Igal Galili

Learners' Knowledge in Optics: Interpretation, Structure and Analysis.

This study explored high school and teacher-training college students knowledge of light, vision and related topics before and after commonly practised instruction. This knowledge was analysed and interpreted in the light of premises for the construction of alternative knowledge by learners of optics. A hierarchical structure was suggested to represent the collective conceptual knowledge of students in terms of facets and schemes of knowledge. ‘Abundance’ and ‘gain’ coefficients permitted quantitative description of the spread and alteration of the facets and schemes. In place of confronting misconceptions individually, schemes provide a basis for the design of more effective methods of instruction to challenge the fundamental patterns of alternative knowledge. Student misconceptions identified in other studies were included for comparison. On the basis of the study, suggestions are made for modifications in curricula to improve optics instruction.

Stages of children's views about evaporation

This paper presents research results which reveal a well‐defined hierarchy of views children employ about evaporation and relative science curriculum topics in elementary school in Israel. The sequential change of these views was studied, described and scaled on the age span of five to 14. Factors influencing this evolution and its testing were evaluated. The extent to which the method of research and context environment might influence the research results were also studied. The conceptual change of views regarding evaporation, taking place in childrens minds, shows a clear correlation with their cognitive development, their progress in operative knowledge‐namely, the usage of the conservation principle, and the adoption of an abstract model for air.

Mechanics background influences students’ conceptions in electromagnetism

The understanding of different aspects of the ‘field’ concept in electromagnetism was tested with high school students and prospective teachers of technological disciplines. Some of the observed difficulties could be interpreted as originating from the change in methodological approaches employed in different domains of physics: electromagnetism vis‐a‐vis mechanics. This may have encouraged students to misinterpret the nature of force interactions and work‐‐energy conversions in the presence of electromagnetic fields. Clarification of the rationale for introducing the ‘field’ concept, especially in its historical aspect, could be useful in coping with the teaching‐learning problems evidenced in this study and other research.

Students' conceptual change in geometrical optics

Educational research provides information on specific ways in which conceptual changes occur when students learn geometrical optics. Students’ ideas may be represented as clusters of ‘facets‐of‐knowledge’, each cluster specific to an optical setting. When students’ ideas undergo conceptual change these facets of knowledge are transformed. The resulting ‘hybrid knowledge’ incorporates ideas from classroom instruction as well as some beliefs students held prior to instruction. It appears that relevant pre‐instructional knowledge could be described within ‘holistic conceptualization’, while hybrid post‐instructional knowledge may be described in the framework of ‘image projection conceptualization’ (IPC) contrasting with the scientific view elaborated in ‘point to point flux mapping’, conceptualization. The transition from holistic conceptualization to IPC, neither of which is correct, is related to students’ incorrect interpretation of the light‐ray concept. Specific activities are suggested to encourage an...

The influence of an historically oriented course on students’ content knowledge in optics evaluated by means of facets-schemes analysis

We report on an experimental course in geometrical optics which heavily incorporates historical models accounting for light, vision, optical images, and others. The design and contents of the course were guided by previously elicited knowledge of high school students regarding optical phenomena. We utilized the course in a year-long experiment. The content knowledge of students expressed in a facets-scheme structure was compared with the same under regular instruction. We made qualitative and quantitative assessments based upon facets-scheme frequencies. Clear differences found in students’ conceptual knowledge may support the adopted rationale and teaching approach: using appropriately selected historical materials that address knowledge issues relevant for the students can significantly promote meaningful learning of the subject matter.

Motion implies force: where to expect vestiges of the misconception?

The reported progress of post‐instruction students in understanding the force‐motion relationship in classical mechanics might be partially caused by the kind of questions used in tests. Citing a parallelism with historical progress towards correct force‐motion understanding, this research points to the factors which might help to discover the vestiges of the naive views of motion in novice students, and explains the motivation of their ‘regression’ to the motion‐implies‐force preconception. Among the factors are the novel context of qualitative questions, and situations of nonzero acceleration, especially when velocity and force are unparallel. The understanding of these factors should help to foster genuine progress in students’ conceptual understanding as well as to provide its reliable check. The research sample included pre‐ and post‐instructional high‐school students, students of a University Pre‐academic Study Department and preservice teachers in a Technology Teachers College.

Weight versus gravitational force: Historical and educational perspectives

This paper discusses the existing dichotomy regarding the definition of weight and its implications in science education. The history and epistemology of the weight concept and its present status in instruction and students knowledge about weight are reviewed. The rationale of the concept of gravitational weight, currently accepted in many textbooks, is critiqued. Two mutually related implications stem from this study in science teaching: a conceptual distinction between weight and gravitational force; and replacement of the gravitational definition of weight by the operational one. Both innovations may improve the quality of science education.

The Effect of a History-Based Course in Optics on Students’ Views about Science

In light of the convincing claims extolling the multifaceted merit of the “genetic” (historical) approach in designing learning materials (Matthews 1994), we developed an experimental course in optics. We tested the new materials and determined their effectiveness in a year long course given in several 10th grade high school classes. A special feature, which soundly contrasted our course from a typical one, was its essential incorporation of historical contents: the ideas, views and conceptions which constituted the early understanding of light and vision. In this report, we present that part of the assessment which concerns the courses impact on the students’ views about science and some related technological and cultural issues. In our analysis, we used a special hierarchical organization to represent pertinent data. Strong differences were found between the views elicited in the experimental group and parallel data regarding students in the control group. In our view, this demonstrated the advantage of utilizing historical materials in an aspect which is additional to our first intention – to improve students’ disciplinary knowledge. Such materials naturally address issues of much broader general interest, appropriate for physics education as opposed to physics training. Touching on a variety of features of science the materialspositively effect students’ views about science.

FLUX CONCEPT IN LEARNING ABOUT LIGHT : A CRITIQUE OF THE PRESENT SITUATION

This study investigates high school students knowledge of natural phenomena related to the concept of light flux (seasons, illumination) after they had learned optics. It is suggested that such knowledge be represented as a hierarchical structure of schemes and facets. The two naive schemes that prevail in students knowledge fail to represent the formal scientific model for the subject. The problem of the student failure to account for the phenomena is analyzed from several aspects. It is shown that current curricula lack the required conceptual tools: light flux, illuminance, and the law of illumination, all of which have gradually disappeared from textbooks in recent years. Light rays provide the sole framework in the current teaching of geometrical optics. Historically, the paradigm of light rays has been succeeded by that of light flux. Didactic, cognitive, and ontological perspectives are discussed in relation to specific implementations in science curricula and instruction. The changes suggested might have a positive impact on prevention of many currently prevailing misconceptions in optics.

Children's operational knowledge about weight

This study explores childrens knowledge regarding weight in the age span of five to sixteen years. It appears that childrens views develop gradually from the tactile experiences. Thus, such schemes as ‘weight‐is‐a‐pressing‐force’, ‘weight‐is‐possessed‐exclusively‐by‐heavy‐objects’, ‘suspended‐substances‐are‐weightless’, ‘weight‐is‐heaviness‐to‐hold/move’, and others, are intuitively constructed at a young age. Childrens applications of these schemata might be mutually contradictory in different physical situations, being gradually, pushed by the ideas of weight conservation. As the transition of the knowledge status is continuous and not synchronized between different aspects of reality, the regular classification of children between ‘conservers’ and ‘nonconservers’ of weight is rather imprecise. Children can simultaneously employ different operational schemata and concept images with regard to the same physical concept or phenomenon. The study implies that the identification of weight with gravitation...