Kalyani Raghavan

Scientific Reasoning Across Different Domains

This study seeks to establish which scientific reasoning skills are primarily domain-general and which appear to be domain-specific. The subjects, 12 university undergraduates, each participated in self-directed experimentation with three different content domains. The experimentation contexts were computer-based laboratories in d.c. circuits (Voltaville), microeconomics (Smithtown), and the refraction of light (Refract), Subjects spent three 1-1/2 hour sessions working with each laboratory and took pretests and posttests that assessed their learning. Specific patterns of strategies used in each laboratory depended primarily on the structural form of the discovery task and the nature of the domain. In a situation that required the discovery of correlational regularities, evidence-generation activities, like the heuristic of controlling variables, were primary. In contexts where the regularities were functional rules, evidence interpretation became important. When the rules were quantitative, mathematical and algebraic heuristics were important. Students appeared very sensitive to the task demands of each laboratory, and adjusted their strategies accordingly. Regardless of this adaptation to specific conditions, they learned more as they proceeded from domain to domain, indicating that they were becoming more effective in planning and carrying out experiments, and in formulating and testing hypotheses based on those experiments. The findings suggest that the most generally useful skills for direct instruction may be those for evaluating the kind of problem at hand and for selecting the most appropriate processes and strategies.

Why Does It Go Up? The Impact of the MARS Curriculum as Revealed through Changes in Student Explanations of a Helium Balloon.

The Model-Assisted Reasoning in Science (MARS) project created a model-centered, computer-supported sixth-grade science curriculum organized around the theme balance of forces. To help monitor effectiveness during implementation in a public middle school, individual student interviews were conducted after each of the curriculums three sections. In each interview, students were asked to explain why a helium balloon floats up. This article describes an analysis of student responses to the balloon question and what it reveals about the impact of the curriculum. The article begins with an overview of research on childrens ideas about floating and sinking. Following a description of MARS instruction, procedures used to analyze responses to the balloon question are described, and results of the analysis are presented and discussed. The article concludes by examining implications for science education. J Res Sci Teach 35: 547–567, 1998.

The Impact of the MARS Curriculum on Students' Ability to Coordinate Theory and Evidence.

The Model-Assisted Reasoning in Science (MARS) project seeks to promote model-centered instruction as a means of improving middle-school science education. As part of the evaluation of the sixth-grade curriculum, performance of MARS and non-MARS students was compared on a curriculum-neutral task. Fourteen students participated in structured interviews in which they experimented with a balance apparatus that provided three manipulable variables (two affected balance, one was a non-causal distractor variable). Although both groups were equally able to identify and test variables, all MARS students discovered a quantitative rule to describe the operation of the balance, whereas only one non-MARS student did so. MARS students discovered this numerical relationship through experimentation, regardless of their scientific reasoning profile (i.e. theory-generating, theory-modifying, or theory-preserving). The critical components of MARS instruction that may foster the ability to flexibly coordinate theory and evidence include multiple opportunities to draw conclusions from data and an emphasis on the successive refinement of models.

Studying and Teaching Model-based Reasoning in Science

A model-centered science curriculum is developed and implemented to help middle school students learn to reason with qualitative explanatory models that underlie scientific phenomena. The curriculum focuses on concepts important for understanding floating and sinking, coordinating traditional laboratory experiments with interactive computer tasks which permit students to inspect, manipulate and predict with models of the underlying theoretical entities.