy is needed for all metabolic and all life processes Statements to do with energy conservation Scientifically acceptable statement Energy cannot be created nor destroyed Scientifically unacceptable statements Energy is used up during processes (e.g. exercises, respiration) in living organisms Energy is created/made (during photosynthesis) in plants and during cellular respiration Energy is lost during its transfer/decreases during an activity Statements to do with energy as a ‘thing’ or quantity Scientifically acceptable statement Energy is something that is needed by all living organisms for metabolism Energy is a by-product released during respiration

3 7

4 4 2 26

11

17 16 21

11 10 3 3 33

44 7

% of students

Categories of students’ statements about energy

Categories of students’ statements when explaining energy

TABLE 4 DIAGNOSING STUDENTS’ UNDERSTANDING OF ENERGY IN BIOLOGY

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Scientifically unacceptable statements Energy is a substance/chemical catalysing reactions in living and non-living things Energy is something produced in a reaction of forces/enables particles to interact Energy is the rate/amount needed to perform a certain job or produce a force Statements to do with energy transformations/transfer Scientifically acceptable statement Energy can be transformed or converted from one form to another Energy can be transferred from one organism to another Statements to do with the types of energy Scientifically acceptable statements Many types of energy occur (e.g. kinetic, potential, chemical etc.) There are two types of energy: kinetic and potential Scientifically unacceptable statements ATP, ADP NADH2 and FADH2 are energy types needed by biological cells Statements to do with where energy comes from Scientifically acceptable statement Humans get energy from the food they eat Energy comes originally from the sun Energy for life processes is made available during respiration in living organisms Scientifically unacceptable statements Photosynthesis provides the energy in plants Scientifically unacceptable miscellaneous statements e.g. energy is life, creates life, everything, can be absorbed, is a source

(continued)

TABLE 4

3 17

3 2 3

3 11

8 1

7 6 12

6 3 7 13

254 VIVIEN MWEENE CHABALENGULA ET AL.


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being used up, created or lost during activity, when they had to apply their knowledge in questions 2 and 3. Several authors have indicated that students have difficulties in applying the energy conservation principle to biological phenomena (e.g. Liu et al., 2002; Solomon, 1985; Warren, 1986). Warren further explained that the conservation of energy is problematic because it implies saving fuel when used in everyday life and social understanding. The finding from this study is valuable to science educators particularly biology educators because they have a job of explaining how energy and its related concepts cut across science, biology included. Twenty-six percent of the students explained energy as if it is a concrete object (e.g. a physical quantity). Similar findings are reported by several researchers (Duit, 1984; Eisen & Stavy, 1988; Trumper & Gorsky, 1993). Duit (1984) indicated that “thinking of energy in terms of a thing, is not in line with the usual conception of energy in science”. About 11% of the students included statements referring to where energy comes from, and 3% of these stated that humans get energy from the food they eat, which is technically correct. However, Sanders & Cramer (1992) found that several students in their study believed that digestion is the process which provides energy for metabolism, so it is possible that the three students in this study may hold an erroneous idea. Understanding of Energy in Statements Involving Biological Phenomena The students’ understanding of energy in the provided statements reflecting biological phenomena and everyday life situations was elicited in question 2 which read: Below are some 11 statements about energy (see Table 5 for the actual statements). Task 1: For each statement, indicate by placing a tick (✓) in the appropriate box if the statement is correct. Task 2: If the statement is incorrect: (a) Underline the word or phrase in the statement which makes it incorrect, and (b) Write in a word/ phrase which would make the statement correct. The analysis of the responses to the statements showed that misunderstanding of some energy-related concepts exists amongst many students. Two important points to note as one reads the results. First, it is important to state here that many students (38% of them) did not attempt to underline the word or phrase making the statement(s) incorrect, or to write in the word or phrase which would correct the statement(s) which they had indicated were incorrect. The possible validity problem associated with this is that it is not clear whether the students who did not give responses did not follow the instructions, or whether this indicated a lack of understanding of the concepts. Second, the statements

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TABLE 5

If you go jogging, energy is used up*

After exercise, you can build up your energy levels by resting*

When you are asleep your body does not require any energy because it is not active*

The energy needed by plants and animals for various metabolic processes is made available during respiration** Living organisms have a kind of energy which is different from the energy we learn about in physical science* The energy which plants need to maintain life processes (such as reproduction) is released during photosynthesis* Energy cannot be created or destroyed**

Statement Incorrect (%)

Statements reflecting biological phenomena

Statement Correct (%)

Students’ responses to the provided statements about energy and its related concepts

92

7

43

7

56

92

87

11

53

44

46

51

98

1

Plants get the energy they require for their life processes (for example, growth) directly from the sun* During exercise, energy is built up in the body*

78

20

When living things are active, they lose energy*

59

The energy needed by animals for movement is provided by the process of digestion*

16

55

82

40

44

Task 1 Underlined word or phrase which makes statement incorrect

Incorrect phrase -used up Incorrect phrase -build up Incorrect word -resting Incorrect phrase -does not require energy Incorrect phrase -not active Problematic word*** -respiration

%

4

10 24

38 14 7

Task 2 Written-in Word or phrase which make statement correct

Acceptable - converted to different forms Unacceptable -lost Acceptable -do not build up Acceptable -eating(food consumption) Unacceptable -stop using energy Acceptable -require energy - body processes still occur Acceptable -is active Unacceptable -photosynthesis

%

3 1 4 15 4 16 9 8 7

Incorrect word -different

17

Acceptable -the same

13

Incorrect word - photosynthesis

19

Acceptable -respiration

13

Problematic phrase*** -created / destroyed Incorrect phrase - directly from the sun

11

Incorrect phrase -built up

47

Incorrect word -lose Incorrect word -digestion

1

28

21

Unacceptable -transferred Acceptable - has to be converted initially Acceptable - converted to different forms Unacceptable - used up - lost Acceptable -convert it to different forms Unacceptable -use up Acceptable -respiration Unacceptable -breathing

1 6

7 26 8 7 11 13 4

* Statement is scientifically incorrect; ** Statement is scientifically correct; and *** Word or phrase which students underlined as being incorrect is in fact scientifically correct.

with subject/topic specific concepts (such as respiration, photosynthesis and digestion) may have influenced students’ responses to the questions depending on how well they understand that particular topic. In both cases, it would have been of value to interview some of these students. However, interviews were not conducted because one of the purposes for this study was to develop a pencil-and-paper diagnostic test that could be used to diagnose students understanding of energy in biological contexts and which teachers can easily administer. Understanding of Energy Conservation Principle. Nearly all students (98%) correctly indicated that the statement on the principle of energy


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conservation, energy cannot be created or destroyed, is scientifically correct. However, the students’ actual understanding of this principle was cross-checked to determine if they could apply their knowledge in other statements which tested the same concept in the diagnostic test question 2. These statements were: If you go jogging, energy is used up; After exercise, you can build up your energy levels by resting; When living things are active, they lose energy. The contradictory answers given to these statements could suggest that the students are unable to apply the idea of energy conservation. The inability of students in this study to consistently apply the energy conservation principle may suggest that students could have rote-learned this law or could have seen it in textbooks. Another source for this problem could be the language differences between science and everyday usage. Using phrases such as used up, build up or lost are not scientifically correct when talking about energy conservation. Understanding of Energy Conversion and Transfer. The idea of energy conversions and transfer is loosely understood by nearly all students in this study. That is, 92% of them erroneously indicated that the statement if you go jogging, energy is used up is correct. In this study, only 4% of the students in the whole group correctly underlined used up as an incorrect phrase and wrote in the scientifically acceptable phrase, converted to different forms. Similarly, Mann (2003) also found that many students had poor understanding of energy conversion and transfer. Ninety-two percent of the students correctly identified the statement when you are asleep, your body does not require any energy because it is not active as scientifically incorrect. Most students appeared to understand that the human body is active even at rest, and therefore, energy is always required. Understanding of Energy Sources for Metabolic Processes. Many students (87%) correctly indicated that the statement the energy needed by plants and animals for various metabolic processes is made available during respiration is correct. However, several students stated that the statement was incorrect and erroneously underlined respiration as the word making the statement incorrect. This group of students went on to erroneously write-in photosynthesis as a word which would correct the statement. This erroneous idea was actually probed further in the diagnostic test, using the statement the energy which plants need to maintain life processes (such as reproduction), is released during photosynthesis. This time a much larger proportion of the students revealed a possible erroneous idea,

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with 46% of the students in the sample erroneously indicating that the statement was correct. A possible explanation for this inconsistency could be due to students’ lack of conceptual understanding of the difference between photosynthesis and respiration. Other researchers (e.g. Mann, 2003) also document that the process of respiration is poorly understood by students. The process of digestion was also erroneously identified as the source of energy for processes such as movement in animals. More than half of the students (55%) erroneously indicated that the statement the energy needed by animals for movement is provided by the process of digestion was correct. Similar findings in which students were found to have this erroneous idea have been documented in previous studies (e.g. Sanders & Cramer, 1992; Sanders, 1993). This implies that these students do not understand that from digestion, food has to be oxidized during respiration so that energy can be made available for life processes. Understanding of Whether Biological Systems Have a Unique Kind of Energy. One statement tested students on whether living matter (biological organisms) is governed or has a unique kind of energy different from non-living matter. This kind of thinking is referred to as vitalism (Barak et al., 1997), and it was tested using the statement living organisms have a kind of energy which is different from the energy we learn about in physical science. More than half of the students (53%) erroneously indicated that the statement was correct. Other studies also documented this finding (e.g. Barak et al., 1997; Kruger et al., 1992). Barak et al. explained that this erroneous thinking has been exacerbated by the idea that living matter is made of special constituent materials which differed from non-living matter and requires a ‘vital force’ (i.e. a unique form of energy) different from other forms of matter. The current scientifically acceptable view of energy is that whilst living systems are unique, biological phenomena can be understood within the framework of concepts applied to physics and chemistry. Understanding of Energy in Diagrams Involving Biological Phenomena Students’ understanding of energy in diagrams reflecting biological phenomena and everyday life situations was elicited in question 3 which read: Each of the diagrams shown may involve energy in some way at either the microscopic or molecular levels (see the actual diagrams in Table 6 below). Complete the table by: (a) Indicating whether energy is


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present or not, by placing a tick (✓) in the appropriate column. (b) Stating the type(s) of energy involved in each diagram. Table 6 shows the results. Generally speaking, many students’ answers on whether energy is present or not in the diagrams were in line with the scientific viewpoint, except for the case of the statue, where 64% of them erroneously indicated that there is no energy present. This is a fairly common misconception even in previous studies (e.g. Bliss & Ogborn, 1985). With respect to naming the types of energy involved in the four situations, four issues became evident. First, many students did not attempt to answer certain parts of the question (specifically nine students and 18 students did not attempt to name energy types involved in the growing plant and in the lion eating a dead zebra, respectively). This could suggest lack of understanding, or students being unsure of what to write. Second, many students did not think far into the idea that molecules in all matter are in constant motion—a scientific explanation which justifies why kinetic energy is involved even in stationary objects such as a statue, at molecular level. In this study, only 2% of the students correctly indicated that kinetic energy is involved in the statue. Third, many students used processes to make up a name for a type of energy, such as respiration energy, photosynthetic energy and nutritional energy. Fourth, many students did not seem to realise that certain types of energy were present in the pictures depicted, particularly in the pot and soil in which the plant was growing. A possible explanation for this is that both the pot and soil are non-living objects, and students may hold an erroneous idea that energy is only involved in living things. Several researchers have also found that many students erroneously believe energy is only involved in living organisms (e.g. Kruger et al., 1992; Mann, 2003; Trumper, 1997).

IMPLICATIONS FOR TEACHING AND SCIENCE CURRICULUM The answers provided by the students suggest that many students have an incomplete understanding of energy and energy-related concepts related to biological contexts. The question which then arises is: What should be done about the problems students have in understanding the energy concept? There are several potential areas in which teachers can get involved, if problems faced by students are to be minimised. First, based on the results of this study, it is important to alert teachers to the fact that even those students who are able to provide a traditional

260


TABLE 6 Responses on whether energy is present or not and types of energy involved Diagram situations Man playing soccer

Growing potted plant

Energy present (%) 99

98

Energy not present (%) 0

0

Statue 31

Lion eating a dead zebra

96

64

0

Types of energy involved (%) Man Scientifically acceptable Kinetic energy Chemical energy Potential energy Mechanical energy Heatenergy Scientifically unacceptable respiration energy Ball Scientifically acceptable Potential energy Kinetic energy The plant Scientifically acceptable Chemical energy Radiant energy Kinetic energy Potential energy Light energy Scientifically unacceptable Photosynthetic energy Respiration energy Scientifically acceptable Potential energy Kinetic energy Scientifically unacceptable No energy is involved

Lion Scientifically acceptable Kinetic energy Chemical energy Mechanical energy Potential energy Heat energy Scientifically unacceptable Respiration energy Dead zebra Scientifically acceptable Potential energy Chemical energy Scientifically unacceptable nutritional energy

86 26 14 12 10 3

9 4

45 27 17 14 10 4 7 30 2 60

43 27 10 8 3 5

13 11 2

definition of energy might hold erroneous ideas about energy. This implies that teachers should not assume that if students are able to provide some answers, they understand. Second, it is important that teachers identify students’ prior ideas before starting to teach energy and its related concepts (e.g. Driver, Squires, Rushworth & WoodRobinson, 1994; Fetherston, 1999; Solomon, 1982). This is because energy has everyday meanings which may conflict with those of


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science—a situation which can make students’ responses scientifically incorrect. One possible way to do this is by using diagnostic strategies that can identify students’ incorrect ideas before instruction. Several methods which can be used to do this, including interviews, class discussions and a range of pencil-and-paper tasks such as tests, annotated drawings and so on. Third, it is recommended that teachers explain why certain words such as used up, created and lost are unacceptable when talking about energy, since many students had problems with the energy conservation principle. It is hoped that if teachers introduce and discuss the erroneous words or phrases, it may serve as a basis for alerting students to the problems involved in using them. Fourth, the results of this study showed that some students did not think energy is involved in stationary objects, e.g. the statue and in inanimate objects such as the ball, the pot and the soil. This problem can be addressed by teachers if more consideration is given to teaching about energy at both the microscopic and macroscopic levels. Bunge (2000) argues that a failure to address either level may result in difficulties in developing a complete understanding of the energy concept. Fifth, there seemed to be a lack of understanding amongst many students that whilst energy is involved in processes of photosynthesis and digestion, it is only made available for use in other forms of metabolism during respiration. Therefore, the concept of energy transformation could be one of the ideas which biology teachers could emphasize more when teaching. As stated by Gilbert, Osborne & Fensham (1982), one of the unintended learning outcomes which results when students’ prior ideas are not appropriately dealt with is that students stick to their own prior ideas in spite of teaching. Therefore, teachers need to introduce the energy-related topics in a way which makes students aware that their existing ideas about energy are not plausible. One way is to provide evidence (verbal or practical) that certain ideas are not logical or not possible. Science teachers are also reminded to realise that it is necessary to provide students with a variety of situations, experiences and activities when teaching the energy concept in order to overcome the usual conceptual reductionism. Since energy is an abstract concept, yet has everyday life connotations, students’ understanding would be enhanced if the learning activities are based in all contexts in which students construct their knowledge, particularly across science disciplines and everyday life contexts. Other researchers (e.g. Jeevaratnam, Msiza, Case & Fraser, 2001) have found that students tend to associate energy in particular

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contexts with the way energy is treated in certain courses, such as chemistry and physics. From the results of the study, it is clear that students provide different responses depending on the representation format of the diagnosis (i.e. open-ended question or pictorial questions). This finding suggests that the teaching and learning of the energy concept should involve multiple representations which can serve as useful visual tools to help students understand. In this way, teachers can foster students’ ability to conceive new situations and avoid any impression of dealing with a closed body of knowledge. Some researchers (e.g. Heuvelen & Zou, 2001) have found the multiple-representation method to be useful when teaching the work-energy processes in introductory college physics courses.

RECOMMENDATIONS FOR FURTHER RESEARCH Although identifying incorrect answers and ideas is a vital step in improving understanding, it is important that reasons for the incorrect ideas are understood. Thus, further research focussing on why students provide incorrect ideas is recommended. The present study revealed that many students could define energy as ‘the ability to do work’ but were unable to explain it as they were required to do. An in-depth analysis of how students interpret this textbook definition may be a potential area to investigate. Another suggestion would be one in which the terminology concerning energy and energy-related concepts is analysed. In particular, the researcher(s) would find out why students use phrases such as used up, lost, built up, produced or generated, when talking about energy. Perhaps, this would lead to a step further in which the researcher could consider the extent to which everyday language interferes in the understanding of energy. The science education literature has suggested that multi-modal representation (such as use of diagrams, factual statements or situational statements) is critical to understanding science (e.g. Hand et al., 2009; Prain et al., 2009). However, there has been little research to explore the enhanced cognition that occurs during the transformation from one representation to another representation. Therefore, further research is needed to determine why students provide different responses in different modes of representation. Several instances of these differences were imminent in this study especially where the students who agreed that the statement energy cannot be destroyed nor created was correct, contradicted themselves when they erroneously


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thought the statement when living things are active, they lose energy is correct.

CONCLUSION The main purpose of this study was to investigate students’ ideas about a range of energy-related concepts in biological context, amongst first-year South African biology students using a pencil-and-paper test developed by the researchers. The findings from this study elicited four major aspects. First, it was not possible to establish with certainty the extent of understanding of the concept of energy (tested in question 1) because students did not all follow the instructions for the question. That is, although students were asked to explain what energy meant, 44% of them gave the correct definition. However, because definitions are easily rotelearned, it became difficult to judge whether these students really understood the concept of energy. Second, whilst nearly all students recognized the statement energy cannot be created or destroyed to be correct (98%), many could not apply it consistently to other statements testing the same concept. Third, determining the sources of energy needed for metabolism in living organisms was interesting in a sense that whilst majority of the students (87%) correctly indicated that the energy needed by plants and animals for various metabolic processes is made available during respiration, some of these students showed incoherent understanding. For example, 55% of them erroneously indicated that the digestion is a process that provides energy needed for movement in animals, and 78% of the students erroneously believed that plants get the energy they require for their life processes (for example, growth) directly from the sun. Fourth, many students correctly indicated that energy is involved in the four diagrams depicting biological and non-biological phenomena (i.e. man playing soccer, growing potted plant, statue and the lion eating a dead zebra). However, 64% of the students erroneously indicated that energy is not present in a statue. These findings suggest that even if some students are able to define or explain what energy is, they may in fact not have a conceptual understanding of the concept. This was evident in this study with the energy conservation principle in which many students could not apply it to other situations. Furthermore, some answers which were wrong may simply reflect language problems and not conceptual problems, particularly in the 11 statements in which students were asked to indicate

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if statement was correct or incorrect and underline the word/phrase that made the statement incorrect and write-in the word/phrase that would correct the statement. The language problem as a confounding variable in the diagnosis of students’ ideas has been discussed by Clerk and Rutherford (2000, 715) when they stated that: Language problems do sometimes masquerade as misconceptions. This has serious implications for teaching. If a student is found to be answering questions incorrectly, it could be counter-productive to jump to conclusion that true misconceptions are held.

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