From the moment of birth infants begin to generate views about their new environment. As children develop, there is a need to construct meaning regarding how and why things behave as they do. And, long before children begin the process of formal education, they attempt to make sense of the natural world. Thus, children begin to construct sets of ideas, expectations, and explanations about natural phenomena to make meaning of their everyday experiences. The ideas and explanations that children generate form a complex framework for thinking about the world and are frequently different from the views of scientists. These differing frameworks are referred to in the literature as misconceptions, alternative conceptions, or alternative frameworks. Since the early 1970s, research in science education and cognitive science has enriched our understanding of the importance of the ideas and explanations that students possess prior to instruction. This research has direct implications concerning the nature of learning science, as well as the process of teaching science.

Prior Knowledge and Conceptions of Students

Teachers have always recognized the need to start instruction "where the student is." David Ausubel (1968) emphasized this by distinguishing between meaningful learning and rote learning. For meaningful learning to occur, new knowledge must be related by the learner to relevant existing concepts in that learner's cognitive structure. For this reason, Ausubel contends that, "The most important single factor influencing learning is what the learner already knows." Ausubel also commented on the importance of preconceptions in the process of learning, noting that they are "amazingly tenacious and resistant to extinction...the unlearning of preconceptions might well prove to be the most determinative single factor in the acquisition and retention of subject-matter knowledge."

Perhaps the most comprehensive interdisciplinary assessment of children's conceptions of science is the Learning in Science Project in New Zealand (Osborne & Freyberg, 1985). The following examples, from the work of the Learning in Science Project, exemplify conceptions that children ages 5 to 18 possess on a variety of topics, while contrasting those views with the scientific perspective.

Scientific Perspective: Living things are distinguished from nonliving things in their ability to carry on the following life processes: movement; metabolism; growth; responsiveness to environmental stimuli; and, reproduction.

Children's Views: Objects are living if they move and/or grow. For example, the sun, wind, and clouds are living because they move. Fires are living because they consume wood, move, require air, reproduce (sparks cause other fires), and give off waste (smoke).

Scientific Perspective: A plant is a producer.

Children's Views: A plant is something growing in a garden. Carrots and cabbage from the garden are not plants; they are vegetables. Trees are not plants; they are plants when they are little, but when they grow up they are not plants. Seeds are not plants. Dandelions are not plants; they are weeds. Plants are only things that are cultivated; the more food, water, and sunlight they get the better. Plants take their food from the environment. They have multiple sources of food. Photosynthesis is not important to plants.

Scientific Perspective: A current of electricity, or electric current, is a flow of electrically charged particles through a conductor.

Children's View: Electric current flows from battery to bulb and is used up.

Scientific Perspective: Force is a push or a pull on an object. A body remains at rest or in uniform motion unless acted upon by a force.

children's Perspective: A body requires a force to keep it in motion. Force is always in the direction of motion. There is no force acting upon a body that is not in motion.

Scientific Perspective: Gravity is a force between any two masses. Gravity depends on the size of the masses and the distance between their centers.

Children's Perspective: Gravity is something that holds us to the ground. If there was no air there would be no gravity. For example, above the earth's atmosphere there is no gravity, and you become "weightless". Gravity increases with height above the earth's surface. It is associated with downward falling objects.

Research related to students' conceptual reasoning and the elucidation of alternative frameworks has also been conducted on the following scientific concepts and/or topics: air and air pressure, density, dynamics, the earth, ecological matter cycling, energy, heat and temperature, light and vision, mechanics, natural selection, the particular nature of matter, and respiration and photosynthesis (readers interested in more comprehensive reviews should refer to Driver & Erickson, 1983; Driver, Guesne & Tiberghien, 1985; Gilbert & Watts, 1983; West & Pines, 1985; as well as publications available from The Institute for Research on Teaching).

Learning science for most students involves a process of conceptual change. Anderson and Roth (in press) note that students who achieve an understanding of a scientific topic successfully integrate accurate scientific knowledge with their own personal knowledge of the world. Research suggests, however, that many students fail to do this; instead, they view scientific knowledge as being separate and distinct from their personal knowledge. For these students science is merely a compilation of strange, obscure facts rather than a system of conceptual schemes for understanding their environment.

Formal science instruction does not change the alternative frameworks held by many students. In fact, while we have referred to alternative conceptions common to elementary school students have been found to exist among high school students and college students. We observe many adults who have conceptions that are substantially different from those of scientists. With this in mind, if preconceptions are as tenacious as Ausubel contends, how can teachers enhance the likelihood of conceptual development and thereby improve students' science conceptions?

Driver (1983) notes that the alternative conceptions that students have constructed to interpret their experiences have been developed over an extended period of time; one or two classroom activities are not going to change those ideas. She emphasizes that students must be provided time individually, in groups, and with the teacher to think and talk through the implications and possible explanations of what they are observing-and this takes time. Improving students' science conceptions may begin by recognizing that "less is more." That is, we may need to decrease the amount of new material introduced to students each year if we truly desire to enhance their conceptions of scientific phenomenon.

In teaching for conceptual change, students must experience conflict with their expectations. It is only reasonable that students would not accept a new idea with first feeling that their existing views are unsatisfactory in some way. Posner et. al. (1982) suggest that if students are going to change their ideas:

1. They must become dissatisfied with their existing conditions.

2. The scientific conception must be intelligible.

3. The scientific conception must appear plausible.

4. The scientific conception must be useful in a variety of new situations.

Teaching for conceptual change then, demands a teaching strategy where students are given time to: identify and articulate their preconceptions; investigate the soundness and utility of their own ideas and those of others, including scientists; and, reflect on and reconcile differences in those ideas. The Generative Learning Model (GLM) is a teaching/learning model that substantially provides this opportunity. In the GLM, the learner is an active participant in the learning context rather than an empty cup to be filled (refer to Osborne & Freyberg for a more detailed description of the Generative Learning Model). The GLM has four instructional phases aimed at enabling the learner to construct meaning. Using the GLM, a teacher:

1. Ascertains students' ideas, expectations, and explanations prior to instruction.
2. Provides a context through motivating experiences related to the concept.
3. Facilitates the exchange of views and challenges students to compare ideas, including the evidence for the scientific perspective.
4. Provides opportunities for students to use the new ideas (scientific conceptions) in familiar settings.

Teachers who effectively implement the GLM promote a learning environment that engages students in an active search and acquisition of new knowledge. Learning is characterized by a process of interaction between the student's mind and the stimuli providing new information. Such a learning environment enables students to modify their existing cognitive structures. Students experience a dynamic interaction between their preconceptions and the appropriate scientific conceptions.

The generative model for teaching/learning acknowledges a constructivist approach to the process of learning. That is, students construct meaning from their experiences. This is precisely how Piaget viewed the process or learning (1929/1969). Piaget referred to the process of acquisition and incorporation of new data into an existing structure as "assimilation" and the resulting modification of that structure as "accommodation." In learning science then, the new facts, ideas, and concepts that are acquired gain more meaning by being organized (assimilated) into a cognitive structure; at the same time, the existing cognitive structure is given further clarification and support, or perhaps even changed, by incorporating new information (accommodating itself to the new data). The instructional process to facilitating conceptual change must therefore: 1) identify and address students' alternative conceptions, 2) provide opportunities for students' ideas to evolve, and 3) enable students' new ideas to be applied in a context familiar to them.

Summary

If teachers are to improve students' science conceptions we must recognize that:

• students come to science class with ideas,
• students' ideas are often different from scientists,
• students' preconceptions are strongly held,
• traditional instruction (rote learning) will not lead to substantial conceptual change, and
• effective instructional strategies enable teachers to teach for conceptual change and understanding.

The key to altering the ideas, explanations, and conceptions of science that students possess is to find out and use what students already know. The challenge of teaching science is to ensure that you do not leave intact students' alternative conceptions or fill students with ideas and explanations which have little chance of being understood. The conceptual change teaching literature on generative learning may provide you with a solution to that challenge.

by William C. Kyle, Jr., E. Desmond Lee Family, Professor of Science Education, University of Missouri - St. Louis, St. Louis, MO and James A. Shymansky, Professor of Science Education, University of Iowa, Iowa City, IA 
 

References

Anderson, C. W., & Roth, K. J. (in press). Teaching for meaningful and self-regulated learning of science. In J. Brophe (Ed.), Teaching for meaningful and self-regulated learning. Greenwich, CT: JAI Press.

Ausubel, D. (1968). Educational psychology: A cognitive view. New York: Holt, Rinehart, & Winston.

Driver, R. (1983). The pupil as scientist? Milton Keynes, England: The Open University Press.

Driver R., & Erickson, G. (1983). Theories-in-Action: Some theoretical and empirical issues in the study of students' conceptual frameworks in science. Studies in Science Education, 10, 37-60.

Driver, R., Guesne, E., & Tiberghien, A. (1985). children's ideas in science. Philadelphia, PA: Open University Press.

Gilber, J. K., & Watts, D. M. (1983). Concepts, misconceptions and alternative conceptions: Changing perspectives in science education. Studies in Science Education, 10, 61-98.

Osborne, R., & Freyberg, P. (1985). Learning in science: The implications of children's science. Portsmouth, NH: Heinemann.

Piaget, J. (1929/1969). The child's conception of the world. Totowa, NJ: Littlefield, Adams, & Co.

Posner, G. J. Strike, K. A., Hewson, P. W., & Gertzog, W. A. (1982). Accommodation of a scientific conception: Toward a theory of conceptual change. Science Education, 66, 211-227.

West, L. H., & Pines, A. L. (eds.). (1985). Cognitive structure and conceptual change. Orlando, FL: Academic Press.