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3
Learning About Evolution:
The Evidence Base
B
iological evolution is a difficult concept to learn, as several people at
the convocation emphasized. It involves complex biological mecha-
nisms and time periods far beyond human experience. Even when
students have finished a high school or college biology course, there is
much more to learn about the subject.
The difficulty of teaching evolution both complicates and invigo-
rates research on evolution education. To present what is known and not
known about the teaching and learning of evolution—which is a standard
feature of convening events organized by the Academies—Ross Nehm,
associate professor of science education at Ohio State University, gave an
overview of the research literature on evolution education and then talked
in more detail about his own research.
THE EVIDENCE BASE
The literature on teaching and learning about evolution is extensive.
In 2006 Nehm reviewed 200 of more than 750 papers published thus far
about evolution education, identifying both strengths and limitations
of the approaches taken in those studies (Nehm, 2006). This literature
demonstrates that the general public, high school students, undergradu -
ates, biology majors, science teachers, and medical students all have low
levels of knowledge and many misconceptions about evolution (Nehm
and Schonfeld, 2007). Furthermore, as with other areas of science, many
of the same misconceptions persist in all of these populations. “They don’t
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26 THINKING EVOLUTIONARILY
go away,” said Nehm. “Whatever instruction is happening at early levels,
it’s not ameliorating the problems that we have.”
In education, the only way to make robust causal claims is through a
randomized controlled trial (RCT), but no such trials have been conducted
for evolution education. “If you want to make causal claims, there is no
causal literature to refer to.”
Fortunately, other research tools can be used with educational inter-
ventions to draw conclusions that can guide policy. A group receiving
an intervention can be compared with a group not receiving the inter-
vention. Interventions can be done without a comparison group—for
example, by looking at a group before and after an intervention. Survey
research can yield associations, although survey research cannot deter-
mine whether these associations are causal. Finally, case studies, inter-
views, and other forms of qualitative research can reveal new variables
and possible associations.
Nehm’s 2006 review of the literature found no intervention studies
with randomized control groups, 6 intervention studies with comparison
groups, and 24 other studies that employed various intervention tech -
niques. Also, some of the interventions were quite brief—just one to three
weeks—a period during which substantial changes are unlikely to occur,
given the difficulties of teaching evolution. One conclusion is obvious,
Nehm said: “We need to do some randomized controlled trials to see what
works causally in terms of evolution education.”
Nehm also pointed out that documenting learning outcomes is criti-
cally important in education research. According to the report Know-
ing What Students Know: The Science and Design of Educational Assessment
(National Research Council, 2001), “assessments need to examine how
well students engage in communicative practices appropriate to a domain
of knowledge and skill, what they understand about those practices, and
how well they use the tools appropriate to that domain.” Yet most tests
today, including those that dominate biology curricula, assess isolated
knowledge fragments using multiple choice tests. Students may be learn -
ing about evolution, “but if we can’t measure that progress, we can’t show
that what we’re doing has any positive effect. So we need assessments
that can measure the way people actually think.”
The problems caused by inadequate metrics are particularly obvious
in the literature on teacher knowledge of evolution, Nehm said. Only five
intervention studies exist, and three of them assess teacher’s knowledge
of evolution using a multiple choice or Likert scale test (Baldwin et al.,
2012). This lack of careful metrics “is really concerning,” said Nehm. Evo -
lution assessments must be developed that meet quality control standards
established by the educational measurement community, or robust claims,
causal or otherwise, cannot be made.
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27
LEARNING ABOUT EVOLUTION: THE EVIDENCE BASE
In summary, research has established key variables that should be
investigated and many possible beneficial interventions. But the research
literature on evolution education lacks robust, causal, generalizable
claims relating to particular pedagogical strategies and interventions. It
also lacks measurement instruments that meet basic quality control stan -
dards and capture authentic disciplinary practices. Finally, the research
lacks consistent application of measurement instruments across different
populations. “This is a call to action,” said Nehm. “We need to gather and
do a national randomized controlled trial of some of the most likely and
agreed upon variables and test their causal impact on students’ learning
of evolution.”
NOVICE TO EXPERT REASONING
In his own research, Nehm and his colleagues have been studying
how different groups, from novice to expert, think about problems.1 Using
performance-based measures in which research participants are asked to
solve evolutionary problems, they have looked at 400 people—including
non-majors who have completed an introductory biology course, students
who have completed a course in evolution, students who have completed
an evolution course as well as more advanced coursework, and a group
of biology Ph.D. students, assistant professors, associate professors, and
full professors (Nehm and Ha, in preparation).
The study measured people’s ability to explain evolutionary change
across a variety of contexts, not through multiple choice questions. In
general, this technique revealed many more gaps in evolutionary under-
standing than would simpler assessments. For example, students have a
harder time explaining evolutionary change (in writing or orally) than
recognizing accurate scientific elements of an explanation when presented
in a multiple choice test (Nehm and Schonfeld, 2008). Or, as Nehm put it,
knowing the parts and tools needed to assemble furniture does not mean
that you can build it. Students may have a lot of knowledge about evolu-
tion but not be able to use that knowledge to create a functional explana-
tion. “This is a tough competency,” explained Nehm. “If you asked any
of your students, and I encourage you to do this, ‘Can you explain how
evolutionary change occurs?’ you will be startled at their inability to
articulate their understanding because they are never asked to do that.”
In addition, people have a tendency to mix naïve and scientific infor-
mation together in their explanations. Naïve ideas include, for example,
the notions that the needs of an organism drive evolutionary change or
1 A summary of the general research on differences between novices and experts can be
found in National Research Council (2000).
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28 THINKING EVOLUTIONARILY
FIGURE 3-1 Misconceptions decrease with educational level but never entirely
disappear (left), while mixed models of evolutionary change remain as common
in advanced biology majors as in non-majors (right). The vertical scale on the left
measures the numbers of key concepts and misconceptions used by respondents,
while the vertical scale on the right measures the percentage of respondents using
different kinds of explanatory models. SOURCE: Nehm and Ha, in preparation.
that putting pressure on animals will cause them to evolve. The mixing
of naïve and scientific ideas is difficult to measure with multiple choice
tests, but open response explanations can reveal the relative contributions
of each category of information.
Of 428 people—107 from each group—the experts (the combined
group of Ph.D. students, assistant professors, associate professors, and
full professors) knew more key concepts and had fewer misconceptions
(Figure 3-1). Some Ph.D. students still have naïve ideas about evolution,
and occasionally a professor, although that was uncommon. People learn
more about evolution as they take more courses, but a surprising number
do not get rid of their misconceptions.
Moreover, as shown in Figure 3-1, up to 25 percent of the advanced
majors who have taken an evolution course and other advanced courses
still construct mixed models of evolutionary explanations that com-
bine naïve and scientific ideas. The use of exclusively scientific models
increases with educational level, but this use never gets above 60 percent
of students in Nehm’s research. Furthermore, many students have only
naïve ideas, although this percentage declines with educational level.
SEEING BENEATH THE SURFACE
Research shows that novices tend to get tripped up by surface fea-
tures of problems, such as the context, format, or details of a problem,
rather than grasping a problem’s underlying structure. They think that
similar problems framed in different ways are actually different problems,
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29
LEARNING ABOUT EVOLUTION: THE EVIDENCE BASE
whereas experts see the similarities that are not apparent on the surface of
those problems. Nehm and Ridgway (2011) applied this analysis to evolu-
tionary biologists and to non-majors who had taken an introductory biol-
ogy course and found the same thing. For example, elements of natural
selection were linked consistently by experts but haphazardly by novices.
An especially intriguing finding was that students tend to draw on
different misconceptions in trying to solve different types of problems. In
problems involving plants, animals, or bacteria, for example, their miscon-
ceptions tend to differ based on the type of organism they are being asked
to consider. Thus, in teaching evolution, the types of misconceptions that
teachers think they are tackling are correlated with the kind of problem
they give students. For example, even though teachers may think they
are describing a problem involving natural selection, a particular surface
feature of the problem may keep students from recognizing the connec -
tion. Likewise, in assessments, the type of misconception being assessed
is correlated with the type of problem students are trying to solve. “That’s
a big implication,” said Nehm. Students see natural selection in a cheetah
and in a bacterium as completely different processes. This is one way in
which they glue new information onto preexisting naïve ideas.
The importance of surface features has received almost no attention in
evolution education, Nehm observed. Introductory biology textbooks use
a variety of contexts but never alert students that bacterial resistance to
antibiotics is no different from the many other examples of natural selec -
tion being described. “We never help students see those parallels.” Even
after completing an evolution course, only 50 percent of students have
“expert-like” perceptions of evolutionary problems. As students progress
through biology, their courses do little to help them reason across cases.
Novices’ Thinking About Evolution
What are the problems that novices have in thinking about evolu-
tion? People have many different kinds of knowledge, including con -
ceptual resources, analytical resources, and factual resources. According
to traditional models of problem solving, people draw information from
these different kinds of resources and put it in working memory to tackle
problems.
Nehm has been testing this concept for evolution. In one experiment,
more than 200 participants solved problems in which just one feature was
manipulated at a time (Nehm and Ha, 2011). The experiment looked at
which surface features are problematic for learners, such as scale (such as
intraspecific or interspecific), polarity (such as trait gain versus trait loss),
taxon (such as plant or animal), and familiarity. The experiment measured
the accuracy of their scientific thinking.
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30 THINKING EVOLUTIONARILY
The results of this experiment show that students have more trouble
reasoning about the loss of traits than the gain of traits. They also have
greater difficulty reasoning about the loss of traits between species than
within species. But in reasoning about the gain of traits, there is no dif-
ference between the interspecific and intraspecific situations. Similarly,
students have more misconceptions about the loss and gain of traits
between species than within species. The hardest problem for students
to solve, said Nehm, is the loss of traits between species. “If students can
handle that, that’s the highest level of competency. But do we ask those
questions? No.”
Also, students use more key concepts in solving problems involving
familiar animals than unfamiliar animals, but this trend is not seen for
plants, all of which seem to strike students as unfamiliar.
These surface features have a remarkably powerful influence, said
Nehm. “If you want to show your class is doing great, I can design an
assessment for you. If you want to show your students are failing, I can
design an assessment for you. All I have to do is manipulate surface fea -
tures because students’ reasoning is so tied to these features. And yet we
pay no attention to this in any textbook or in any assessment.”
The bottom line is that “surface features matter, and we need to be
more precise in our instructional strategies to deal with these.” Because
misconceptions are surface-feature specific, instructional examples must
be carefully chosen. Furthermore, assessments of competency must
include authentic production tasks, such as explaining how evolutionary
change occurs, not just fragmented knowledge selection tasks.
EVOLUTION ACROSS THE CURRICULUM
In 2007, Nehm reported on an introductory biology course that was
changed so that every topic included evolution, while a parallel course
was taught using a traditional curriculum (Nehm and Reilly, 2007). The
outcomes were not substantially different. “It’s an awful downer at this
conference,” he admitted.
However, one single study is not enough to draw broad conclusions.
For one thing, students have difficulty learning evolution, so teaching it
in the same way is probably not going to lead to progress. “If you have a
problem with A and you give lots more A, the chances are it’s not going
to lead to a substantial improvement.”
Also, as students work through the biology curriculum, they move
from naïve models to mixed models to scientific models, but progress is
very slow—25 percent of students who have completed a course on evolu-
tion and additional coursework still used mixed models.
Determining the conditions under which students can effectively
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LEARNING ABOUT EVOLUTION: THE EVIDENCE BASE
learn about evolution will require truly randomized controlled trials,
Nehm concluded. Developing such trials will be difficult, he acknowl-
edged. “But my perspective—which, again, is only my personal perspec -
tive and may be wrong—is that if people can do it in medicine, where
people are dying, we should be able to do it in education.”
REFERENCES
Baldwin, B. C., Ha, M., and Nehm, R. H. 2012. The Impact of a Science Teacher Professional
Development Program on Evolution Knowledge, Misconceptions, and Acceptance.
Proceedings of the National Association for Research in Science Teaching (NARST) Annual
Conference, Indianapolis, IN, March 25-March 28.
National Research Council. 2000. How People Learn: Brain, Mind, Experience, and School: Ex-
panded Edition.Washington, DC: National Academy Press.
National Research Council. 2001. Knowing What Students Know: The Science and Design of
Educational Assessment. Washington, DC: National Academy Press.
Nehm, R. H. 2006. Faith-based evolution education? Bioscience 56(8):638-639.
Nehm, R. H. 2007. Teaching evolution and the nature of science. Focus on Microbiology Educa-
tion 13(3):5-9.
Nehm, R. H., and Ha, M. 2011. Item feature effects in evolution assessment. Journal of Re-
search in Science Teaching 48(3):237-256.
Nehm, R. H., and Reilly, L. 2007. Biology majors’ knowledge and misconceptions of natural
selection. Bioscience 57(3):263-272.
Nehm, R. H., and Ridgway, J. 2011. What do experts and novices “see” in evolutionary
problems? Evolution: Education and Outreach 4:666-679.
Nehm, R. H., and Schonfeld, I. 2007. Does increasing biology teacher knowledge about
evolution and the nature of science lead to greater advocacy for teaching evolution in
schools? Journal of Science Teacher Education 18(5):699-723.
Nehm, R. H., and Schonfeld, I. 2008. Measuring knowledge of natural selection: a Aompari -
son of the CINS, and open-response instrument, and oral interview. Journal of Research
in Science Teaching 45(10):1131-1160.
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