Education
Energy and Matter: Differences in
Discourse in Physical and Biological
Sciences Can Be Confusing for
Introductory Biology Students
Laurel M. Hartley, Jennifer Momsen, April Maskiewicz, and Charlene D’Avanzo
Biology majors often take introductory biology, chemistry, and physics courses during their first two years of college. The various and sometimes
conflicting discourse about and explanations of matter and energy in these courses may contribute to confusion and alternative conceptions (those
that differ from scientific consensus) in biology learners. An important area of biology education research—students’ alternative conceptions—has
produced a lengthy list of alternative conceptions related to students’ understanding of matter and energy flow through biological systems through
processes such as photosynthesis and cellular respiration. By synthesizing the research literature and conducting interviews of science faculty members, we have identified similarities and differences in matter and energy discourse and teaching in these different science disciplines. This study
can help biology instructors recognize and appreciate the ways in which instructors present concepts related to energy and matter in their courses
and alter their discourse and teaching practices to promote learning and minimize confusion among their students.
Keywords: matter, energy, discourse, biology teaching
I
ra Glass’s quotation (see below) reflects a common naive conception that matter and energy are synonyms.­
Although at a subatomic level, this statement has truth (i.e.,
E = mc2), biology students who articulate this idea are not
thinking subatomically; they actually believe that energy
“turns into” matter during processes such as photosynthesis
and respiration (Hartley et al. 2011). This example shows
how students in introductory physics, chemistry, and biology
courses may ­experience discourse (how instructors explain
concepts) about matter and energy in completely different
ways. In the present article, we explore such differences in
discourse among physicists, chemists, and biologists at an
introductory college level to help biology instructors begin
to bridge students’ conceptual understandings of matter and
energy across these science courses.
“Matter and energy are different versions of each
other. And while you can convert one into the other,
they cannot be ­created or destroyed.”
—Ira Glass, host of This American Life, 31 May 2002
Matter and energy are core concepts throughout science
curricula in high school and college (College Board 2009,
AAAS 2011). The College Board (2009) identified matter and
energy as a unifying concept that should help high-school
students build connections among science disciplines. At the
college level, Vision and Change in Undergraduate Biology
Education (AAAS 2011) identified movement and transformation of energy and matter as a core concept underpinning
biological literacy. Such repeated exposure to matter and
energy in the physical and biological sciences should reinforce
biology undergraduates’ understanding of both. However,
research indicates that many biology students provide explanations suggesting that matter or energy can disappear, suggesting that matter can become energy and vice versa, and
that fail to properly account for atoms during transformation
processes (Wilson et al. 2006, Hartley et al. 2011).
Understanding how matter and energy are transformed in
biological systems is critical to understanding the core content
taught in introductory biology courses (table 1). We suggest,
therefore, that biology educators consider the entire learning landscape experienced by students who may be ­taking
introductory biology, physics, and chemistry simultaneously.
Helping introductory biology instructors understand the
BioScience 62: 488–496. ISSN 0006-3568, electronic ISSN 1525-3244. © 2012 by American Institute of Biological Sciences. All rights reserved. Request
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488 BioScience • May 2012 / Vol. 62 No. 5
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Table 1. Framework relating typical introductory biology curriculum to the conservation of matter and the conservation
of energy.
Matter
Energy
Topic
Concept
Terminology
Concept
Terminology
Photosynthesis
Matter is converted from
carbon dioxide and water
into glucose.
Calvin cycle, light and dark
reactions, plant growth, net
primary production
Energy is converted from
light energy to chemical
energy.
Transmembrane proton pumps,
plant growth, energy stored in
plant biomass
Transformation
Molecules are transported
through living organisms,
broken down and converted
into other molecules as
part of growth and biomass
allocation.
Anabolism, catabolism,
consumption or eating,
biomass allocation and
growth, herbivory, predation,
sequestration
Energy is transferred as
matter is transformed from
one chemical to another.
Biosynthetic pathways, growth,
biosynthesis, energy flow
through food webs, energy
pyramid
Oxidation
Matter is oxidized to carbon
dioxide and water during
respiration.
Krebs cycle, glycolysis,
heterotrophic respiration,
autotrophic respiration,
decomposition and decay,
net ecosystem respiration
Energy is transferred as
matter is broken down into
simpler molecules and some
energy is converted and
released as heat.
Electron transport chain,
respiration, movement,
temperature regulation,
decomposition and decay,
atmospheric warming
different discourse and applications of matter and energy
among science disciplines may improve their ability to
address student conceptions about matter and energy, which
will ultimately lead to improved student learning.
Our goals in this article are to compare how introductory
biology, chemistry, and physics textbooks define and contextualize matter and energy; to provide a useful, compact
synthesis of research on student conceptions of matter and
energy; and to compare and contrast the contexts and discourses used by instructors who teach introductory biology,
chemistry, and physics.
Methodology for the text review, literature review,
and faculty-member interviews
Textbooks contain the context, definitions, and explanations for concepts in a discipline. To achieve our first goal,
we reviewed popular college biology, chemistry, and physics
textbooks (table 2), focusing on the definitions of energy and
matter in their glossaries or texts and on concepts related to
energy and matter within their indices.
Next, we surveyed published biology, chemistry, and
physics education research concerning students’ conceptions
of matter and energy. Given the depth of this research area
(nearly 4000 published articles since 1969), we do not present an exhaustive review. Rather, we detail common themes
concerning student conceptions of energy and matter that
emerged from our broad reading of the literature.
Finally, to better understand the classroom discourse surrounding energy and matter, three of us (each a biologist)
conducted 30–60-minute semistructured interviews of one
or two college chemistry and physics faculty members (n = 5
chemists and n = 4 physicists) at our institutions to uncover
the language, contexts, and scale commonly used in their
explanations of phenomena related to matter and energy
(see the supplemental material, available online at http://
dx.doi.org/10.1525/bio.2012.62.5.10, for the interview questions). Some interview questions were adopted from a study
designed to expose biology students’ alternative conceptions
about energy and matter (Hartley et al. 2011), whereas
www.biosciencemag.org others were based on our literature review. We recorded
and transcribed the interviews, and then each author independently read the transcripts to look for themes common
among the faculty-member answers, with particular attention paid to commonalities and differences in the discourse
used by the faculty members of various disciplines. We then
discussed the themes that emerged from our readings of the
transcripts, reconciled our interpretations, and returned to
the transcripts to ensure that all of the data were consistent
with these themes. Although this limited set of interviews
cannot represent all physical-science faculty members, it did
uncover several differences in how science faculty members
teach about energy and matter at the introductory level.
Our findings are divided into three sections: the textbook
analysis, the synthesis of research on student conceptions,
and the interview findings.
Definitions and presentations of energy and matter
in introductory physics, chemistry, and biology
textbooks
The textbooks’ treatments of matter differed markedly from
those of energy. Of the 10 textbooks we surveyed, 8 defined
energy, and all of them included energy in the index. Only
four textbooks defined matter, and five included matter in
the index (table 2).
Six textbooks (five biology, one chemistry) described
energy as “the capacity to do work” (table 2). Three biology
texts included the idea that energy can promote or cause
change, and two (one biology, one chemistry) described
energy in relation to the movement of heat. We see several
problems here. First, several words (e.g., capacity, work, heat)
are lexically ambiguous (Lemke 1990)—that is, they have
common, colloquial meanings that may confuse students
or conflict with scientific meanings. Furthermore, abstract
terms such as work may confuse students. For example,
will introductory-level students understand the work done
when a concentration gradient is maintained across a cell
membrane or when amino acids condense to form proteins
(Wood-Robinson 1985)?
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Table 2. Textbook definitions and index-term usage of matter and energy.
Physics
Chemistry
Biology
Definition of
matter
No definitions found in glossary or introductory
chapters.a,b,c
Anything that occupies space and
has mass.d
The material of the universe.e
Anything that takes up space and
has mass.f,g
Composed of atoms.g
Definition of energy
The concept of energy has grown and changed
with time, and it is not easy to define in a
general way just what energy is.a
The term energy is so broad that a clear
definition is hard to write. Technically, energy is
a scalar quantity associated with the state (or
condition) of one or more objects… Energy is
a number that we associate with a system of
one or more objects.c
The capacity to do work.d,e
To cause heat flow.e
The capacity to do work.f,g,h,i
To cause change.f,i,j
To cause heat flow.h
Associated with a system (chemical
or physical).i
Index terms and
concepts related to
energy
Potential energy, kinetic energy, mechanical
energy, thermal energy, conservation of energy,
relativity, storage, transport
Chemical energy, electrical
energy, heat, internal energy,
kinetic energy, potential energy,
thermal energy, bond energy,
heat, conservation of energy,
transfer of energy, internal energy
Chemical energy, heat, kinetic
energy, thermal energy, elements,
budgets, catabolic pathways, free
energy, energy flow in ecosystems,
laws of thermodynamics, energy
processing, torpor, energy transfer
between trophic levels
Index terms and
concepts related to
matter
Antimatter, dark matter, energy released by,
particle nature, wave nature, building blocks of
States of matter: solid, liquid,
gas; quantum nature
Elements, compounds
Knight 2008.
Serway and Faughn 1999.
c
Halliday et al. 2011.
d
Tro 2010.
e
Zumdahl and Zumdahl 2007.
f
Campbell and Reece 2007.
g
Raven et al. 2008.
h
Freeman 2011.
i
Sadava et al. 2011.
j
Brooker et al. 2008.
a
b
The contexts in which energy appeared in the textbook
indices varied. All of the textbooks addressed various forms
of energy (e.g., potential, kinetic, chemical, thermal; table 2).
In the biology textbooks’ indices, there was a clear focus on
movement (e.g., energy flow or transfer through ecosystems)
and transformations of energy (e.g., laws of ­transformation).
In contrast, similar discourse was not apparent in the physics and chemistry textbooks’ indices. Furthermore, only
two biology indices listed conservation of energy or laws of
thermodynamics, whereas all of the physics and chemistry
textbooks did. Therefore, on the basis of the textbook indices, one might conclude that the conservation of energy is
an unimportant concept in biology. We suggest instead that
the conservation of energy is an explicit topic in physics and
chemistry texts but is more implicitly discussed in biology.
Matter was defined concisely in four of the textbooks (two
biology and two chemistry texts) as either the material of the
universe or anything that takes up space or has mass (table 2).
A single biology text identified matter as composed of atoms.
Overall, these definitions are broad, devoid of context, and
rely on the students’ existing scientific understanding. As a
result, such abstractions may lead to memorization instead
of problem solving. Furthermore, as with energy, numerous
lexically ambiguous terms (e.g., material, space, mass) may
impede student understanding.
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The context in which the concept of matter is taught was
difficult to discern from the sampled textbooks. Matter was in
five of the textbooks’ indices as forms or states of matter (i.e.,
elements, dark matter, antimatter, wave nature). We found
this curious, since chemistry and physics students learn
about atoms and molecules—all forms of matter. Perhaps
the textbooks’ authors and editors viewed matter as a general
umbrella term that they did not need to define. This is problematic, because the law of conservation of mass or matter is
a unifying scientific principle that students should be able to
apply to biology, physics, and chemistry. They may find this
difficult if they do not recognize that atoms and molecules
are both types of matter, for example.
Common student alternative conceptions about
energy and matter
There is a wealth of research on student conceptions of
energy and matter in biology, chemistry, and physics. The
following summary of this work is designed to help instructors better appreciate common alternative conceptions and
therefore to more effectively teach about energy and matter
in biological contexts.
Energy. Students’ conceptions about energy are wide ranging
and differ in their sophistication. First, energy is often used
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in everyday discourse in a nonscientific way (Brook 1986,
Millar 2005, Mohan et al. 2009), which leads to its being a
lexically ambiguous term. Some students say that they “have
a lot of energy,” equating the term with vigor and believing
that energy is related to fitness and strength (Brook 1986).
A second common idea is that energy is a currency that can
be bought or sold (Cachelin et al. 2010). Students also think
energy can be used up or lost (Hartley et al. 2011) and may
justify this with examples of dead batteries and empty fuel
tanks (Ross 1993). As a final example, students often view
energy as something that enables organisms to carry out
a function, with objects either needing or having energy
(Mohan et al. 2009).
These broad and vague ideas limit students’ ability to
understand energy transformation and conservation during
biological conversion processes such as respiration and photosynthesis (Anderson et al. 1986). Many do not apply the
law of conservation of energy at all and assume that energy
can be “used up” (Kesidou and Duit 1993, Hartley et al.
2011). Others do not account for the degradation of energy
or energy transformations or conflate matter and energy,
assuming that they can be interconverted (Wilson et al.
2006, Hartley et al. 2011). For example, many college biology
students do not recognize energy in a form that is not biologically useful (e.g., heat as a product of cellular respiration)
and therefore misunderstand energy degradation (Hartley
et al. 2011). Another widespread alternative conception is
that energy is stored in the bonds of substances and released
when these bonds are broken—rather like a fluid leaking
out of a broken pipe or egg (Ross 1993). In fact, energy has
to be supplied to break bonds rather than its being released
when they break. Misunderstanding the nature and role of
energy can lead to simplistic one-dimensional explanations
of biological systems.
Matter. Biology instructors can learn a good deal about
students’ alternative ideas about matter from chemistry,
physics, and biology education research. For example, many
studies identify students’ alternative conceptions about gases,
including that gases can disappear, that they are weightless,
or that they have little weight (e.g., Cetin et al. 2009). These
ideas have implications for biology instruction, because the
conservation of matter is fundamental to students’ understanding of many metabolic processes. For example, Hartley
and colleagues (2011) quoted a college student talking about
photosynthesis: “[carbon dioxide] does add weight but not
a lot, [because] gas [does] not have much mass [and does]
not take up much of the weight.” Students who ignore or
misunderstand matter conservation for gaseous reactants
and products may not comprehend how cellular respiration
results in a loss of carbon dioxide from organisms or that the
atmosphere is the carbon source in photosynthesis.
Chemistry education research has exposed many alternative conceptions about the particulate nature of matter. For
instance, Adadan and colleagues (2009) asked chemistry students to draw solids, liquids, and gases at the submicroscopic
www.biosciencemag.org level; over half drew solids as continuous and homogenous
(no particles), in contrast to liquids (large particles) and
gases (small particles). Such conceptions may limit students’
understanding of molecular movement and transformations
in biological systems. These ideas exist because of challenges
in interpreting what we can and cannot see. Although faculty
members intuitively make conceptual shifts between observable and microscopic phenomena (Maskiewicz 2006), students struggle to understand the interactions between atoms
and molecules, which are not visible, and then to apply
these ideas to everyday macroscopic phenomena. Even some
upper-level chemistry students hold naive ideas about the size
of atoms (Haidar 1997). A third level of comprehension—
symbolic representations of atoms and molecules in equations and models—also challenges students’ conceptual
understanding of matter (Gabel 1999).
Finally, many studies describe students’ application of
agency in natural phenomena: Events happen because they
“need to” or are caused by an outside force (e.g., Tamir and
Zohar 1991). A related idea is that things have a natural
and predetermined way of being. Such ideas are evident in
descriptions that “water causes salt to dissolve,” water exists
because hydrogen “needs an electron in its outer shell, and
oxygen needs two,” and “when you put two things together,
they will always react” (Taber and Garcia-Franco 2010).
Ascribing agency may prevent students from thinking about
processes and mechanisms. If plants photosynthesize and
animals respire out of “need,” students may find no reason
to think through the underlying mechanisms.
Findings from the interviews with faculty members
Interviews with faculty members who teach introductory
chemistry or physics revealed differences in discourse and
contexts concerning matter and energy. As was expected,
physical scientists, like biologists, draw on the laws of conservation of matter and energy in their courses. However, we
identified three distinct differences in how matter and energy
were discussed and applied: the boundaries that the faculty
members drew around systems, how the faculty members
traced matter and energy within systems, and the distinction
between matter and energy.
Drawing boundaries around systems. In introductory biol-
ogy courses, living systems are examined across a range of
scales—subatomic, atomic, molecular, subcellular, cellular,
organismal, ecosystem, and global—and related topics may
well be presented at different points in the course. For
instance, what students learn about carbon fixation and
the Calvin cycle may be the basis for their understanding of
plant function and whole-ecosystem metabolism. However,
recognizing the appropriate scale at which to reason about a
biological process is difficult for students (Maskiewicz 2006,
Wilson et al. 2006, Hartley et al. 2011). In contrast, science
instructors easily trace matter and energy across scales. For
example, ecologists considering questions about carbon
dynamics in ecosystems routinely think about carbon in
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elemental and molecular form, in cells, in organisms, and
within the ecosystem as a whole. We propose that the automatic nature of this reasoning can explain why instructors
may not recognize that this is a challenge for their students.
The boundaries that biologists consider with respect to
energy and matter are defined by particular systems (e.g.,
body, ecosystem) with which we are dealing. Biologists
might trace energy “flow” into a plant cell as radiant energy
assimilated (and therefore biologically useful) and energy
that leaves the cell in organic compounds (also useful).
Energy not used to do metabolic work may not be accounted
for. Although biology teachers recognize that unaccounted
energy is not “lost,” a surprising number of introductorylevel biology students believe that energy can truly be “lost”
(Hartley et al. 2011), as opposed to its being not lost but
biologically unavailable.
In contrast, physicists may be more explicit about the
conservation of energy, perhaps because physicists’ range
of focus extends from the subatomic scale to the universe.
Indeed, three of the four physicists that we interviewed
explicitly defined a system’s boundaries when discussing
energy. Physicist 1 said that “energy is conserved, and then
I guess it’s a matter of thinking of what are the bounds of
your system?” When discussing energy, physicist 2 said that
he pays careful attention to “what your boundaries [are] and
what comes in and what goes out.” Physicist 3 responded
similarly to an interview question about matter and energy
cycling in a rainforest (box 1, quotation 1).
Four of the five chemists that we interviewed also explicitly defined system boundaries, but here, chemical reactions
at the molecular scale defined the boundaries. In response to
the rainforest question, chemist 1 explained that in a rain­
forest, her scale of interest was at the level of chemical reactions within that system (box 1, quotation 2). Interestingly,
when discussing energy, all of the interviewed chemists
mentioned that the boundaries encompass the universe: For
instance, chemist 2 said, “but we do talk about heat and work
and energy being lost, and the system gaining it and losing it,
the universe gaining it and losing it around it.” Nevertheless,
the problems and tasks that students engage when considering energy are at the scale of a chemical reaction (box 1, quotation 3). In summary, all five chemists specifically referred
to very large and very small scales and to energy transfer
across these scales and frames of reference, and they were
careful to define the forms of energy (e.g., heat, chemical)
that they were describing. Again, this small sample cannot
represent all chemists; rather, these instructors show what it
means for instructors to carefully describe and define terms
and system boundaries related to energy and matter.
Finally, an interview question focused on recycling of
­carbon versus the “loss” of energy in an ecosystem resulted in
lengthy and at times confusing discussions about the terms
recycling and lost. When talking about a rainforest, a biologist
would not consider energy to be recycled, because after energy
is transformed into heat, living systems can no longer use it
for metabolic processes. In contrast, the physicists equated
492 BioScience • May 2012 / Vol. 62 No. 5
tracing energy with energy recycling. Three of the chemists
said that they would not use the term recycled at all when
discussing energy or matter (box 1, quotation 4). The term
recycled then, seems to imply different meanings for these
disciplines, because scientists focus on different aspects of a
system. This illustrates how students might be confused by
the use of words in biological and physical science classes.
Tracing matter and energy within the system. In accordance
with the quotations above, we found that all four physics
interviewees emphasized the movement of energy into and
out of a whole system, whereas the five chemists placed more
importance on the movement of energy within the system.
In contrast, the biologists tended to focus on processes that
facilitate the transfer of energy in living systems. Therefore,
students in introductory chemistry, biology, and physics may
be asked to account for details of the energy of systems with
varying degrees of specificity.
The physicists that we interviewed typically focused on
energy movement, with discourse about energy as moving from or toward something (box 1, quotations 5 and 6).
Furthermore, all four physicists traced energy entering and
leaving a system; the details of energy transformations inside
the system were less important. For example, when he was
asked how glucose in a grape provides the energy to move
your finger, physicist 3 explained that the specific mechanisms were not important to him (box 1, quotation 7).
In contrast, all five chemists were primarily interested in
mechanisms and in tracking the energy of reactants and products throughout their transformation. Chemist 3 said, “Your
reactants versus your products are going to have some level
of potential energy… if the reactants have a higher potential
energy and… [the] products have a lower potential energy,
there’s a release in energy.” In biology courses, students are
rarely asked to account for energy in a quantifiable way or to
trace energy in an explicit way, and the chemists were eager
to illuminate some of the errors of biologists regarding this
issue, especially in regard to the concept of chemical bonds
(box 1, quotation 8). The idea that certain chemical bonds
store large amounts of energy, such as phosphate bonds in
ATP (adenosine triphosphate), has been criticized for nearly
30 years (Wood-Robinson 1985) but still persists in biology courses. All five chemists also critiqued the incorrect
idea that “breaking bonds gives off energy” (e.g., respiration
releases the energy held in the high-energy bonds of organic
molecules). Chemist 1 suggested that discourse and a lack of
energy-accounting practices in biology might perpetuate this
conception, whereas chemist 3 shared an excerpt from a text
illustrating this point (box 1, quotation 9).
In our interviews, it was clear that tracing matter within a
system was just as important an issue for chemists as tracing
energy. The chemistry faculty members explicitly required
students to quantitatively trace atoms and molecules. One
interviewee suggested that biologists’ tendency to black-box
(or fail to explain in detail) enzymatic reactions of biological processes may well confuse students in regard to tracing
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Box 1. Interview responses regarding student conceptions of matter and energy.
Drawing boundaries around systems
Quotation 1. Physicist 3: “[In the rainforest], a physicist might talk about… the boundaries of that system. So if it’s a closed system,
if it’s this rainforest,… all the energy in there is recycled within the system.”
Quotation 2. Chemist 1: “The boundary meaning the entire rainforest… you’re talking about the ecosystem?… When [sic] we give
problems, individual problems for students to solve, and we actually have them calculate how much heat is given off by a system. When
we refer to a system, it is something very small.”
Quotation 3. Chemist 3: “You could compare the energy of the reactants and the products, and then, so if something—let’s say the
reactants are of higher energy and then the products are of lower energy, there’s that change and so that is maybe given off as heat.”
Quotation 4. Chemist 3: “When we’re talking about energy or matter, we don’t use the word recycled. We’re talking more in a context
of overall, so energy is, you know, not created or destroyed, so it’s conserved, transferred from one form to another.... Really, in the big
scheme of things, when we’re talking, ‘energy is conserved’ it’s like in the universe, really.”
Tracing matter and energy within the system
Quotation 5. Physicist 3: “I think of energy in terms of transfer.... On the level of what we talk about in physics most of the time, the
energy contained in an entity is transferred to some other entity or state. Thermal energy. Heat transfer. You have to have a gradient
for energy transfer.”
Quotation 6. Physicist 2: “And in a system, if energy leaves or somehow disappears, [we say] ‘Oh, let’s track down where that energy
went,’ and then we’ll define that as kind of another form of energy.”
Quotation 7. Physicist 3: “So I’d probably say, well, the glucose has energy and the ATP [adenosine triphosphate] has energy. And
something happened in between [that] transferred that energy. And I… don’t really care about the mechanism.… All I’m concerned
about when thinking about energy is that the energy here got transferred to the energy there. Probably it wasn’t 100%. Nothing’s ever
100%. So something happened, but that’s the flow of energy.”
Quotation 8. Chemist 2: “So one of the biggest misconceptions in chemistry [is that] breaking bonds gives off energy. That’s so wrong.
Energy comes flying out when you form bonds. Wrong! You are breaking bonds in glucose, putting energy in, but then in the formation of carbon dioxide and water, you’re losing energy, energy’s released.… It’s the formation of a more stable system that transfers the
energy. So the energy of glucose is released when the carbon dioxide and water are formed.... It’s just the difference in energy between
carbon dioxide and water, and [that between] glucose and oxygen. Reactions are coupled in a molecular way.”
Quotation 9. Chemist 3: “Scientists often say that energy is stored in chemical bonds or in a chemical compound, which may make it
sound as if breaking the bonds in the compound releases energy. For example, we often hear in biology that energy is stored in glucose
or in ATP. However, breaking a chemical bond always requires energy. When scientists say that energy is stored in a compound, or that
a compound is energy rich, it means that the compound can undergo a reaction in which weak bonds break and strong bonds form,
releasing energy. It is always the forming of chemical bonds that releases energy.” (Tro 2011, pp. 388–389)
Quotation 10. Chemist 2: “When you go from ATP to ADP [adenosine diphosphate], and you lop off a phosphate.… So I think it’s
a black box, just ATP goes to ADP and then you get a phosphate and then you get energy… but… P for us is phosphorus, it’s not a
phosphate.”
Conflating matter and energy
Quotation 11. Physicist 3: “As E = mc 2, now we’re talking about kind of a special situation in physics. So it’s not something I think
necessarily applied to every day life. So, while it is true that there’s an equivalence between matter and energy, in a biological context,
matter can’t become energy.”
Quotation 12. Physicist 1: “Within the context of chemistry and biology, matter and energy are two separate things... [but that’s not]
true when you’re dealing with nuclear processes or high-energy physics processes, particle physics.”
matter (box 1, quotation 10). Chemist 2’s argument here
is that P represents a phosphorus atom in chemistry, not a
phosphate group. In this way, biologists may be confusing
students who are learning how to follow atoms through biological mechanisms and across organizational scales.
Conflating matter and energy. Our last finding from the inter-
views returns us to Ira Glass’s quotation. From a biological
www.biosciencemag.org perspective, matter and energy are distinct; matter cycles
through cells, organisms, and ecosystems, whereas energy
may flow through these systems and degrade. However, each
of us has experienced introductory-level biology students
who tell us that matter and energy are interchangeable,
invoking E = mc 2. We originally assumed that the belief
originated in a physics class, but interviews with physicists
led us to another hypothesis: that students get the idea of
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E = mc2 from popular media such as This American Life or
from everyday conversations. From a physicist’s perspective,
although matter can be created from energy at a small scale
(e.g., particle physics), matter and energy are not interchangeable at the cellular or organismal scale (box 1, quotations 11 and 12). Students’ confusion ultimately results from
their lack of understanding of higher-energy physics and the
critical importance of scale in this particular case.
difficult to relate different types of symbolic representations
of molecules (such as molecular formulas and shapes) to one
another, for example. Validated concept inventories like this
are useful tools to help faculty members recognize especially
problematic aspects of students’ understanding of energy
and matter and to assess approaches, such as active teaching, that are designed to improve understanding (D’Avanzo
2008).
Instructional interventions
How can biology instructors help introductory-level students navigate such differences in the discourse and conception of energy and matter? Several suggestions have been
proposed by science educators to promote students’ scientific
understanding of matter and energy and their application of
that understanding.
Energy as an abstract concept is very difficult to teach
and learn, which leads to debates about how energy should
be taught in early grades through college (Millar 2005). For
instance, Kesidou and Duit (1993) recommended teaching the concepts of energy degradation (energy becomes
less usable) and energy conservation together. Our textbook
review suggests that energy degradation is emphasized less
than energy conservation. Solomon (1985, p. 169) recommended adding “there is the same amount of energy at the
end as at the beginning” to the phrase “energy can never be
created nor destroyed.” Here, the “same as” phrase is meant
to cue students to account for energy. Certainly, teaching
students to routinely account for energy would be valuable.
There are also debates about introducing energy qualitatively
or quantitatively (Duit 1987, Millar 2005). Warren (1982)
argued that energy should be introduced from the start
as an abstract mathematical concept, because qualitative
treatment makes energy seem like an invisible, intangible
substance that can flow from place to place. Others see qualitative treatment as a useful way of simplifying a difficult idea
(Millar 2005).
The many studies about students’ preconceived ideas
about matter have led to a good deal of research on possible
interventions. Visualization—asking students to represent
their understanding visually—has been a fruitful area of
research. For example, Harrison and Treagust (1996) studied students’ sketches of atoms, which included models like
solar systems, single and multiple orbits, and electron clouds
that differed in size by orders of magnitude. This research
led to the recommendation that instructors provide opportunities for students to draw their conceptions. The use of
computers to help the students better visualize microscopic
phenomena is an exciting area of research in chemistry (e.g.,
Cetin 2009). Finally, there is a large amount of literature on
conceptual inventories in the physical sciences—researchbased sets of questions designed to expose students’ alternative conceptions. For instance, Birk and Kurtz (1999) used
a two-tier diagnostic test (each multiple-choice question
required a brief explanation) on covalent bonding and structure and showed that even some graduate students found it
Critical lessons and opportunities for faculty
members
In general, we found both similarities and differences regarding contexts and discourse practices among the three disciplines with respect to matter and energy. Instructors in
all three disciplines applied the laws of thermodynamics to
constrain ideas about what is possible and not possible, but
whether the laws of thermodynamics are an explicit part of
the course varied among them. We found that the language
or discourse used and the system boundaries discussed were
fundamentally different among the disciplines. For example,
in chemistry class, a student may implicitly be required to
draw boundaries around a molecular reaction, whereas in
physics, the boundary might be the entire universe, and in
biology, the boundary might be the body of an organism or
an ecosystem. Explicitly understanding the boundaries of
a system has a direct influence on how far students choose
to trace matter and energy and whether they see matter
and energy as being conserved. Differences in discourse
and boundary delineations among the disciplines are rarely
explained to students.
We also found that many of the science textbooks that we
surveyed were not organized in a manner that parallels or
facilitates the teaching of core concepts for biological literacy,
which includes an understanding of the pathways and transformations of matter and energy. Indeed, although textbooks
are valuable collections of fundamental knowledge within
a domain, they usually do not illuminate the interrelationships between biology, chemistry, and physics. The simple
and concise nature of textbook definitions of matter and
energy, for example, support rote memorization but do little
to facilitate a systems approach to thinking about solutions
to scientific problems.
Our findings lead to several critical lessons and opportunities for biology instructors. First, we must recognize
that students walk into our classrooms with a wide range of
alternative ideas about energy and matter that we might not
anticipate. Biology faculty members can promote student
learning by being precise about our language as we explain
concepts that involve matter or energy. In doing so, we need
to be aware that language that is lexically ambiguous carries
multiple and often conflicting meanings for our students.
Such language, instead of clarifying difficult concepts, may
cause further confusion. Teachers may also explain to students how biologists account for and describe energy and
matter in contrast to how physicists and chemists do so.
As a final suggestion, instructors often use analogies and
494 BioScience • May 2012 / Vol. 62 No. 5
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Education
metaphors as tools to explain complex or abstract concepts,
with the intention of helping students gain understanding
by mapping difficult ideas to a familiar analog (Duit 1991).
However, this approach can lead to misrepresentations
and misunderstandings. For example, Venville and Treagust
(1997) explained how biological analogies can be a doubleedged sword: beneficial in some cases or leading to students’
alternate conceptions in other cases.
Research shows that students do not transfer prior knowledge across disciplines or even across scales within the same
discipline (e.g., from a single cell to an entire organism;
Maskiewicz 2006). Because the scale at which we reason
guides our discourse (i.e., what we say explicitly to our students and what we do not say), we propose that issues with
scalar reasoning are a root cause of some students’ erroneous
reasoning about matter and energy. A student taking courses
in the three disciplines could be studying energy, for example,
at scales ranging from the subatomic to the universe and
everything in between. Therefore, we believe that increasing
instructor awareness of the differences in how biologists,
chemists, and physicists reason about matter and energy can
help students leverage and integrate prior knowledge, which
would lead to greater understanding.
Our own scientific conceptions of the natural world
are often obvious to us: We understand where the system
boundaries lie, we can identify the components that make up
the system, we understand how those components interact,
and we can reason across scales of time and space (Ben-Zvi
Assaraf and Orion 2010). In short, biologists are expert systems thinkers. At times, we may forget that students are just
beginning to think and reason about systems. Systems thinking is far from trivial to learn and to teach (Hmelo-Silver
and Azevedo 2006), but current calls to reform introductory
biology explicitly include systems thinking as a core concept
for biological literacy (AAAS 2011), and therefore, we should
teach our students to think about energy and matter from a
systems perspective.
Ultimately, we ask ourselves what the correct approach
to teaching matter and energy is in an introductory ­biology
course. In response, we encourage biology instructors to
communicate with instructors in physics and chemistry
who teach introductory courses, so that common contexts
can be identified and shared with students. Courses such
as “Integrated Science” at Princeton and the “Bridging the
Disciplines with Authentic Inquiry and Discourse” curriculum at Michigan State University recognize the importance of
instructors’ working across disciplinary boundaries to foster
students’ abilities to transfer ideas across courses. Although
we recognize that integrated curricula are not feasible at
every university, simply discussing our courses and identifying common contexts could support a more integrated
understanding of matter and energy for our students.
Acknowledgments
This project was supported by a catalytic minigrant awarded
to the authors as part of a National Science Foundation
www.biosciencemag.org Research Coordination Network Grant (DBI-0840911) and
is covered by Institutional Review Board file no. SM11111
at North Dakota State University. This project was also
influenced by National Science Foundation Division of
Undergraduate Education award nos. 0919992, 0920186, and
0127388. We thank the anonymous faculty members who
agreed to be interviewed for this research.
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Laurel M. Hartley ([email protected]) is an assistant professor
of integrative biology at the University of Colorado Denver whose research
interests are in ecology and biology education. Jennifer Momsen is an assistant
professor of biology at North Dakota State University, in Fargo. Her research
is focused on undergraduate learning of biology. April Cordero Maskiewicz is
an associate professor of biology at Point Loma Nazarene University, in San
Diego, California, whose research is focused on teaching and learning in biology.
Charlene D’Avanzo is a professor of ecology in the School of Natural Sciences
and director of the Center for Teaching and Learning at Hampshire College, in
Amherst, Massachusetts. Her current scholarly activities are in faculty-memberdevelopment research.
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