During the 1920s, a biologist named Jean Piaget proposed a theory of cognitive development of children. He caused a new revolution in thinking about how thinking develops. In 1984, Piaget observed that children understand concepts and reason differently at different stages. Piaget stated children's cognitive strategies which are used to solve problems, reflect an interaction BETWEEN THE CHILD'S CURRENT DEVELOPMENTAL STAGE AND experience in the world.
Research on cognitive development has provided science educators with constructive information regarding student capacities for meeting science curricular goals. Students which demonstrate concrete operational thinking on Piagetian tasks seem to function only at that level and not at the formal operational level in science. Students which give evidence of formal operational thinking on Piagetian tasks often function at the concrete operational level in science, thus leading researchers to conclude that the majority of adolescents function at the concrete operational level on their understanding of science subject matter. In a study by the National Foundation of subjects in Piaget's Balance Task were rated as being operational with respect to proportional thought development. In addition, seventy-one percent of subjects did not achieve complete understanding of the material studied in a laboratory unit related to chemical solubility. The unit delt with primary ratios and proportions, and when overall physical science achievement was considered, about forty-three percent of the formal operational studies were not able to give simple examples of the problem that were correctly solved on the paper and pencil exam (Inhelder & Piaget, 1958, p. 104).
Piaget was primarily concerned with the developmental factors that characterize the changes in the child's explanations of the world around him or her. Piaget's early research showed
three parallel lines of development. First, from an initial adualism or confusion of result of the
subject's own activity with objective changes to reality to a differentiation between subject and object. Second, from a phenomenological interpretation of the world to one which is based on objective causality. Third, from a unconscious focusing on one's own point of view to a decentration which allocates the subject a place in the world alongside other persons and objects. In functional terms, these concepts are termed assimilation and accommodation in reference to interaction with the physical world, and socialization in reference to interaction with other people (Inhelder & Sinclair, 1974, p.22).
Piaget's states many secondary level science courses taught in the past at the have been too abstract for most students since they are taught in lecture or reception learning format. Thus, students who only have concrete operational structures available for their reasoning will not be successful with these types of curricula. Programs using concrete and self-pacing instruction are better suited to the majority of students and the only stumbling block may be teachers who cannot understand the programs or regard them as too simplistic. Since the teacher is a very important variable regarding the outcome of the science, the concern level of the teacher will determine to what extent science instruction is translated in a cognitively relevant manner in the classroom.
Educators who prefer to have children learn to make a scientific interpretation rather than a mythological interpretation of natural phenomena, and one way to introduce scientific interpretations is to analyze any change as evidence of interaction. One way in which this teaching device can function is if there is an instructional period of several class sessions in which the students are engaged in "play" with new of familiar materials; followed by is a suggestion of a way to think about observations; lastly there is a further extermination in which the students can explore the consequences of using their discoveries . Through the process of guided discovery, the student
goes from observation at the beginning to interpretations at the end (Athey & Rubadeau, 1970, p. 245).
In Piaget's study of the operations that underlie the system of scientific concepts related to number, measurement, physical quantities, and logical classes and relations, structural models were needed to explain the processes involved in the formation of these concepts (Inhelder & Sinclair, 1974, p. 23). The grouping of classes and relations describe the characteristics of the end product of process of growth as a particular system of mental operations. The logical and infralogical systems of concrete thought prolong the action structures of the