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How the derivative becomes visible: the case of Daniel

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2007-06-01
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Copyright (c) 2007 Markus Hähkiöniemi

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This work is licensed under a Creative Commons Attribution 4.0 International License.

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Hähkiöniemi, M. (2007). How the derivative becomes visible: the case of Daniel. Teaching Mathematics and Computer Science, 5(1), 81-97. https://doi.org/10.5485/TMCS.2007.0140
Abstract
This paper reports how an advanced 11th-grade student (Daniel) perceived the derivative from a graph of a function at a task-based interview after a short introduction to the derivative. Daniel made very impressive observations using, for example, the steepness and the increase of a graph as well as the slope of a tangent as representations of the derivative. He followed the graphs sequentially and, for example, perceived where the derivative is increasing/decreasing. Gestures were an essential part of his thinking. Daniel's perceptions were reflected against those of a less successful student reported previously [Hähkiöniemi, NOMAD 11, no. 1 (2006)]. Unlike the student of the previous study, Daniel seemed to use the representations transparently and could see the graph as a representation of the derivative.