challenge problem" in a web-browser. A science challenge problem presents a phenomenon to be explained, along with indices to relevant resources. These are relatively ill-structured problems: at any given point many possible knowledge units may reasonably be considered. One side of the computer screen contains the representational tool, such as Threaded Discussion, Containment, Graph, or Matrix. The other side contains a web browser open to the entry page for the science challenge materials. Students seated in front of the monitor are asked to read the problem statement in the web browser. They are then be asked to identify hypotheses that provide candidate explanations of the phenomenon posed, and evaluate these hypotheses on the basis of laboratory studies and field reports obtained through the hypertext interface. They are asked to use the representational tool to record the information they find and how it bears on the problem. Analysis is based on transcripts of subjects' spoken discourse, gestures, and modifications to the interface; as well as measures of learning outcomes. A pilot study was conducted comparing MS Word (unstructured text), MS Excel (tables), and Belvedere (graphs), with two pairs of subjects run in each condition. The data is currently under analysis. Preliminary results are encouraging, and will be presented at the conference. Full studies have been funded and are in the planning stage.
The author is grateful to Micki Chi, Martha Crosby, and John Levinefor discussions concerning the role of representations in learning, visual search, and social aspects of learning, respectively; to many LRDC colleagues, including Alan Lesgold, Eva Toth, Arlene Weiner, for collaborations on the design of Belvedere; and to Cynthia Liefeld for assistance with the pilot studies. This work was funded by DoDEA's Presidential Technology Initiative and by NSF's Learning and Intelligent Systems program.
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