Middle School Students’ Understanding of Energy in Health and Fitness

Abstract

We used mixed methods to identify middle school students’ conceptions and misconceptions of energy in the domain of health and fitness. We selected a total of 24 middle schools from six school districts in a Southeastern state of the U. S. through stratified sampling. Students were first given a standardized knowledge test to establish their knowledge level membership in the domain of health and fitness. A sample of 291 students was selected from the 24 schools for semi-structured interviews on their understanding of energy sources for physical activities and consequences of energy surplus. Analysis of the interview data identified a variety of misconceptions on energy by grade and knowledge levels. Different conceptual change theories were adopted to form four themes to explain the identified misconceptions. We discussed pedagogical implications that may help address the misconceptions in and beyond the domain of health and fitness.

Introduction

As a concept that cuts across all science disciplines, energy is widely used in daily life (Chen et al., 2014). For instance, concepts of energy intake, energy expenditure, energy sources and energy balance/imbalance are critical for individuals to understand the role of dietary and lifestyle behaviors in personal health beyond physical and chemical sciences. Mastery of these concepts is critical for adolescents to understand the role of food and exercise in human life and daily living.

Helping students to acquire knowledge on energy in the domain of health and fitness contributes to their learning of energy in science at large. The Next Generation Science Standards (NGSS; NGSS Lead States, 2013) for high schools delineated that students are expected to “(c)onstruct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules” (p.105); and “(c)onstruct and revise an explanation based on evidence for the cycling of matter and flow of energy in aerobic and anaerobic conditions” (p. 65). Teaching the content also presents unique challenges to students and teachers. The concept of energy is omnipresent in all scientific fields. One of the ultimate goals for science education is to ensure students to realize that “ATP in biology, activation energy in chemistry and kinetic energy in physics are all the same energy” (Eisenkraft et al., 2014, p. 6). The students are expected to adopt energy as “an analytical lens that can cross disciplinary boundaries” (Chen et al., 2014, p.238). Also, there are “substantive differences in how the energy concept is used across discipline” (Krajcik et al., 2014, p. 358). The incongruity between energy’s cross-disciplinary universality and its domain specificity is another pedagogical challenge of teaching energy-related concepts. In each domain students need domain-specific scaffolds to schematize the concept of energy. As Quinn (2014) elaborated,

Chemists talk about bond energy. Nuclear physicists use the term binding energy. Biologists and earth scientists talk about chemical energy, or food and fuel as sources or stores of energy. Engineers talk about electrical and mechanical energy and about energy conversion (p.16).

Thus, teaching the concept of energy from a cross-cutting perspective (NGSS Lead States, 2013) would facilitate students to adopt a unique set of fundamental knowledge and principles about how energy works in each domain. The challenge of doing so is that transferring one set of conceptual principles from its domain to another domain may not always benefit but indeed undermine students’ learning. For instance, when apply energy conservation principle, a pivotal energy-related principle in environmental science, to the domain of health and fitness, it would be rational to choose sedentary lifestyle for energy saving purpose.

Teaching energy-related concepts in the domain of health and fitness requires teachers to adopt strategies to counter students’ intuitive conceptions they gathered, and continue gathering, from daily life experiences. Educational research has long confirmed that, one of the biggest challenges for science education is helping students to overcome or correct their original intuitive conceptions constructed from experiences (Vosniadou, 1994; Vosniadou & Brewer, 1992). From this perspective, the purpose of this study was to identify middle school students’ conceptions and misconceptions on energy in the domain of health and fitness.

Theoretical Framework

Conceptual change has been recognized as a powerful framework to inform pedagogical decision-making in science education (Vosniadou, 1994). Barner and Baron (2016) depicted conceptual change as a process of changing “a core set of innate mental representations which themselves are directly triggered by experience in the world” to “representations that are vastly more abstract than those found in core knowledge” (p.7). To explain this changing process, different theoretical frameworks have been developed. Vosniadou (1994) elaborated that in the process of conceptual change, learners gradually replace their intuitive conception, also called the naïve mental model, with a scientific conception. Such a process involves several stages, including mental model enrichment, model revision and radical reconstruction, to achieve the final objective. The challenge lies in the stages of radical reconstruction. Chi and Roscoe (2002) defined conceptual change as a process of eliminating misconceptions which are often resulted from ontological miscategorization – “when a concept that has been miscategorized into an ontologically distinct category” (Chi & Roscoe, 2002, p. 14). Thus, the challenge for conceptual change lies in facilitating the creation of new ontological categories and re-assigning concepts to the ontological category they belong to. Carey and Spelke (1994) recognized that conceptual change should be understood in domain-specific context, as each knowledge system has a distinctive set of core conceptual principles. Thus, the process of conceptual change should not be interpreted as “one mechanism by which conceptual change occurs” (Chinn & Samarapungavan, 2009, p.48) but many mechanism of conceptual changes varied by domain.

Various conceptual differences in different domains could pose distinctive learning difficulties for students. Chinn and Samarapungavan (2008) analyzed conceptual differences between prior knowledge and target conceptions across domains. They recognized that conceptual change can occur through multiple routes and mechanisms, and suggest educators to map domain-specific conceptual change through the following four identifiable components to facilitate learning (Chinn & Samarapungavan, 2009). They are (a) initial and final conceptions, (b) the trajectories of conceptual change, (c) the processes of conceptual change, and (d) the factors that inhibit or promote conceptual change (Chinn & Samarapungavan, 2009). Using these components could not only facilitate educators’ investigation of domain-specific conceptions and misconceptions by mapping the point of departure and ultimate learning goal for conceptual change, but also design domain-specific pedagogical strategies to overcome learning obstacles.

The Current Study

In this study, we intended to utilize prior knowledge data from a large, representative sample of middle school students to understand the patterns of their prior knowledge about energy-balanced living. We focused on the following research questions: (a) to what extent did middle school students mis-conceptualize the energy sources as related to health and fitness? and (b) what was the pattern of their conceptions and misconceptions about energy balance and energy-balanced living? The study may contribute to the theoretical understanding of conceptual change in the domain of health and fitness by clarifying the patterns of prior knowledge for developing effective teaching strategies.

Methods

This study was a part of a large-scale school-based health and fitness curriculum intervention project. The data in this study consisted of the baseline data that captured middle school students’ conceptualization of energy sources and consequence(s) of energy imbalance prior to receiving either the intervention or comparison curriculum. Both concepts are vital conceptual principles in the domain of health and fitness.

The state essential standards for health and physical education expect the concept of energy balance to be first introduced to students at 4^th grade. Through curricular spiral, the content with more depth is to be covered in 5^th, 6^th and 7^th grades. In 5^th grade, students are to be introduced why body needs energy – body needs energy for basal metabolism, lifestyle activity, and purposeful activity. Also at 5^th grade, students are expected to know the caloric density of macronutrients – fats carry nine calories, and carbohydrates and proteins carry four calories each per gram. The content about macronutrients are to be reviewed in 6^th and 7^th grades. At 6^th grade, whole grains are to be explained as an excellent energy source and as fiber-dense foods. Also at 6^th grade, foods that are rich in vitamins and minerals but with lower calories are introduced to students as healthy. At 7^th grade, the relationship between physical activity and caloric intake is expected to be introduced through data-drive approach. At 8^th grade, students are expected to interpret the Body Mass Index in relation to healthy weight, review the concepts of caloric intake and expenditure, and understand the three energy pathways. Throughout the later years of elementary schools and middle schools, the consequences of energy balance/imbalance, are to be taught to students repetitively.

Participants and Sampling

The curriculum intervention project was conducted with a random sample of 24 middle schools in a Mid-Atlantic state of the United States. The school sampling followed a stratified randomization procedure. First, based on the U.S. national school data (Snyder & Dillow, 2012), we stratified all the schools in the state that fell in the range of one-standard deviation of the mean of the school socioeconomic status measure (the rate of students who were eligible for Free And Reduced Meals, FARM %) and student academic performance measure (state standardized tests) to create a sampling pool. We then matched the schools in pairs by the measures and divided them into six exclusive brackets. Second, from each of the six brackets, two pairs of schools were randomly selected, then one in each pair was randomly assigned to the curriculum intervention (experimental) condition and the other the comparison (control) condition. The procedure created a sample of schools with diverse ethnicity, socio-economic status, and academic performance that represented the schools in the state. We selected from each school three to six students stratified by grade, gender, ethnicity, and body weight to provide the data. The selection achieved a sub-sample of 291 students (130 boys, 161 girls; 108 sixth graders, 92 seventh graders, and 91 eighth graders). Signed parental consent and students’ assent forms were received prior to data collection to meet the university IRB regulations.

Research Design

We employed both quantitative and qualitative approaches for this study. We first used a standardized testing approach to determine students’ knowledge about health and exercise science in general and energy-specific knowledge in particular. The test results provided a panorama perspective about their knowledge level in the domain health and fitness. The testing was followed by an in-depth interview with the students. Armed with the information of each student’s knowledge level, we devised a series of questions to allow them to further elaborate their understanding of energy and related concepts. In other words, we provided an opportunity for them to “think aloud” about their understanding to give us sufficient evidence to structure their individual conceptions (or knowledge schema). We then corroborated their conceptions by triangulating the evidence from the test and interviews.

The Knowledge Test

The standardized knowledge test, covering the domains of fitness principles, dietary choices, energy sources, healthy lifestyle and fitness categories, consisted of 20 questions for each grade. All the questions demonstrated acceptable levels of validity evidenced with difficulty index ranging from .45 to .60 and reliability with discrimination indexes greater than .40. An exemplar question for 6^th graders was “Teenagers like me need about calories each day.” The choices were (a) 500 (b) 1,000 (c) 1,500 (d) 2,000. A question for 7^th grade was “Fats are source of energy that our body needs to function.” The choices included (a) the essential (b) the secondary (c) the peripheral (d) not a. A question for 8^th grade was If I eat one fried chicken wing (225 calories), I should balance the calories out by jogging or walking roughly .The choices were (a) 2,500 steps (b) 4,500 steps (c) 6,500 steps (d) 8,500 steps. The difficult level of the test questions were gradually scaled up from mainly descriptive questions (6^th grade) to relational and reasoning (7^th and 8^th grade). The test items were uploaded to Qualtrics, an online survey platform, to generate a hyperlink. The test link was emailed to health and physical education teachers of the 24 participating schools. The teachers distributed the link to the students on the testing days and joined with researchers to monitor the testing in their respective schools’ computer lab or media center. Each correct answer was awarded a point of 1, incorrect a 0. The test results of the sub-sample of 291 students were extracted from the large data set for analysis along the interview data for this study.

The Interviews

The student interviews were guided by a set of pre-developed questions that were intended to facilitate their articulation. Because talking to a researcher is a rare occurrence for the students, we used stimulus texts to facilitate the interaction between the interviewer and the student (Törrönen, 2002). Such a strategy, also called graphic elicitation, can facilitate interviewees to connect the visual stimuli with the interview questions, and to extrapolate and construct their understanding (Crilly, Blackwell, & Clarkson, 2006). Each interview began with showing the student a drawing that depicted a young girl who is running, panting and sweating juxtaposed with a girl who is sedentary. The interviewer would then ask the student to identify the girl who would likely be experiencing a higher heart rate and physiological changes indicating higher energy expenditure. The interviewer then started with questions about energy sources for physical activities and followed with probes that focus on how energy fuels physical activities in general, and aerobic and anaerobic exercises in particular. The questions included “Where does energy come from?” “What does your body use to make energy?” “How does your body produce energy to do physical activities?” and “What different types of ‘fuels’ does your body use to support anaerobic and aerobic exercise?” For the topic of energy balance, the questions included, “If you do not use up all of the energy you intake each day, where did it go?” and “How does the extra fuel affect your body?”

Data Reduction and Analysis

The knowledge test was graded, and the scores were used as a measure for student’s knowledge level. Using the +/− 50% standard deviation split method (Rencher, 2002), we grouped the students into low - (n = 96), medium - (n = 105) and high - knowledge levels (n = 90). We used the knowledge level membership as a dimension in addition to the grade level to tabulate students’ interview answers. Because health education is a non-tested subject in the state, curricular pacing differs across schools. As a result, students’ knowledge in the domain of health and fitness does not necessarily progress along with grade level. Thus, it is necessary to establish a valid measurement of student learning progression in addition to grade level.

Transcribed interviews were imported to NVivo 12 plus for open-axial-selective coding (Patton, 2014). Open coding was used first to identify conceptions of energy sources and of potential consequences of energy imbalance. Based on students’ answers, the open coding process generated a large quantity of categorical codes. We then entered each student’s codes in the SPSS database along with his/her knowledge test score, knowledge level membership, and other demographic information such as gender and grade level. It allowed us to tabulate codes by the knowledge level membership and grade level.

The axial coding was conducted to bridge between the identified thematic threads and compare students’ conceptions and misconceptions across grade levels and knowledge levels. This process was characterized by repeated panel discussions and reconciliation of differences on major themes. The cyclic process continued until the themes were fully developed and verified with indisputable evidence. Theme verification was achieved through selective coding characterized by triangulating knowledge test results, interview results, and researcher discussions.

Results

In this section, we first present the descriptive statistics from the knowledge test, knowledge level grouping, and tallies of students’ answers to questions on energy sources then questions on the consequences for energy surplus. We present two categories of findings: Energy Sources: Where Does the Energy Come From? and Energy Balance/Imbalance: Where Does the Energy Go?

Knowledge Test Results and Grouping

The standardized test results revealed that the students were not knowledgeable about any topics of energy included in the knowledge test. The means of the percentage-correct scores for the 6^th (n = 108), 7^th (n = 92) and 8^th grade (n = 91) were 5.26 (SD = 2.06), 5.55 (SD = 2.06), and 6.04 (SD = 2.49), respectively. The results indicated a very low knowledge level across all three grades with a grand mean of 5.59 (SD = 2.22), meaning as a group they answered about 5.6% of the 20 questions correctly. The across-the-board low knowledge indicated insufficient scientific understanding of health and fitness knowledge. Table 1 shows the distribution of students by knowledge level and grade.

Table 1.

Knowledge Level Group Membership by Grade (N=291)

Membership	6th Grade	7th Grade	8th Grade	Subtotal
Low Knowledge	41	30	25	96
Middle Knowledge	40	36	29	105
High Knowledge	27	26	37	90
Subtotal	108	92	91	291

Energy Sources: Where Does the Energy Come From?

The responses to the question of “where does energy come from?” revealed a wide spectrum of misconceptions. The most frequently cited energy sources were: (a) foods (including “food” in a general way, specific foods, and micronutrients and macronutrients), (b) water and beverages, (c) oxygen, air and breathing, (d) body parts and/or organs, (e) exercise and/or training, and (f) sleeping, taking breaks and/or other sedentary activities (Table 2). The frequency of referring to these answers varied across knowledge level and grade level. In addition to the most frequently cited answers, a small number of students identified caffeine (n=2), Sun (n=5), warm-up activities (n=6), heart beat or heart pumping blood (n = 9), and sweating (n=12) as sources of energy respectively.

Table 2.

Energy Sources Named by Knowledge Groups and Grades

	Low (n=96) na / %	Medium (n=105) n / %	High (n=90) n / %	Subtotal
Foods b	53 / 55.21	66 / 62.86	69 / 76.67	188
Water and beverages	32 / 33.33	32 / 30.47	20 / 22.22	84
Oxygen, air & breathing	14 / 14.58	17 / 16.19	9 / 10.00	40
Body parts and/or organs	15 / 15.63	16 / 15.24	12 / 13.33	43
Exercise and/or training	17/ 17.71	18 / 17.14	5 / 5.56	40
Sleeping, taking breaks and/or other sedentary activities	8 / 8.33	8 / 7.62	8/ 8.89	24
	6th (n=108) n / %	7th (n=92) n / %	8th (n=91) n / %	Subtotal
Foods b	58 / 53.70	58 / 63.04	72 / 78.02	188
Water and beverages	30 / 27.78	27 / 29.35	27 / 29.67	84
Oxygen, air & breathing	13 / 12.04	13 / 14.13	14 / 15.38	40
Body parts and/or organs	22 / 20.37	13 / 14.13	8 / 8.79	43
Exercise and/or training	17 / 15.74	14 / 15.21	9 / 9.89	40
Sleeping, taking breaks, and/or other sedentary activities	10 / 9.26	6 / 6.52	8 / 8.79	24

^an represents cumulative frequencies by energy source types. For example, a student could be tallied three times when s/he named food, water, and heart as energy sources.

^bFoods include general response “food/s,” specific items such as “bread,” and nutrient groups such as “carbohydrates,” “fats,” and “protein.”

A tally of the codes on energy sources showed that the percentages of students who claimed no knowledge decreased as knowledge level increases (Table 3). A smaller percentage of students at the high knowledge level (7.78%) could not identify energy sources in the interview compared to 10.48% at the medium and 13.54% at the low knowledge level. The same trend is also evident with grade levels. There were 13 (12.04%) 6^th graders, 12 (13.04%) 7^th graders and six (6.59%) 8^th graders who could not identify energy sources for physical activities. We also found 68 (23.37%) students who identified something other than foods/food choices as energy sources.

Table 3.

Identified Energy Sources by Knowledge Groups and Grade (N=291)

	No Entry a	Foods b	Food+ c	Others d	Subtotal
Knowledge
Low	13 / 14%	20 / 21%	33 / 34%	30 / 31%	96 / 100%
Medium	11 / 10%	29 / 28%	39 / 37%	26 / 25%	105 / 100%
High	7 / 8%	41 / 46%	30 / 33%	12 / 13%	90 /100%
Subtotal	31 / 11%	90 / 31%	102 / 35%	68 / 23%	291/ 100%
Grade
Sixth	13 / 12%	23 / 21%	37 / 34%	35 / 33%	108 / 100%
Seventh	12 / 13%	30 / 33%	31 / 34%	19 / 20%	92 / 100%
Eighth	6 / 7%	37 / 41%	34 / 37%	14 / 15%	91 / 100%
Subtotal	31 / 11%	90 / 31%	102 / 35%	68 / 23%	291 / 100%

^aNo Entry: the number of the students who could not name anything as energy sources.

^bFoods: the number of the students who named foods as the sole source of energy.

^cFood+: the number of the students who named foods and other alternatives as energy sources.

^dOthers: the number of the students who named anything other than foods as energy sources

Overlapping identification.

Also shown in Table 3, we found prevalent overlapping identification of energy sources occurred in the students who identified both food(s), correctly, and other alternatives, incorrectly, as energy sources. There were 33 students (34.38%) at the low knowledge level, 39 students (37.14%) at medium and 30 (33.33%) at high knowledge level identified both foods and other alternatives as sources for energy. Similar results were shown across grade levels. There were 37 (34.26%), 31 (33.70%), 34 (37.36%) students from 6^th, 7^th and 8^th grade respectively demonstrated overlapping identification of energy sources.

For instance, one 7^th grader at the high-knowledge level was able to identify protein and vegetables as energy source, but still claimed water as a major source. He tried to be inclusive by explaining, “To have energy, first you got to eat healthy. Drink water and eat vegetables every day, so you save your energy. You have to get the right protein in the morning.” Another 7^th grader at the medium-knowledge level claimed that in addition to foods, her body extracts energy from oxygen and heart, “energy is from oxygen, foods and your heart, all of them!” Another 8^th grader at the high-knowledge level explained that, energy is extracted from “us eating foods and exercising more often.”

Among the students who identified foods generally as energy source, some were able to identify various food choices and nutrients as sources for energy (Table 4). Students at higher knowledge levels were more likely to identify macronutrients (carbohydrates, proteins, and fats) as their energy sources. However, some of these students also included micronutrients, such as minerals and vitamins, in their lists. A 7^th grader at the medium-knowledge level claimed, “My body could use iron, zinc and protein for energy.” In the same vein, an 8^th grader at the high-knowledge level identified carb, proteins and vitamins as major sources for energy. Students at lower knowledge levels showed a stronger tendency to identify vitamins and particular food choices, such as vegetables and fruits, as sources for energy.

Table 4.

Tally of Specific Food Choices and Nutrients by Knowledge Group

	Low	Medium	High	Subtotal
Protein	5	9	21	35
Grain	0	2	1	3
Vege and fruits	14	12	10	36
Egg	0	1	0	1
Carbohydrates	1	4	17	22
Vitamins	9	2	4	15
Milk/Calcium	2	2	5	9
Fats	2	2	4	8
Minerals	1	3	5	9

Healthy Indulgent Food Choices

For students who identified foods, nutrients and food choices as sources for energy, the ones at higher knowledge levels were more likely to identify major macronutrients, especially carbohydrates and proteins, as sources for energy than their counterparts at lower knowledge levels (Table 4). However, we also found that many students, across all knowledge levels, identified foods with low caloric and/or high fiber density as major energy sources. They believed that fruits, vegetables, healthy snacks and sport drinks give them energy for physical activities or the best sources of energy. For example, a 7^th grader at the low-knowledge level claimed “broccoli, corn and fruits” as his source of energy. An 8^th grader at the medium level articulated, energy comes from fruits and vegetables, “… if I was going to run a marathon, I’d probably eat a lot of fruits and vegetables.”

Within the group of students who were indulged to healthy food choices, a total of 13 students clearly pointed out that junk foods do not provide energy for physical activities, and energy is exclusively from healthy foods, sports drinks and snacks. An 8^th grader at the low-knowledge level pointed out that foods are the source of energy but also added “energy only comes from nutrients, like eating green and healthy foods and not from eating junk food all the time.” Another 6^th grader at the low-knowledge level insisted that energy is from vegetables not from junk food and asserted, “It says, you go out and eat a lot of junk food, then your body probably is not going to use it to exercise, because you’ve eaten so much.”

Overall, for the students who identified foods as source for energy, we only found a few who could articulate relatively accurate and scientifically sound understanding of food choices in relation to physical activities. Some were able to identify protein-rich foods as good for muscular strength development and complex carbohydrates as good for cardiovascular fitness training. A 7^th grader at the high-knowledge level identified the foods of complex carbohydrates as good choices for providing sustaining energy for a long period of time, “it has something to do with complex carbohydrates … Like grains and brown rice, you should eat those before a big game because they take longer to digest. They have more fiber.” Another 6^th grader at high-knowledge level correctly pointed out the right dietary choices for different activities, “You kinda want to eat like wheat bread and stuff like that, so you will have a good energy for running. And when you’re lifting weights and trying to get stronger, protein helps build muscle and get stronger.”

To summarize, most students were at the level of merely identifying what they thought would be energy sources without specific and scientifically sound knowledge. This is manifested in their inability to determine with certainty that carbohydrate, fats, and protein are primary energy sources for human life and physical activity. When conceptions are solely established on experiences without scientific guidance to guide mental operations (von Glasserfelt, 1995), the conceptions are likely to stay at the intuitive level (Brewer, 2008). In contrast, a few at the high knowledge level were able to connect foods (particularly macronutrients such as carbohydrates, fats, and proteins) to specific physical activities. This finding suggests that these students began to form conceptions to explain the role of the energy from different sources in relation to physical activities that may demand different ways of energy supply. The one-on-one correspondence between energy and physical activity association is still not scientifically sound, as the energy metabolism is rather a sequential pathway than discrete processes. However, such a conception carries the potential of advancing towards scientific conception.

Energy Balance/Imbalance¹: Where Does the Energy Go!?

Extra energy/calories, especially in the form of excessive body fat, will result in a variety of health consequences. The result shows, 84 students, approximately 30% of the entire student sample, identified weight gain, overweight, obesity, losing shape, low fitness, and cardiovascular diseases as the consequences of energy surplus (Table 5). Unlike their answers to the previous question on energy sources, overlapping identification was not observed in the students’ responses to this question. The students in higher grades and at higher knowledge levels were more likely to recognize the health-damaging consequences of energy surplus. Many students at the middle and high knowledge levels could provide specific examples to elaborate their answers. A 7^th grader at the high knowledge level pointed out, “you could gain more and more weight. And then like most people die from that in heart attacks mainly.” An 8^th grader at the medium-knowledge level elaborated the consequence, “I would add weight by (gaining) fat, and it can affect your body by clogging up your arteries or blood stream.” For another instance, a 6^th grader at the medium knowledge level elaborated, if you do not spend all energy, “by gaining weight, you’re probably not gonna be able to run and play as much.”

Table 5.

Identified Consequences for Energy Surplus by Knowledge Group and Grade (N=291)

	Low (n=96)	Medium (n=105)	High (n=90)	Subtotal
No knowledge	40	40	22	102
Fat, overweight, obesity, low fitness and chronic diseases a	21	29	34	84
Energy stored for future use	14	12	10	36
Fatigue and cramps	12	10	11	33
Energy wasted or disappeared	3	4	6	13
Hyper, excitement and insomnia	5	8	6	19
Nothing	1	2	1	4
	6th (n=108)	7th (n=92)	8th (n=91)	Subtotal
No knowledge	44	38	20	102
Fat, overweight, obesity, low fitness and chronic diseases a	23	23	38	84
Energy stored for future use	14	8	14	36
Fatigue and cramps	12	10	11	33
Energy wasted or disappeared	3	6	4	13
Hyper, excitement and insomnia	10	5	4	19
Nothing	2	2	0	4

^aThis is the only conception consistent with scientific consensus.

The results also indicated that 105 (36.08%) students of the total sample had developed a wide spectrum of misconceptions about the energy balance or imbalance. For example, a few students considered that “weight gain” was resulted from muscle mass increase. One 6^th grader at the low-knowledge level elaborated, “It (energy) becomes like weight or something. It makes you a little bit bigger. It would probably make your muscles a little bit bigger or fatter.” Another 6^th grader at the medium-knowledge level directly pointed out that extra energy in the body could “build up muscle in you.”

A close examination of the interview data indicated that 44 (40.74%) 6^th graders, 38 (41.30%) 7^th graders and 20 (21.98%) 8^th graders admitted that they could not specify the consequences for energy surplus and the relation between energy surplus and health. Similar distribution was also found across knowledge levels: 40 (41.67%), 40 (38.10%) and 22 (24.44%) students at low-, medium- and high- knowledge level respectively admitted that they had no knowledge about the questions. Four students claimed that there was no consequence for energy surplus. The interview data on the topics revealed a range of misconceptions related to energy imbalance. The four misconceptions below were the most frequently cited by the students.

Extra Energy Stored for Future Use

A total 36 students (12.37%) pointed out that the unused energy, or the surplus, would be stored in the body for benefits. With probes, they further explained that the stored energy could be used in near or distant future when necessary. An 8^th grader at the low-knowledge level explained, “The unused energy will be stored in the body until the next day for me to use.” Another 8^th grader at the high-knowledge level shared a similar opinion, “it (stored energy) would give me extra energy, like for the next day.” A 6^th grader at the low-knowledge level was positive about the long-term usage of stored energy by using backup battery as a metaphor, “I think that it (unused energy) stores…I was talking about it (the body) can hold energy and store it for like a backup, kind of like a backup battery.” Another 6^th grader at the medium-knowledge level believed that stored energy would give individuals an advantage, “You would be more energetic than someone who has used up all their energy.” An 8^th grader at medium-knowledge level carefully reasoned using life-threatening scenarios,

Because it (stored energy) makes you enduring like if you had a plane crash or something in the wild and you have to survive or something you had to fight off animals and stuff, you’d be strong and stuff. You could climb a mountain or something just because you have it (stored energy).

Extra Energy Leads to Physical Discomfort (Fatigue and Cramps)

A total of 33 students (11.34%), 12 (12.50%) students at low, 10 (9.52%) students at medium, and 11 (12.22%) students at high knowledge level, shared the thought that energy surplus can lead to various physical discomfort, characterized by bodily fatigue or muscle cramping. When describing bodily fatigue, the students rarely relied on scientific concepts but settled with their personal judgmental concepts derived from their life experiences. They used phrases such as feeling lazy, feeling sleepy, or being not motivated for anything to describe their feelings. An 8^th grader at the medium-knowledge level pointed out that energy surplus would make people unwilling to do anything and lazy. Another 8^th grader at the same level described, “I think it (energy surplus) makes you all tired and sleepy and not want to do nothing”. A 6^th grader at the high-knowledge level described the consequence of energy surplus as feeling “weak and yucky.” A 7^th grader even claimed, “(energy surplus would make people) don’t want to move, don’t want to walk, and don’t even want to step foot anywhere if you haven’t burn all of it (energy surplus).”

Another frequently cited discomfort led by energy surplus is muscle cramping. A 6^th grader at the low knowledge level implied, “If you are not exercise every day and use up all energy, your legs might like cramp.” A 7^th grader at the medium knowledge level was sure that, “if you don’t get your exercise to burn the energy, the next day once you eat and you exercise again, you might start feeling cramps in your arms and your legs and your stomach.” Another 7^th grader at the low knowledge level believed that energy surplus would lead to muscle injuries. An 8^th grader at the low knowledge level asserted that energy surplus, resulted from overeating and sedentary lifestyle, would lead to constipation and stomach cramp.

Extra Energy Dissipated (Wasted or Disappeared)

A total of 13 students (4.5%) believed that unused extra energy would leave the body dissipated, as waste or just disappear. A 6^th grader at the low-knowledge level explained, “It (energy) will go away, and you won’t have a lot more left.” A 7^th grader at the low-knowledge level claimed that “the energy will be digested and dissolved. It’s not in your body anymore.” An 8^th grader at the high-knowledge level pointed out, “the (extra) energy is gone because you use energy for sleeping.” Another 7^th grader at the high-knowledge level articulated:

Because when we have a lot of energy that we don’t use, it just sits in there. It’s like wasting something you don’t need. Because if I sit outside doing nothing and I knew that I can run longer but I sit in my room to play video game. That means I have wasted some energy that I could have used to help my body be healthier. It may stay there and be wasted overtime. And it’s bad.

A 7^th grader at the medium-knowledge level shared the thought, “I think it (extra energy) is dissolved. Because if I do a soccer game and then I don’t use all my energy, like I’ll just rest; I think that it (energy) just goes down and makes me slow down my heart rate a little bit.”

Extra Energy Leads to Hyper, Excitement and Insomnia

A relatively small number of the students (n=19, 6.53%) across all the knowledge levels believed that energy surplus could excite people and the euphoria might lead to insomnia or feeling of restlessness. For instance, a 6^th grader at the high knowledge level described, “It (extra energy) makes me feel like happy or something like that. It can boost somebody up or something like that.” An 8^th grader at the medium knowledge level stated, “By having energy leftover, I guess harder to sleep or not sleep as long.” Another 8^th grader at the low knowledge level claimed, “It could be dangerous because if you have so much energy, it can bump up your heart rate really fast and it can make you go to the hospital.” Also, a 6^th grader at the medium knowledge level provided a personal account of having surplus energy, “I’m not sure. Usually for me, I get all new energy (when I have energy leftover) … I want to go outside and play right away. Like when you drink coffee then you’re all jittery, that’s how I am.”

Discussion

Through this study, we tried to answer two questions: (a) to what extent did middle school students mis-conceptualize the energy sources as related to health and fitness? and (b) what was the pattern of their misconceptions about energy balance/imbalance and energy-balanced living? The findings showed that (a) the students held a spectrum of misconceptions about the sources of energy that energize human life and physical movement. (b) most students had difficulty to explain the function of energy and the relationship between energy surplus and health consequences. In the following sections we theorize the findings with four identified themes to explain the factors that lead to the widely presented misconceptions. The themes are (a) Prevalence of Intuitive Conceptions: Overreliance on Lived Experiences, (b) Discourses Embedded in Synthetic Models, (c) Science as Alternatives: Explanatory Coexistence, and (d) Out of the Place: Negative Knowledge Transfer Across Domains.

Prevalence of Intuitive Conceptions: Overreliance on Lived Experiences

The results of this study confirm previous findings that the life-experience based intuitive conceptions are the initial point to conceptualize abstract concepts on energy in health and fitness (Chi, 2008). The overreliance on life experiences resulted in various forms of intuitive conceptions. For instance, several students identified organs or body parts, such as brain, heart and legs, as sources of energy by simply reasoning from their experience that physical activity involves body parts. The reasoning might include some basic elements of scientific knowledge (Thagard, 1992): the heart and lungs play a vital role in physical activity and the functions can be felt directly through heart beats and heavy breathing. These direct life experiences may have prevented the students from establishing an in-depth scientific conception that the heart and lungs are not energy source but merely transport the energy elements and facilitate the biochemical reactions of generating the energy to power physical activity. Similar evidence includes that a large number of students identified water and beverages (including sports drink); oxygen, air and breathing; sleeping, taking a break and/or other sedentary activities, as energy sources. Among all the identified categories, the category for sleeping, taking a break and/or other sedentary activities has the lowest counts. All these misconceptions were based on their personal experiences of taking a deep breath, taking a break, or drinking water to ease discomfort induced by intensive physical activity.

Our findings seem to support the theoretical proposition that easily accessible life experience would make the deepest conceptual impression to serve as the basis for strong misconceptions (Brewer, 2008). Because these personal life experiences are easily accessible, they function as reinforcements for the misconceptions, which in turn are likely become strong, robust, and legitimate theoretical foundation for future use (Vosniadou & Brewer, 1992 & Vosniadou, 2012). The cyclic reinforcement seems to be at work for the students as well. The misconceptions of energy sources were likely to be reinforced each time the students participated in physical activity. The strengthened misconceptions then became embodied to serve as a platform for other misconceptions such as energy availability and energy surplus. This can also be clearly evidenced in the students’ responses on the consequences of energy surplus. Many identified personal experiences of muscle or stomach cramps as results of too much energy in the body. If we expect our students to become scientifically literate, these misconceptions must be confronted and addressed effectively to help students conceptualize energy beyond the limitations of life experiences.

Discourses Embedded in Synthetic Models

The process of conceptual change requires bridging relevant life experiences and to-be-learned knowledge in a delicate way for learner develop a necessary synthetic mental model (Vosniadou et al., 2008). In reality, classroom is not the only location where students receive “knowledge.” On a daily basis, students are exposed to both scientific and non-scientific discourses. Particularly, “the word energy has entered everyday discourse, with a meaning that is related to, but rather different from, the scientific one” (Millar, 2014, p. 187). As a result, the unscientific daily use of “energy” to describe emotional and psychological being acts as a barrier to learn scientific concepts about energy (Liu & Park, 2014; Jin & Wei, 2014).

From the students’ responses to energy sources, two students identified coffee/caffeine as energy source, with one of them described the “jittery” feeling from consuming coffee to obtain energy. Furthermore, a considerable number of students (n=19) described feeling hyper, excitement and insomnia as the consequences of energy surplus. In other words, their direct feeling of “being energetic” “excitement” and “enjoyment” was interpreted to be the source of energy. Also, a small number of students believed warm-up activity as the source of energy, as it offers them an “energy” boost. The evidences pointed out a confusion led by the ambiguity of language and the pedagogical challenge to help students differentiate how energy is used in daily and scientific discourses.

The result of this study also indicates that the loose use of energy-related language on health-related subject matters contributed to students’ confusion of feelings and conditions such as being healthy (Jin & Wei, 2014). In the current study, a large number of students who regarded fruits and vegetable, water, sport beverage, vitamins, and minerals and heavily advertised “healthy snacks” as energy sources due to the perceived benefits to health. Fats and carbohydrates, two of the macronutrients and major sources for energy, were to various degrees stigmatized as offering bad or no energy. The finding could be attributed to the learning materials in health classes that students were exposed to about nutrition, such as the health consequences of excessive intake of foods that are high on refined carbohydrates or fats and the health benefits of consuming low fat high protein foods.

There are arguments in the literature that adolescent learners built their misconceptions by synthesizing information from schools and popular media, especially commercial advertisements (Moje, Ciechanowski, Kramer, Ellis, Carrillo, & Collazo, 2004). The daily exposure to commercial discourses deliberately promote perceived healthiness of certain foods, such as “healthy snack” “sport drinks” and “energy drinks” using active human images to create and reinforce the message of “active people eat (advertised foods/drinks) for energy.” With an extensive exposure to the media, a student might integrate the information with what was just learned in class to form a synthetic conception. Excessive consumption of these products could be understood as providing energy for physical activity (Provencher, Polivy, & Herman, 2008). Using the synthetic mental models to help students establish the scientific mental models is the goal of teaching. When the synthesis takes place with misinformation, the consequence can be a synthetic mental model even farther away from the scientific conception. Although we did not collect data on the media influence, the responses about sport drinks and other commercial products from the students’ responses appear to imply such influences.

Science as Alternatives: Explanatory Coexistence

Recent research indicates that scientifically literate adults could simultaneously hold scientific and intuitive conceptions (see also Gelman, 2011; Legare, Evans, Rosengren, & Harris, 2012). Defining the phenomenon as explanatory coexistence, Shtulman and Lombrozo (2016) consider it as a rather stable stage in conceptual change process, in which “early-developing concepts coexist with later-developing concepts because both types of concepts remain useful for predicting and explaining the natural world, albeit in different circumstances or for different purposes” (p. 53). Such a phenomenon alludes a theory in contrast to traditional conceptual change theories. Shtulman and Lombrozo (2016) elaborated, classic conceptual change theories all suggest a tension-laden process of replacing intuitive conceptions (which they called folk theories) with often the scientific conceptions. For explanatory coexistence, the intuitive conception, if not regress or replaced by scientific conceptions, could continue to evolve along the progression of scientific conception (Potvin & Cyr, 2017). Such a phenomenon also pose a question: Under what circumstance, would explanatory coexistence prevail?

The results of this study confirm that explanatory coexistence in middle school students. Across the knowledge levels, students who identified foods or even macronutrients as energy sources, also identified oxygen, body parts and/or organs, water and beverages, and resting and/or sleeping as sources for energy. Moreover, cross both grade levels and knowledge level levels, explanatory coexistence manifests itself consistently – approximately 35% of the student sample demonstrated overlapping conceptions (see Table 3). In contrast, students’ responses to the question on the consequence of energy surplus indicated an absence of explanatory coexistence. No student who identified overweight, obesity, low fitness, and chronic diseases as the consequence for energy surplus believed that energy saved for benefits, wasted energy, excitement, various cramps, and fatigue as coexisting consequence. The contrast provided an opportunity for us to understand the conditions under which explanatory coexistence prevails in terms of the energy-balanced living concepts.

The different degrees of explanatory coexistence embodied in students’ answers for energy sources and consequences of energy surplus could be due to the logical relationship between the scientifically correct concepts and the intuitive concepts. Specifically, the more logically antithetical to each other, the less likely for students to form explanatory coexistence that includes scientific and intuitive concepts. In other words, the students’ responses to the questions of energy source, either scientific or intuitive, are more logically compatible to each other than their responses to the questions on consequences of energy surplus. For example, for students who endorsed the notion that energy surplus leads to undesired health consequences, it is logically incompatible to also believe that energy surplus would give them an advantage by saving energy for immediate or long-term future use. Conceptual change theory suggests that when learner encounters new beliefs and notes inconsistencies or contradiction, an engagement in conceptual change starts (Carey, 1999). If the new encounters fail to present an evident and direct threat to the rationality or coherence of pre-existing intuitive conception, and when the intuitive conceptions held utilitarian value in explaining the natural world (Shtulman & Lombrozo, 2016), the conceptual change process could enter the unique stage of explanatory coexistence.

Conceptual change literature has suggested that, by presenting students a direct conflict between intuitive and scientific conceptions and guiding them to solve the conflict, they are more likely to embrace the scientific conceptions eventually (Hewson & Hewson, 1984; Limón, 2001). It challenges teachers to be familiar with students’ prior knowledge, explore cognitive architecture of knowledge construction, anticipate the potential learning constraints, and craft conceptual conflicts to overcome learning constraints.

Out of the Place: Negative Knowledge Transfer across Domains

Teaching energy as a crosscutting-domain concept requires teachers to break boundary of various domains and help students form a unifying, yet disciplinarily diverse and sophisticated understandings of the concept (Seeley, Vokos & Minstrell, 2014). It requires students to achieve knowledge transfer by applying the knowledge across domains. Often, cross-domain knowledge transfer is considered a hallmark of true learning (Barnett & Ceci, 2002). However, when we expect students to construct flexible models to empower cross-domain knowledge transfer, we also should be prepared to tackle misconceptions and confusion resulted from cross-disciplinary incompatibility. For instance, recent research indicate that elementary school students believed that they can turn on the “energy saving mode” by engaging sedentary or low-intensity activities and explained their rationale by conceptualizing human bodies as cars and machines (Authors, 2019). Characteristics of overgeneralizing prior knowledge (Schwartz, Chase & Bransford, 2012), the phenomenon defined as negative knowledge transfer, describes learners transfer learning to a situation where it is inappropriate to do so (Ross, 1987).

Across all three knowledge levels, we found students who transferred the principles of energy transformation, conservation, degradation and dissipation learned from science to the domain of health and fitness. The energy conservation principle states that the total amount of energy in the universe is constant, and energy can be stored in different forms. When the principle is transferred to the domain of health and fitness, some students believed that the energy surplus would be properly conserved for future use. Such a knowledge transfer overlooks the detrimental health consequences of depositing energy surplus as visceral fat by perceiving human body as energy storage device such as a battery as students described. Some students transferred their understanding of energy degradation and dissipation from science to construct their understanding of the consequences for energy surplus. When explaining the consequence of energy surplus, they used words, including “lost,” “dissolved,” “disappeared,” “gone,” and “wasted,” to describe how surplus energy is dissipated and degraded overtime. The conception is problematic scientifically because energy cannot be created or destroyed – it only moves between one place and another place, between objects and/or fields, or between systems (NGSS Lead States, 2013). Certainly, some students mistaken the amount of energy consumed by human bodies to sustain basic metabolic functions as the energy they lost involuntarily rather than moved to another place in the biological sphere of the human body. A small number of students identified Sun as the source of energy to fuel human movement. Although photosynthesis serves as the basic energy source for virtually all organisms on Earth, directly transferring it to the domain of health and fitness indicates a disengagement of disciplinary context. The witnessed negative knowledge transfer in understanding energy in the health and fitness domain reminds us of the potential challenges in helping students to achieve the goal of using energy as an analytical lens that transcends disciplinary boundaries.

Pedagogical Significance of the Study

The objective of the conceptual change is for students (a) to understand macronutrients as the sources for energy, the consequences of energy surplus as body weight gain, obesity, and various chronic diseases, and (b) to master skills of making scientific decisions, as related to physical activity and diet, for energy balance and optimal fitness. The first important message to educators is that we should not overly rely on the results of standardized tests to understand learner misconceptions. Many students who scored at the medium and even high knowledge level still held considerable misconceptions. Furthermore, even for students who could successfully identify foods as sources of energy, their conception could be subjected to explanatory coexistence.

The second important message is that educators need information about patterns and potential causes of misconceptions. This challenges researchers to expand inquiries to identify prevalent patterns and latent causes for misconceptions, such as explanatory coexistence embodied through cross-identification and negative cross-domain knowledge transfer. In addition, the findings of this study raise the empirical significance to evaluate the logical relationship between scientific and intuitive concepts to prevent explanatory coexistence and negative cross-domain knowledge transfer. We emphasize this need as a critical step for the teaching force to systematically address overwhelmingly diverse misconceptions and various factors that impede conceptual change.

The most prominent challenge for students to accomplish conceptual change is intuitive conceptions derived from and validated constantly by daily experiences. To effectively address the challenge, instructional practices should focus on raising students’ awareness of the necessity for establishing alternative conceptual categories, which are distinctive from their subjective sensation of physical activities, for potential ontological shift (Chi & Roscoe, 2002). In this process, teachers should focus on helping students establish and differentiate ontological categories to understand energy for human body and fitness. The results also showed that synthetic models that students generated to understand energy are connected to the loose use of “energy” in daily life, especially those used in describing feelings of “being energetic” “excitement” and “enjoyment” and consumerism related health discourses. Thus, teachers should use scientific vocabulary in instruction to help student differentiate scientific energy discourse and the language in daily life that contributes to the formation of misconceptions.