Nature of Science
The concepts and topics related to an understanding of the Nature of Science were thoroughly taught. Using repeated references to the history of evolutionary thought, the evolutionary literature, the scientists and research programs that produced this literature, and the ongoing debates between those scientists, the course provided a very real, robust picture of how science proceeds. As Duschl suggests (1990), this epistemological approach to scientific knowledge enhances students' understandings of the scientific concepts as it provides a portrait of the development of science as a human endeavor.
The course instructor also stressed the nature of science through his deductive approach to teaching scientific concepts. This deductive approach took the form of defining the concept, then describing a biological situation (a description taken from the research literature), and having students analyze the situation based upon the concepts presented in the course. Finally, the instructor would explain how the concept explained the data and where it fell short. This technique has two benefits; it provides a very real context for a concept, and it demonstrates how concepts are closely tied to evidence.
The living environment
Specific concepts from the sections Diversity of Life and Heredity were addressed as they directly related to evolution. The instructor assumed a level of biological literacy on the part of students in the class and the teaching of these concepts (classification, sorting of genetic information, mutations) was structured upon that knowledge.
Within the section Evolution of Life, many of the topics and concepts were addressed in a very thorough, integrated fashion. Concepts of the mechanisms of evolutionary change, including natural selection, received a great deal of instructional time and energy. As mentioned in the previous section, the instructor's deductive approach to teaching coupled with a reliance on biological data helped illuminate concepts and their meaning in natural situations. This approach could be strengthened, however, by allowing students even more time to consider data. A biological situation could be presented, then the students broken into small groups to discuss the data, and present their findings. Alternatively, the biological situation could be described before the end of class, and students could be required to bring an explanation to the next session. However, these are simply possible ways to improve what we believe is already an appropriate pedagogical approach to such detailed, complex information.
One topic related to the section, Evolution of Life, did not receive the focused attention of other topics. As detailed by the instructor, the course was designed to allow students to understand major evolutionary concepts and to see the articulations among these concepts. Emphasis was not placed on the fossil and molecular evidence for evolutionary change. The processes through which change occurs and the patterns of change received the bulk of attention. Although one lab focused on anatomical evidence of human phylogeny and a second concentrated on the molecular evidence used to construct phylogeny, the emphasis was not on evidence used to support the historical reality of evolution.
The human organism
Within the section on Human Identity, the topic of evolution from simpler organisms was addressed through attention to the patterns of evolutionary change in primates. This topic was the focus of one laboratory exercise and the final day of lecture. While this topic was treated with the same attention to detail and evidence used to present other topics, human evolution is an emotional issue for many students (Demastes, Good, Peebles, in press). As such, the placement of this topic at the end of the course has both pedagogical advantages and flaws. Treatment at the end of the semester allows students to apply all the principles they have learned to understand human evolution. Alternatively, this placement limits the amount of time and consideration students could devote to the topic and may reinforce the anthropocentric conceptions of humans as the pinnacle of evolution (Demastes et al., 1992).
Historical Perspectives
As described by Duveen & Solomon (1994) and Duschl (1990), an understanding of the nature of science can be closely tied to an analysis of the historical development of scientific knowledge. The instructor's careful analysis of the historical development of evolutionary theory served to not only provide students with an important component of cultural knowledge, it taught important concepts by countering prominent alternative conceptions, and provided students with a deep and contextual understanding of how science proceeds. Within the section, Explaining the diversity of life, the topics of (a) acquired features versus natural selection, (b) evolutionary theory and resistance, and (c) the genetic basis of evolutionary theory were represented in great detail and formed the focal point of the early weeks of class instruction.
Is attention called to appropriate connections among concepts presented in the course? in other courses?
As described by Trowbridge & Wandersee (1994, p. 459), evolution is a "concept rich" theoretical framework. The concepts in this framework build upon and relate to one another. A review of the multiple literacy topics addressed in this course underscores this complexity, a situation that is recognized by the course instructor. Early in teaching the course, the instructor participated in a research project in which students constructed concept maps of lecture material (see Related Research at the end of the course description). By comparing the maps constructed by different students, critical junctures of the course were identified. Critical junctures are defined as conceptual watersheds, or peak times of difficulty in understanding course content. Through the identification of such difficult periods, the instructor redesigned lectures to make these topics more clear. Additionally, students' concept maps demonstrated the difficulties students have identifying linkages among evolutionary concepts. Based on this information, the instructor has made these conceptual linkages very clear in his teaching.
As mentioned previously, much of the course instruction built upon prior biological knowledge of the students. For instances in which students' knowledge had to be very sophisticated in order for subsequent concepts to be understood, such as variation produced through assortment of genes in sexual reproduction and result of mutation, the instructor thoroughly reviewed the basic concept and stressed linkages of these ideas to other concepts. Other concepts and skills, such as the geological time scale and mathematics, were simply assumed and linkages were not defined.
Does the course attempt to address student misconceptions that have been summarized in Benchmarks Chapter 15: The Research Base?
Prominent alternative conceptions directly addressed through this course and its associated laboratory exercises include:
a) the blending of the production of variation in a population with the survival of that trait in a population,
b) need, environmental conditions, use/disuse producing new variation,
c) evolution involving a gradual change in an entire population instead of the percentage of a population with a particular trait, and
d) the teleological process of adaptation.
Many of these strongly held alternative conceptions were addressed through attention to the historical development of evolutionary theory (as proposed by Jensen & Finely, 1993), others were addressed through laboratory activities (such as the bead-bug activity described by Bishop & Anderson, 1985), and others were addressed through an explanation of the scientific conception compared to the alternative explanation.
The first two pedagogical practices, the historical development and laboratory activities, have been shown to be reasonably effective in reasearch studies (Jensen & Finley, 1993; Zuzovsky, 1994; Bishop & Anderson, 1990). The third option, a rationalistic analysis of the scientific conception, is the traditional approach, which has been shown to be less effective is displacing strongly held alternative conceptions (Bishop & Anderson, 1990; Demastes et al., 1992; Demastes, Good, & Settlage, 1995). The effectiveness of the latter approach could be enhanced by allowing students to work through problems requiring explanations and comparing their results. This allows students to recognize both the inadequacies of their own explanations and the strength of the scientific conception, as suggested by Posner, Strike, Hewson, & Gertzog (1982). Although the beginnings of such activities already occur in the class, students are not required to take ownership of their ideas. Restructuring how phenomena are analyzed and how students communicate their ideas would be helpful. However, such activities would require a radical increase in class time.
Is the course structured to make possible the collection of students' understandings of the concepts targeted? Are the data used to revise the course?
Early versions of the course incorporated student production of concept maps based on the lecture material and quizzes based on the readings. Although the intent of both teaching practices was to improve student understanding of the material, these practices also produced important insights into students' thinking. These insights were used to refine the course through adjustments in lecture presentation, incorporation of more examples, and omission of material. It is the instructor's belief that the concept maps produced by the students were of more value to him, in his revision of the course, than they were to the students.
Incidentally, both teaching practices (concept maps and quizzes) have been abandoned in subsequent versions of the course. Although many students recognized the strengths of concept mapping, they resented the time this alien study technique required.
Are students engaged in activities that give them first-hand experiences with concepts and then provide opportunities to reflect on their activities?
As mentioned in the preface to the laboratory manual, evolutionary concepts traditionally were thought to be too abstract for laboratory activities, and many early courses omitted any demonstrations or student application of concepts. However, the course instructor believes that many evolutionary concepts, because they are abstract, often are not grasped by students in a lecture-only course. For this reason, the most important and fundamental concepts should be addressed in a more inquiry-based, student-centered fashion. As described in the laboratory preface:
Although these laboratories are deceptively simple in design, it must be remembered that they focus on complex, abstract concepts that beginning students of evolution usually fail to grasp. Hence, the apparent simplicity of the laboratories is intentional, as is the avoidance of sophisticated experiments and computer simulations that tend to mystify, rather than clarify. (Hafner, 1994, p. 1)
The focus of some of the laboratories and the accompanying exercises include:
a) Biodiversity addressed through a tour of museum collections and an exercise in rapid assessment of biological diversity of four simulated communities.
b) Taxonomy and classification addressed through student generation of classifications of local organisms and a justification for these classifications.
c) Biometry addressed through student measurement of variation in a natural population and methods of summarizing descriptive statistics.
d) Population genetics addressed through analysis of sample electrophoretic data.
e) Genetic drift addressed through a simulation of genetic drift using a population of beans.
f) Natural selection addressed through a simulation predator-prey selection. (This is similar to the exercise described by Bishop & Anderson, 1985).
g) Historical biogeography addressed through a simulation of mammalian colonization of various simulated habitats.
h) Phylogeny reconstruction addressed through student construction of four trees to represent the relationships among four simulated organisms.
Are opportunities provided for students to apply their knowledge in varied context--e.g., explaining everyday problems, considering alternative solutions to practical problems?
As discussed previously, many opportunities were provided for students to apply their knowledge, both in and out of lecture. But the nature of the application required in lecture was relatively superficial, so that students might simply listen to the explanation eventually offered by the instructor. In the laboratory, the application required of the students was far more in-depth, and completion of lab reports required students to apply concepts and take ownership of their decisions, an ideal situation for eliciting conceptual change.
The nature of the situations to which concepts were applied differs
from that described by SFAA. The evolution course and lectures dealt
with situations that would be of interest and concern to biologists;
outside of the realm of biology, such situations could not be considered
"everyday." Although such distinctions are to be expected in a college
level evolution class, the incorporation of more human/technology-centered
examples (e.g., evolution of resistance in microbes and actions of antibiotics,
pesticides and resistance, human variation) may help students with the
application of these concepts to understand their lives.
REFERENCES
Bishop, B. A., & Anderson, C. W. (1985). Evolution by natural selection: A teaching module (Occasional Paper, No. 91). East Lansing, MI: Institute for Research on Teaching, Michigan State University.
Bishop, B. A., & Anderson, C. W. (1990). Students' conceptions of natural selection and its role in evolution. Journal of Research in Science Teaching, 27, 415-427.
Demastes, S. S., Good, R. G., Sundberg, M., & Dini, M. (1992, March). Students' conceptions of natural selection: A replication study and more. A paper presented at the meeting of the National Association of Research in Science Teaching, Boston, MA.
Demastes, S. S., Settlage, J., & Good, R. (1995). Students' conceptions of natural selection and its role in evolution: Cases of replication and comparison. Journal of Research in Science Teaching, 32, 535-550.
Demastes, S., S., Good, R., & Peebles, P. (in press). Students' conceptual ecologies and the process of conceptual change in evolution. Science Education.
Duschl, R. A. (1990). Restructuring science education: The importance of theories and their development. New York: Teachers College.
Duveen, J., & Solomon, J. (1994). The great evolution trial: Use of role-play in the classroom. Journal of Research in Science Teaching, 31, 575-582.
Hafner, M.S. (1994). Evolution laboratory: Laboratory exercises and discussions in evolutionary biology. Baton Rouge, LA: Louisiana State University.
Jensen, M. S., Finley, F. N. (1993, April). Teaching evolution using historical arguments in a conceptual change strategy. A paper presented at the meeting of the National Association of Research in Science Teaching, Atlanta, GA.
Posner, G., Strike, K., Hewson, P., & Gertzog, W. (1982). Accomodation of a scientific conception: Toward a theory of conceptual change. Science Education, 66, 211-227.
Trowbridge, J. E., & Wandersee, J. H. (1994). Identifying critical junctures in learning in a college course on evolution. Journal of Research in Science Teaching, 31, 459-473.
Zuzovsky, R. (1994). Conceptualizing a teaching experience on the development of the idea of evolution: An epistemological approach to the education of science teachers. Journal of Research in Science Teaching, 31, 557-574.