Influencing Teacher Understanding of the Nature of Science:
Data from a case of Curriculum Development
Lin, Tsai-Ku
Department of Physics, Kaohisung Normal University
Abstract:
The purpose of this study was to investigate the effects of the first-year field test of a paradigm-oriented history of scientific thought (POHST) curriculum on teachers’ understanding of the nature of science (NOS). The experimental group, which was exposed to the POHST curriculum, and the control group, which was taught using a traditional science curriculum, were administered a pretest and posttest using both the VOSTS and TVNOS instruments. Analyses of covariance and t tests showed that the understanding of physics teachers who experienced the POHST curriculum increased significantly in overall score and most of the subscales for both instruments; and the understanding of teachers who experienced the control-group science program decreased, but not significantly. Analysis of mean and frequency showed that 92% of the participants in experimental group make progress in overall scores and 67% of them reached a significant level (changed their view from traditional to contemporary). Additional qualitative data were collected in the form of open-ended surveys. The participants’ respond statements were coded according to the criteria of NOS, which are the consensus of science-educators’ community. The founding from the qualitative data agreed with the quantitative ones. Repeated the whole process in the second year with different participants obtained similar results. This suggested that the POHST curriculum, which emphasized the way of thinking not the knowledge of science, was effective for changing the teachers’ view of NOS.
Introduction
Understanding the nature of science is an important objective of science education designed to increase the scientific literacy of citizens. Since science teachers play a key role in science teaching, it is critical to develop teachers who have a contemporary view of the nature of science and its application to science teaching. Empirical evidence, however, shows that science teachers have inadequate conceptions of the nature of science (Lederman, 1992, 1998). Teacher misunderstandings have been attributed to science curricular materials and instructional practices which do not adequately reflect the nature of science.
Research Questions
Recent review also indicated that efforts to improve teachers’ conceptions of the NOS have achieved some success when either historical aspects of scientific knowledge or direct attention to the nature of science have been included. The purpose of this study was to determine the extent to which the paradigm-oriented history of science thought (POHST) course, an curriculum designed to facilitate the scientific literacy of teachers, impacted on teacher understanding of the NOS. The following null hypotheses were formulated and tested:
1. There will be no significant difference between teachers’ pretest and posttest scores, which measure an understanding of the nature of science for teachers who experience the POHST.
2. There will be no significant difference between teachers’ pretest and posttest scores, which measure an understanding of the NOS for teachers who experience an introductory history of science curriculum (HS).
3. There will be no significant difference between POHST and HS in regard to their understanding of the NOS.
These three hypotheses were tested using two different instruments, they are VOSTS (Aikenhead, 1992) and TVNOS (Lin, 1999).
Participants
The teachers included in this study were all senior physics and chemistry teachers who attended the same summer institute (teacher reeducation) program in Kaohsiung Normal University located in the southern part of Taiwan. In the first year, 114 science teachers participated in this study; 40 physics teachers constituted the experimental group 1, 37chemistry teachers served as the experimental group 2, and another 37 physics teachers served as the control group. In the second year, 85 science teachers participated in the study; 22 physics teachers in the experimental group 1, 23 chemistry teachers in experimental group 2, and 40 physics teachers in control group.
Teachers in the experimental group 1 experienced the POHST curriculum, experimental group 2 experienced an introductory history of science (HS) curriculum and the control group experienced a traditional science curriculum. The difference among POHST, HS and traditional science curriculum is shown in next section and Appendix I .
Paradigm-Oriented history of scientific thought
Many researchers have noted that the science curriculum has been and still is based on some out-of-date traditional views of the nature of science, which mainly originated from the Bacon-Galelian-Newtonian paradigm (BGN paradigm for short), and have been modified by the community of educators in science education and the philosophy of science. An historical anchor point for a delineation of this paradigm may be found in a few lines from the preamble to a draft written in 1703 by Newton of ‘a scheme for establishing the royal society’:
Natural philosophy consists in discovering the frame (structure) and operations (exertion of forces) of Nature, and reducing them, as far as may be, to general Rules of Laws,--establishing these rules by observation and experiments, and then deducing the causes and effects of things (ms cit. Westfall 1980, p632)
This scheme clearly indicates, explicitly or implicitly, the following generic aspect of the BGN paradigm:
1. The general goal of natural philosophy (natural sciences) is to discover the structure, the exertion of forces, and the general rules of Nature, which are already out there (an objective existence) (the position of realism and priorism).
2. The structure of the objective world is constructed by some invariant reality (corpuscles), and is a static existence inside the absolute space and time. (which is the axiom of the Newton paradigm) (the position of realism, positivism and absolutism).
3. The scientific method is used to deduce one thing from another (infer or draw as a logical conclusion, or derive by a process of reasoning), and the general rules or laws are established by (or induced from) observations and experiments (i.e., the solid foundation we can give to science itself must be based on observations, experiments or experience (the position of positivism and logical empiricism).
4. The general rules or laws are universally causal (not necessarily causal themselves, but only that they permit the deducing (in the sense of inferring) of causal relations). Chance, uncertainty, and probability play no role in these deterministic laws (the position of realism and mechanical determinism).
5. The general rules or ‘laws of Nature’ are true for all time (the position of realism).
The contribution of Francis Bacon was that he proposed the classical views of induction as the method of science first in 1602. This method was refined further by Robert Boyle in 1672, and Newton in 1687. The basic tenets of induction are that science inquiry consists of four stages : (1) observation and the collection of facts, (2) analysis and classification of those facts; (3) inductive derivation of generalizations from the facts, and (4) further testing of the generalizations.
The contribution of Galilean Galileo was that, besides experiments, he emphasized the importance of mathematics and logical (deductive) reasoning to find truth both in the natural world and in society. He believed that any science should yield knowledge, and that the only way to achieve this was by employing deductive reasoning based on indubitable premises, just like in Euclid’s geometry, or more particularly, in Archimedes’ statics. It was this conviction which underlay his famous remark that ‘the book of nature is written in the language of mathematics.’ The traditional view, at that time, was that natural philosophy (natural science) is essentially concerned with the investigation of causes, so mathematical reasoning, being abstract, is inappropriate for such an investigation. Galileo rectified this misconception; he thought of motion as a mathematical concept rather than an empirical or experimental one. The laws governing the motion of objects falling freely will be justified not on the basis of experiments with inclined planes, but by derivation from ‘true and indubitable’ axioms or general principles of motion. Because of the prominence given to mathematical methods, there is a natural tendency, which begins to be apparent in Galileo, to stress quantitative mathematical discourse.
At the turn of the 20th century, a new paradigm was gradually substituted for the BGN paradigm. This new paradigm started with Faraday and Maxwell’s concept of fields, which eventually led to Einstein’s relativity and revision of many improper BGN assumptions. Some examples are:
(1) The concept of fields unified the concept of corpuscles (matter) and force (cause). It became the fundamental constituent and dynamic of matter. This challenged the fundamental assumption of realism.
(2) The assumptions of absolute space, time, matter, and observation were artificial. This challenged the metaphysical assumption of absolutism.
(3) Relativity showed that the observer and the observed were part of a system and not separate entities; hence, the cherished ‘objectivity’ of the BGN paradigm had to be reevaluated, and much of the remaining edifice consequently crumbled. (E.g., can the scientist really be disinterested if he is a part of the reality that he is investigating and not apart from that reality? Are then theory-free observation and value-free investigation feasible?)
Another cornerstone of 20th century physics is quantum theory. The scientific background for the development of quantum theory, as for relativity, consists of Newtonian mechanics and Maxwell’s electrodynamics. From the epistemological point of view, the most significant inventions to the new quantum theory are Bohr’s principle of complementary, Heisenberg’s uncertainty principle, and Born’s probability interpretation of the material wave function. The Copenhagen interpretation of these inventions is a rejection of realism in favor of the view that one should not ascribe reality to entities that cannot be directly observed. In some cases, reality is even denied to entities that one does not happen to observe on a particular occasion, even though they could have been observed. In other words, reality is ascribed only to one’s own perception, not to the external world. This interpretation may become apparent from the following discussion:
(1) Bohr’s principle of Complementary says that: phenomena may have two apparently incompatible properties, such as wave and particle aspects. Neither by itself exhausts the nature of the phenomena. The experimental situation determines which aspect will be displayed.
(2) Heisenberg’s uncertainty principle suggests that physical variables, such as energy and time, momentum and the position of the wave-packet, can not be determined precisely, but there is a reciprocal relation such that the more accurately one quantity is determined, the less accurately the other one can be determined. Heisenberg consistently rejected what he called ‘materialism’---the belief in an “objectively real world whose smallest parts exist objectively in the same sense as stones or trees exist, independently of whether or not we observe them” (Heisenberg, 1958, p129) .
(3) Born’s interpretation is that the material wave function (or rather its absolute square) describes the probability distribution of a single particle or system of interacting particles. The statistical interpretation of the wave function does not mean that the particle has a well-defined position and momentum; and the wave function only represents our knowledge of it. Hence, rather than talk about the probability distribution of a particular property of the particle, one should really talk about the probability that a particular measurement will give a particular result. The property inferred from that result is not necessarily consistent with the property that would be inferred from the result of a different measurement of the same system. Therefore, the ideals of the traditional BGN paradigm, such as accuracy, completeness, invariance, unique, ultimate and determinism, have to be reevaluated.
Besides the continuing debate about the objectivity of Nature, there are questions about the experimental character of the scientific method. Recent philosophers of science have been critical of the traditional view that scientific inquiry is inductive, and that knowledge is obtained only from direct sensory experience. Criticisms of induction as the way in which science inquiry proceeds have been presented by Hempel (1966), who argued that the first three steps in classical induction proposed by the BGN paradigm (see p5) are untenable. The reasons are as follows:
(1) The first inductive step is that all facts should be collected without the use of a priori hypotheses lest the objectivity of science be threatened. Hempel showed that scientific investigation beginning this way could never proceed beyond the first step because the collection of facts would never end. Without hypotheses, there would be no basis for determining when sufficient facts for an inductive inference had been collected. More specifically, one could not determine if all facts related to the occurrence of an observed event had been collected or if more facts from future occurrences might be needed, even if only relevant facts were needed. There would be no standard for establishing what was relevant without admitting that a hypothesis or some other type of prior expectation had been guiding the observations.
(2) The second step in induction is the organization and classification of facts. Theoretically, there are an infinite number of ways in which a given set of facts can be organized and classified. To understand a particular phenomena, some organizations may be useful , but others may be nonsensical. Useful and meaningful organizations of facts can occur only in the context of a particular conceptual scheme. Each possible organization of facts presupposes the existence of certain conceptual knowledge. It is difficult to see how even the most rudimentary classifications could be made in a discipline unless various concepts had been assumed.
(3) The third and most important step in induction is to formulate new general principles from observed facts. Hempel indicated that a set of mechanically applicable (logical) rules of induction would be required for this process. The inductive rules would be, in effect, the cannons of scientific discovery. However, no such set of inductive rules is available. There is no known logical procedure for inductively formulating a new general statement from sets of antecedently collected separate observations. In Hempel words, “the transition from data to theory requires creative imagination. Scientific hypotheses and theories are not derived from observed facts, but are invented in order to account for them.”
Research Design and Procedures
A nonequivalent control-group design (Compbell & Stanley, 1963) was used to examine the differences between the experimental- and control-group subjects in regard to their understanding of the NOS. Two instruments have been used, they are VOSTS TVNOS (Lin, 2000) and (Aikenhead, 1989). In this design, three groups of teachers were given a pretest and posttest on the TVNOS in the first year, on the TVNOS and VOSTS in the second year for different participants. The pretest was administered at the beginning of the academic school year. Each group was tested again at the completion of the same school year, following 14 weeks instruction.