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This article describes an investigation into the effects of instruction using microcomputer simulations and conceptual change strategies. The microcomputer program was designed in accord with a model of conceptual change to diagnose and remediate an alternative conception of velocity. Results show that, first, the microcomputer simulations are credible representations of reality, and second, that the remedial part of the program produced significant conceptual change in students holding the alternative conception.

Journal of the Learning SciencesPublication details, including instructions for authors and subscription information:Although it is common to see extreme case reasoning included in lists of expert heuristics for problem solving, little work has been reported on the role that extreme cases can play in learning that leads to conceptual change. Evidence is presented from video tapes of think-aloud tutoring sessions to document the learning from extreme cases in a unit about levers for seventh graders. The observations support the view that one role of extreme cases is to provide a firm data point or comparison that helps students to establish an ordinal relation between two given variables. Two new additional roles for extreme cases in fostering learning are also identified: (a) their role in activating an intuition, often in the form of a perceptual motor schema, that is used in constructing an imageable, intuitively, grounded, explanatory model as opposed to an empirical rule; and (b) their role in facilitating the formation of new causal variables. Pending confirmation of similar effects in other subject areas, these roles are candidates for being included in a set of general learning strategies for science instruction. This illustrates the function that "learning-aloud studies can play in documenting new types of learning processes and instructional strategies. The study highlights the importance for instructional design of research that uncovers students' existing knowledge structures and natural reasoning processes. The study suggests that explanatory model construction, causal relation construction, and concept formation can result from such instructional designs. The extent to which t!lese three outcomes are evidence for strong conceptual change is also discussed. Requests for reprints should be sent to John Clement, Scientific Reasoning

An Experimental Astronomy Curriculum or Thinking Journey was developed on the basis of a combination of Constructivism and Mediated Learning Experience (MLE). The Thinking Journey was designed to serve as a vehicle for promoting a process of conceptual change in a wide range of students. Its theoretical background, curriculum and an experiment to test its effectiveness with a class of low functioning high school girls are documented here. The study included an experimental (E) and control (C) group, each of which comprised 16 9th grade students. E focused on the concept of Earth within the framework of the Thinking Journey, while C was exposed to the conventional approach to the study of Earth within the Earth Studies curriculum. The results indicated the relative effectiveness of the Thinking Journey in promoting a process of positive change in the students' conceptualization of Earth, improving their knowledge of astronomy, enhancing their general scientific knowledge and developing their cognitive functioning and problem solving abilities. These findings are discussed in terms of the usefulness of utilizing a scientific subject as part of an educational intervention designed to enhance the cognitive abilities of low functioning students.