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Chapter One
The Nature of Science and the Science Curriculum The Nature of ScienceThe various fields of science all have their own special ways of knowing. However, for the purpose of planning appropriate assessments, the essentials of the natural sciences should be defined. The natural sciences are characterized by organized explanations incorporating both theoretical and empirical elements. Scientists attempt to construct theories that encompass as much factual and conceptual knowledge, including laws and principles, as possible. The construction of theories is a process involving the consideration of factual evidence, insightful questioning, creativity, and imagination. Atomic theory and evolution theory are good examples of modern scientific theories that are central to the sciences as ways of knowing. They are sources of new hypotheses and logical deductions that can be tested. As these theories are refined, they continue to stimulate new questions and hypotheses. As with other scientific theories, each time they come into play in experimental situations, they are again subject to testing and the possibility of refutation. Each success broadens their domain and increases their usefulness. Verification of theories does not ensure truth, but it does extend their usefulness in explaining natural phenomena. Useful theories enable an individual to make predictions under a specified range of conditions. Scientific theories must be able to be tested according to standards of evidence and logical argumentation set by the scientific community; they are central to the scientific way of knowing and guiding observation. When scientists observe natural phenomena, their observations are made within the context of existing scientific theories. Nonscientists holding different views may perceive the same phenomena, but through their subjective belief systems, may arrive at different conclusions. History is replete with examples of misunderstandings and miscommunication that are based, at least in part, on the use of different rules of observation. Science consists of both theoretical and experimental knowledge that is constructed by the creativity, knowledge, and world view of scientists. Experimentation plays an essential role in generating and verifying scientific information. New findings and results of scientific observation and experimentation accumulate, enlarging the base of present knowledge and laying the foundation for future learning. Usually, scientific knowledge is structured, forming a web of interrelated concepts, laws, and principles. Whereas sensory data are sometimes ephemeral, concepts are precisely formulated and are connected to other concepts or sensory data within a theory in multiple ways. Concepts without factual content (sensory data) are empty, whereas sensory data without concepts are difficult to understand and open to misinterpretation. None of the processes usually associated with science (for example, observing, measuring, classifying, deducing, inferring) is unique to science. However, in science, these processes are given meaning by the context of the subject matter under investigation. Hence, observations of a mealworm seemingly walking endlessly around the sides of a container have new meaning when mealworm anatomy, behavior, and physiology are understood. Likewise, the wiggly lines a physicist observes on a photographic negative of a cloud chamber remain wiggly lines to most observers, but they become important sensory data (facts) when the conditions under which the lines were produced are known. A goal of science education, therefore, is to help students recognize the difference between personal opinion and knowledge gained through scientific investigation and debate. Although the scientific disciplines are alike in their reliance on evidence, use of logic, and organization of factual information into concepts and theories, they differ with respect to what constitutes evidence, specific methods of investigation, and degree of quantification. And yet, "there are common understandings among [scientists] about what constitutes an investigation that is scientifically valid" (American Association for the Advancement of Science, 1989). This view of the nature of science has profound implications for assessment, as reflected in the criteria outlined in chapter 3. Because a major purpose of NAEP is to illuminate education policy, assessment of student science learning must take into account the science curriculum. Hence, the NAEP Science Assessment Framework is based on a consensus regarding desirable elements of science education against which student attainment is to be measured. In developing the Framework, the planning committee reviewed key blue-ribbon reports, examined exemplary practices, studied local and state-based innovations in science curricula, reviewed science education literature, and noted innovations emerging in other countries. Recent reports by government agencies and professional societies (National Science Board Commission on Precollege Education in Mathematics, Science and Technology, 1983; American Association for the Advancement of Science, 1989; National Science Teachers Association, 1989; National Research Council, 1990) express unanimity in their goals for science education. For example:
There also are similarities in the reports’ recommendations on the science curricula and instruction needed to achieve these goals, including:
The design of the NAEP Science Assessment Framework, although maintaining some conceptual continuity with the 1990 NAEP Science Assessment, takes into account current reforms in science education. It is also consistent with the science framework used for the 1991 International Assessment of Educational Progress and the science framework for the 1995 International Association for the Evaluation of Educational Achievement (IEA) assessments.
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