Explanation For Course Design

The existing literature on students' and teachers' conceptions of the nature of science played a critical role in course design and continues to strongly influence revisions in course activities. The literature has influenced both the topics included in the course as well as the instructional approaches and activities used to communicate critical ideas about the nature of science.

How were course topics determined?

Although the "nature of science" has been defined in a variety of ways, it most commonly refers to the values and assumptions inherent to science, scientific knowledge, and/or the development of scientific knowledge. Clearly, the "nature of science" is a complex area of study which can be carefully analyzed for many years without achieving expertise. Given the obvious time constraints imposed by a single course, the selection of topics and activities for a course designed for inservice teachers needed to carefully consider those aspects of the nature of science most critical for the classroom teacher.

Although the time allocated for inservice instruction is realistically not under control of the instructor, the specific topics addressed is under his/her direct control. Topics included within the development of the course were those considered to be foundational to a teacher's understanding of the nature of science. Furthermore, the areas focussed on were those considered (based on prior research and experience) to be the most problematic (but accessible) for secondary level students. The research reports that were particularly influential in the selection of course topics and design were:

Aikenhead, G. (1987). High-school graduates' beliefs about science-technology-society. II. Science Education, 71(4), 459-487.

Duschl, R.A., & Wright, E. (1989). A case study of high school teachers' decision making models for planning and teaching science. Journal of Research in Science Teaching, 26(6) 467-501.

Lederman, N.G. (1992). Students' and teachers' conceptions of the nature of science: A review of the research. Journal of Research in Science Teaching, 29(4), 331-359.

Lederman, N.G., & O'Malley, M. (1990). Students' perceptions of tentativeness in science: Development, use, and sources of change. Science Education, 74(2), 225-239.

Rubba, P.A., Horner, J., & Smith, J.M. (1981). A study of two misconceptions about the nature of science among junior high school students. School Science and Mathematics, 81, 221-226.

Zeidler, D.L., & Lederman, N.G. (1989). The effect of teachers' language on students' conceptions of the nature of science. Journal of Research in Science Teaching,

26(9), 771-783.

Following extensive deliberation based upon prior research on students' and teachers' conceptions of the nature of science, the following aspects of the nature of science were those selected for in-depth attention: 1) tentativeness, 2) observation versus inference, 3) nature and function of scientific theory, 4) nature and function of scientific law, 5) subjectivity and creativity in science, 6) empirical basis of scientific knowledge, 6) social and cultural influence on science.

Although each of the six identified aspects of the nature of science are problematic, the nature and function of scientific theories and laws are, perhaps, the most difficult to communicate to students. In particular, even though students are quick to accept the idea that scientific knowledge is tentative, they still view theories and laws as having a hierarchical relationship with laws being viewed as proven laws. Indeed, students with professed tentative views often view laws as absolute. There is little doubt that this misconception is continually fostered (perhaps more so than THE scientific method) by textbook presentation of the categories of scientific knowledge (e.g., hypotheses, theories, laws, principles, etc.). Furthermore, although students are familiar with examples of theories changing, they are not very familiar with changes that occur within scientific laws. Perhaps because changes in theories are more dramatic and, therefore, more pedagogically impressive instructors often use theories as examples of tentativeness in science as opposed to theories. Consequently, more time and activities are devoted to the nature and function of scientific laws and theories. It is a topic that is continually revisited throughout the course.

The difference between theories and laws in science is primarily one of the difference between inference and observation. Consequently, continual attention is given to what patterns have been observed and what patterns have been inferred in various activities. Students are periodically involved in activities in which theoretical models are developed from limited data sets. These activities seem to be the most effective at communicating the difference between theory and law. Addressing the lack of a hierarchical relationship between the two is fairly simple once students grasp the concepts. It would not make much sense for an inferred explanation for observable phenomena (scientific theory) to develop into something that is an simply an identified relationship among observable phenomena (scientific law). Theories do not turn into laws or vice versa.

The natural association among the various topics addressed in the course facilitated consistent attention to establishing connections among course topics. Furthermore, there was a concerted effort to use examples from students' prior learning in science courses to illustrate sources of misunderstandings as well as for support of the assertions being made regarding scientific knowledge. These connections to prior learning experiences helped make the course content more concrete as well as establish the importance of pedagogical approach to subsequent student understandings of the nature of science.

The course's success at helping to dispel students' misconceptions about the nature of science is partially the result of the cohesiveness of "messages" presented throughout the course. That is, there is a continual spiraling back to concepts previously discussed in recognition of how difficult they are for students to grasp. For example, the relationship pf scientific theories and laws is only clarified through periodic activities that involve students in either the development of models from limited data or through readings of historical accounts of the developments of various scientific theories and laws.

However, it is also important to note that there is a cohesiveness throughout the total course of study at Oregon State University. There are several themes that extend throughout all of the science education courses (preservice and inservice). One of the themes is "nature of science." In particular, students are continually asked to assess how various instructional materials, activities, or instructional segments are related to the nature of science. They are asked to determine if there is a consistency, how consistency might be created if it is lacking, and whether nature of science is a necessary consideration for a particular instructional event. It is through this constant reflection that our students not only adopt an accurate conception of the nature of science, but they also develop an important habit of consistently thinking about the nature of science whenever they consider planning and implementation of instruction.

All students in our preservice and inservice programs are expected to take a course in the history of science. A popular course, taken by most students, focuses on the history of evolutionary. Thus, my course is provided with a common reference point of a particular scientific theory about which most students (regardless of science specialty) have read extensively. In addition, all students in our programs must possess at least a B.S. degree in a science area. The laboratory activities they have experienced are consistently used as reference points to support ideas related to the nature of science or the teaching of the nature of science. For example, Punnet squares and the hardy Weinberg Principle are commonly covered in introductory genetics courses through a combination of laboratory experiences and tedious calculations. Students typically do not gain an understanding of the Punnet Square as a probability matrix or the reason why one would want to calculate gene frequencies with the Hardy Weinberg formula. In short, they do not know the relationship between the theoretical predictions of these tools and actual occurrences. Constant references to examples such as these help students to understand the roles of assumptions, predictions, and empirical tests in science. They also allow students to reflect upon how science might be taught in a a more meaningful manner.

Does the instructional approach used in the course engage students in activities that provide "hands-on" experiences with concepts and opportunities for reflection?

The general instructional approach used in the course is an integrated combination of readings, discussions, demonstrations, and "hands-on" activities. Students are repeatedly expected to complete various reading assignments and be prepared to discuss these during the next class meeting. Demonstrations and "hands-on" activities are used to further clarify issues raised in discussions and to surface additional concerns and questions. This cycle of activities provides students with varied exposures to the concepts and continuous opportunities to reflect upon their own learning. Furthermore, there is a continued effort to have students reflect upon the usefulness and grade level appropriateness of all activities relative to actual classroom application.

The reflective aspect of student activities is a critical aspect of course design. Simply having students participate in science demonstrations or independent laboratory activities/investigations has not been an effective approach for promoting students' understanding of the nature of science. In such situations, students primarily focus on the science content inherent in the activity and there is little cognizance of the intellectual and epistemological activity being performed. Students fail to be influenced by "nature of science" oriented activities if the nature of science is not made explicit. Students do not understand that the interpretation of scientific data and the development of questions for scientific investigations are steeped in a particular paradigm or theoretical perspective. They will develop questions and interpret data without understanding this key point, unless it is made explicit. Consequently, after each activity in the course students are asked to "step back" and reflect on the intellectual activity as opposed to the results. For example, following a demonstration of Heron's Siphon (a pair of two sealed cans, connected by a hose and pair of glass tubes between which a flow of liquid is mysteriously initiated), students are asked to reflect on how they determined the contents of the cans, how they tested their ideas, why certain explanations were considered correct while others not, and whether a single correct answer could be achieved. In short, the explicitly addressed focus of discussion is ultimately on the how the students approached the problem as opposed to the final solution. The focus is on the nature of science as opposed to the science content.

Do students have an opportunity to apply their knowledge in varied contexts?

The "final" phase of any instructional sequence is to assess whether students have actually learned what was intended. The most effective approach is to have students apply their knowledge to new and varied situations. Periodically, students are expected to apply their knowledge of the nature of science to actual science. In particular, when course participants have arrived (by their own construction) to a particular perspective, they are asked to test/apply their understanding to actual case studies in science. One particularly effective application pertains to students' "revelation" that the interpretation of data is constrained by the currently dominant paradigm in a particular area of study. Students are then asked to read an article by Stephen Brush titled, "Inside the Earth." This article recapitulates the history of research on the determination of the contents of the interior of the earth. Students are asked to apply their newly arrived at conceptions of science to "actual science" to see if there is any consistency. In a way, students are scientifically testing their conceptions of the nature of science.

In addition to applying their knowledge of the nature of science to varied contexts, students are also expected to apply their knowledge of how to teach the nature of science. As mentioned, all students are required to develop instructional materials that will hopefully be used with their own students. A selected sample of the materials must be demonstrated to other class participants. Class participants are required to respond with constructive suggestions to these presentations. Consequently, it is clear that students are provided with opportunities to apply the knowledge they have gained and receive the benefit of their classmates' varied experiences and backgrounds.

How is the course evaluated formatively and summatively?

From the very inception of the course, periodic data have been collected on students extending throughout the duration of each course offering. That is, students are asked to complete an open-ended questionnaire on various aspects of the nature of science during the first class meeting. This questionnaire has been used in previously published research (Lederman & O'Malley, 1990) and it targets many of the misconceptions cited in literature on teachers' and students' understandings' of the nature of science. The same questionnaire is administered upon completion of the course and, during certain years, has been routinely followed by a videotaped interview. The data generated through these questionnaires (i.e., beginning of course administration) have been used to design class activities and for summative evaluation of the course (i.e., administration of questionnaire and interview following course). In particular, data collected on students' understanding of tentativeness in science clearly indicated that students viewed theories as tentative, but laws as absolute. Furthermore, it was clear that they believed theories eventually developed into laws. Finally, creativity in science was relegated to the design of experiments, while given no role in the interpretation of data. These results lead to the development of numerous course activities that required students to collect data, develop inferences or hypotheses from observations, and then test these hypotheses. These activities provided effective frames of reference for discussion of the aforementioned areas of confusion.

Systematic evaluation of students' completion of writing assignments (i.e., reaction papers) and class projects provide a more comprehensive assessment of course success. Of particular note are the instructional materials created by course participants. These materials have consistently exhibited applied knowledge of the subject matter included within the course. This applied knowledge is of the most value to the instructor since the primary objective of the course is to enable teachers to facilitate the development of accurate understandings of the nature of science in their students.

Students are encouraged, but not required, to use the materials they create during the following year. It is important to note, however, that all students must demonstrate a selected sample of their materials to the rest of the class. Approximately 20% of the course participants have reported using the materials created and have consistently reported (using various approaches to data collection) success in improving their students' conceptions of the nature of science. Using a feedback loop to provide further evidence for the quality of instructional materials, the author uses selected materials during subsequent offerings of the course, activities with preservice teachers, and/or with actual secondary students. Again, the positive impacts have been quite encouraging.