Download Pre-assessment Report - Penn Arts and Sciences

Amy Dewees
EDUC 536-631
December 3, 2005
Pre-assessment Project: Evolution
Part I: Background Information
a. Introduction to Evolution:
Evolution is defined as the change of living organisms over long periods of time. It
explain how life has changed and developed from the first organisms to all the diverse species
that currently exist today. Many scientists believe that it is “the most single unifying theme
within the discipline of biology as it encompasses topics such as genetics, reproduction, animal
behavior, and ecology (4)”, as a result of this, it is imperative that students fully understand the
process of evolution.
The most commonly accepted theory of evolution was proposed by Charles Darwin in
1859, but he was not the first biologist to propose a theory for evolution. There were many
naturalists that suggested that life evolved over time as did the earth, but only one such scientist
proposed a comprehensive model for the evolution of life on earth. This was proposed by Jean
Baptiste Lamarck in 1809. The mechanism Larmark proposed to explain how life evolves and
becomes adapted to an environment consists of two principles. The first is the principle of use
and disuse. Lamarck proposed that an organ or other structure that is used frequently will
become stronger and larger, those that are not used as frequently will atrophy and eventually
disappear. His second principle was the principle of the inheritance of acquired traits. Lamark
proposed that changes that occur to an organism during it’s lifetime will be passed on its’
offspring. Lamarck used his two principles to explain the evolution of giraffes. He suggested that
the giraffe stretched its neck in an attempt to reach leaves that were higher up on the trees. Since
the giraffes stretched their necks so frequently they became longer and the offspring of these
giraffes with stretched necks also had stretched necks and over generations of stretching their
necks reached their current length. In essence he suggested that the behavior of the giraffes
changed their DNA which is what transmitted the longer necks to the offspring. Although
Lamarck’s theory is very flawed, his ideas were revolutionary in a time when creationism was
the accepted explanation for life on earth.
The modern theory of evolution was proposed by Charles Darwin. In 1831, at the age of
22, Darwin traveled the world aboard the Beagle as the ships’ naturalist. While on the journey he
collected specimens from many different locations including the jungles of Brazil, the grasslands
of Argentina, the Andes mountains, Tierra del Fuego near Antarctica, and the Galapagos Islands
where he encountered species found nowhere else in the world. During his time on the Beagle,
Darwin also read many books including a work be Charles Lyle. A contemporary of Darwin,
Lyle proposed that the earth was very old and had changed over time. Darwin also read an essay
by Thomas Malthus, an economist, who proposed that the human population was growing too
rapidly and would eventually run out of food.
Following his journey, Darwin spent the next twenty years examining his specimens and
adding to his collection. He observed farmers and how they generated new varieties by breeding
individuals with desired characteristics. Based on his observations and the reading of Lyle and
Malthus, Darwin published his book, The Origin of Species in 1859.
In his book, Darwin explained how populations of individuals become better adapted to
their environment. He called the mechanism for this change, natural selection, and was based on
four statements:
“1. Individuals of any population vary from one another in many characteristics. Even
siblings differ.
2. These variations can be inherited.
3. Members of a population produce more offspring than the environment can support.
4. Those individuals whose inherited characteristics fit them best to their environment are
likely to leave more offspring than less fit individuals. (Campbell, 424)”
Natural selection occurs because of an interaction between a population and its’
environment. We now know that variations in a population exist because of changes in DNA,
which produce new genes. Some of these changes result in traits that may give individuals
possessing those traits an advantage over those individuals without the trait, allowing them to
produce more offspring. Over many generations the frequency of the desirable genes increases in
the population and as a whole the population changes.
Evolution and Natural Selection are known as theories. According to biologists, a theory
is “an explanation of a set of related observations or events based upon proven hypotheses and
verified multiple times (Wilson).” Theories are often compared to scientific laws which are
statements that explain an action and are accepted as true. A theory is not any less supported or
accepted by scientists, it is just more complex and is often used to explain related ideas or
phenomena.
b. National Science Education Standards for Biological Evolution:
•
Species evolve over time. Evolution is the consequence of the interactions of (1) the
potential for a species to increase its numbers, (2) the genetic variability of offspring due
to mutation and recombination of genes, (3) a finite supply of the resources required for
life, and (4) the ensuing selection by the environment of those offspring better able to
survive and leave offspring.
c. Research on student’s thinking on evolution:
There have been many student misconceptions identified in regards to evolution. These
include the idea that evolution is a “theory”, the origin of the traits organisms possess, and the
processes involved in natural selection. There have been many other misconceptions identified
and in addition to any confusion about the processes involved many students have been found to
have problems accepting the theory of evolution because of religious beliefs.
Some students have been found to believe that because evolution is referred to as a
theory, it is a “best guess” and is not supported by scientific fact or evidence (5). In reality a
theory means a “a set of hypotheses that have been tested repeatedly, have not been rejected, and
explain current data and predict future observations (5).”
There seems to be a great deal of confusion about the process of evolution. Evolution is
the result of two processes: the variation that naturally occurs within a population as the result of
mutations or genetic recombination and the influence or selection of traits by environmental
factors. Many students seem to believe that organisms change as the result of a desire to do so or
the desire to survive. Other students have been found to believe that only the environment causes
traits to change over time. Students also never seem to understand that the variations that are
present in a population are naturally occurring and are always present, students think that the
traits arise because of the environment (4).
Part II: Analysis of pre-assessment results
a. Pre-assessment Administration Procedure:
The pre-assessment questions were given to three Biology classes consisting of 9th and
10th grade students. The first class consisted of 9 students, 4 boys and 5 girls, four 9th grade
students and five 10th grade students. This is a very diverse class: two students receive additional
support but are not labeled as special education, another student receives language support
because English is her second language, and two students are identified as gifted. The second
class consisted of eight students; four girls and four boys, four are in 9th grade and four are in
10th. Of these students one receives emotional and academic support and another is in learning
support. The third class the questions were administered to consisted of 24 students; 14 girls and
10 boys. Of these students two receive learning support, two receive additional academic
support, and four are gifted. On the day the pre-assessment was given some students were on a
field trip so all the students did not participate. The student for whom English is a second
language had a very difficult time as did most of the learning support students.
About 20-25 minutes of the class period was dedicated to taking the pre-assessment. The
students were told during the previous class period that they would be answering some preassessment questions. They were not told the topic, just that it was being used for a project and
was not going to impact their grade. They were given one question at a time and were told to
write as much as they could to answer the question. I read the questions aloud and told them to
read it with me. I reminded them that they could refer to things they learned in biology, in other
classes, to TV shows they had seen, or to their own personal opinions. They only needed to
explain their position with as much detail as they could so that someone would completely
understand their point of view. The class did not move on to the second question until everyone
had finished the first, this took about 10 minutes. The second question was administered the
same way as the first and also took about 10 minutes. The students were given participation
points if they showed some effort in answering the questions. I did circulate through the room to
see that everyone was writing something and not leaving the paper blank. The students
frequently expressed concern and anxiety because they did not know the “right” answers, when
they expressed their concerns I told them this was just so I could have an idea of what they knew
or what they thought. I told them to just do their best and not worry about the accuracy of their
answers.
b. Rational for questions:
My reason for choosing evolution as the topic for this pre-assessment project is that I
have found this to be a very difficult topic to teach, partially because students have many
preconceived ideas about evolution. There are many reasons for these misconceptions, one is that
students don’t really understand the processes involved. They seem to think they already know
the answers so they dismiss information discussed in class. Another obstacle is the fact that
evolution is called a theory and this seems to make the students think there is not evidence to
support it. I have often heard, “Why do we have to learn this, it’s only a theory, so what’s the
point.” Lastly, some students have strong religious beliefs that prevent them from accepting the
idea of evolution.
The first question addressed misconceptions students may have about the processes
involved in evolution. This question provided information about the evolutionary theories of
Lamarck and Darwin. The students were given two scenarios involving the evolution of giraffes,
an example that is often used to demonstrate the differences between the two evolutionary
theories. The first scenario, A, described the evolution of current long-necked giraffes in terms of
Lamarck’s theory and the second scenario, B, described it based on Darwin’s theory. The
students were not given the names of the scientists, just A and B and were asked to choose which
one they thought was correct and why. This showed their preconceptions about how evolution
occures.
The second question addressed the misconceptions associated with the difference
between a theory and a law. The students were asked to explain the difference between the two
and if evolution would become a law. This illustrated what their understanding of the two terms
was, and also gave me some idea of how they thought both came to be accepted.
c. Analysis of student’s responses:
Table 1: Student Responses to Question 1
Choice A (Lamarck’s
Theory)
Choice
12
Students in groups
9
who though species
had a “desire” to
change
Choice B (Darwin’s
Theory)
19
5
Undecided/Both A
and B
1
1
The first pre-assessment question asked students which theory of evolution they agreed
with most, Darwin’s theory or Lamark’s. 32% of the students agreed with the Lamarck’s theory
of evolution, 59% of the students agreed with Darwin’s theory, and only one student was
undecided and created her own version of evolutionary theory. One theme that was common
amongst the answers from all three types of responses was that organisms change or evolve
because they want to or as the result of their need to change. Some students even thought
organisms could change their DNA at will. One student thought the giraffes stretched their necks
to get to their food because they needed to adapt and the traits came about because they needed
to change. Another student thought that giraffes could use excess bones to form a longer neck.
One student out of the 32 students who answered the questions mentioned Darwin and
made the connection that the stronger more fit animals lived longer and produced more
offspring, a term that scientists call “fitness”.
Table 2: Student Responses to Part A of Question 2:
Theory
Law
Not proven
32
Proven many times/
Fact
32
All students believed that a law is scientific fact and has been proven many times and a
theory is not proven, it is an educated guess, or an opinion without enough evidence to support it
to become a law. Common reasons for why students thought a theory was not proven were that it
is a scientist’s opinion or an educated guess, it is an idea that needs improvement, it is something
that is open to interpretation, or that is it a new idea that has not been around long enough to be
accepted.
Table 3: Student Responses to Part B of Question 2:
Will Become a Law
Will Not Become a Law
15
6
Unsure/Maybe
4
There were fewer student responses to part B because a number of students did not
answer the second part of the question. Some ideas students had for when evolution could
become a law were that it needed to be around longer and that more people needed to accept it.
Common reasons for why it will not become a law were that we cannot go back in time and
therefore cannot observe evolution first hand, religion will not accept it, and many students
thought it can’t be proven by experimentation.
d. Analysis of findings:
The misconceptions of my students were consistent with those found in the research.
Although distinguishing between a law and a theory is not among the National Science Standards
for evolution it seems to be a stumbling block for many students. This is obvious from the fact
that all the students thought a theory was not as accepted as a law and many confused they term
theory with the term hypothesis. Many thought evolution was an educated guess that had not
been proven.
Many students were incorrect in their interpretation of the processes involved in
evolution. None of the students expressed the thought that variation exists naturally in a
population and only a few students mentioned DNA. Some students thought DNA could be
changed by the organism because of a desire to change. Confusion associated with the
occurrence of various traits and the mechanisms involving DNA could be related to the fact that
we have not studied genetics and DNA. Ordinarily these topics would be covered before
studying evolution.
The idea that organisms change to adapt in order to survive also shows a lack of
understanding of the mechanisms of evolution. According to the National Science Standards
Lamarck’s theories of evolution show a flawed line of thinking, he thought that
organisms have a desire to change. 50% of the students agreed with this idea. Lamarck’s theory
also involves the inheritance of acquired traits, many students believed that this was true as well.
e. Implications:
Knowing the ideas students have about a topic before teaching it can be very valuable
information. In order to help students overcome these preconceived notions, the teacher must be
able to identify them and then help the students to become uncomfortable with their beliefs and
question them. This has been found to be an effective way to overcome these obstacles.
Some possible ways to accomplish this may be for students to see a model of evolution
involving the use of camouflage to help a species to avoid a predator. This may cause some of
the students who claimed that evolution cannot be observed to reconsider their idea. Another
possible strategy may be to place students into small groups and assign them a variation in
humans or another species to research. In this they would need to find how the trait came about
and how the trait may be advantageous to a species survival. Some possible trait could be sickle
cell anemia in humans, antibacterial resistance in bacteria, and the beak shapes of Darwin’s
finches in the Galapagos Islands. Upon completing their research, each group could present their
findings to the class.
In order to help students understand the difference between a law and a theory a possible
method may be to have students research a specific law or theory, such as Newton’ laws of
motion, the big bang theory, the cell theory, or Boyle’s law. They could then present their
finding as either posters or power points and then as a class we could discuss the difference
between the laws and the theories. We could bring attention to the fact that many laws can be
represented with formulas and are statements that can explain an action whereas theories relate to
much more complicated phenomena.
Works Cited
Biggs, Alton, Albert Kaskel, Linda Lundgren, and Devi Mathieu. (1994) Biology Living
Systems. Westerville, Ohio: Glencoe Division Macmillan/McGraw-Hill.
Campbell, Neil A. (1987) Biology. Menlo Park, California: The Benjamin/Cummings Publishing
Company, Inc.
Dagher, Zaubeida R., Saouma Boujaoude. (April 7, 2005) Students’ Perceptions of the Nature of
Evolutionary Theory. Wiley IneterScience. Retrieved October 25, 2005.
Flammer, Larry. (1999) Human Evolution Unit.
www.indiana,edu/~ensiweb/lessons/unt.he.f.html. Retrieved October 26, 2005.
Mays, Allison. (January 31, 2001) Student Misconceptions of Evolution.
www.bamaed.ua.edu/~amays/misconceptionsummary.htm. Retrieved October 25, 2005.
Wescott, Daniel J. and Deborah L. Cunningham. (Spring/Summer 2005) Recognizing Student
Misconceptions about Science and Evolution. MountainRise
facctr.wcu.edu/mountainrise/archive/vol2no2/html/science_evolution.html. Retrieved October
25, 2005.
Wilson, Jerry. (2000) Scientific Laws, Hypotheses, and Theories. wilstar.com/theories.htm.
Retrieved November 27, 2005.