The Hidden Hand that Shapes Conceptual Understanding: Choosing Effective Representations for Teaching Cell Division and
In interviews within our studies, students revealed their conceptions of cell division and climate change. Their conceptions of these topics are far from the current scientific theory, but they still make sense to the students. Employing the theory of exp
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The Hidden Hand that Shapes Conceptual Understanding: Choosing Effective Representations for Teaching Cell Division and Climate Change Kai Niebert, Tanja Riemeier, and Harald Gropengießer
An Episode from a Teaching Experiment on Cell Division In this teaching experiment (Riemeier & Gropengießer, 2008), an onion, whose roots had grown into a water-filled jar, was shown to three girls aged 15 years. The girls were asked to describe what had happened with the onion. Initially, the students were surprised by this question. Roots and plants commonly grow—so what? When the researcher asked how onion roots grow, the girls enumerated conditions of growth like the need for water or nutrients. After a while, one girl remembered the cellular structure of the onion, whereupon all three students explained the growth of onion roots by multiplication of cells. The onion produces a lot of cells, and in the case of a sufficient number of cells, the human eye is able to see a root. This process of multiplying cells was named cell division by the students. The growing number of cells brings forth the growth of onion roots. One student outlined her conception in a drawing (see Fig. 16.1). At this point, a learning activity was offered to the girls. A bar of chocolate was shown, and the students were asked to break it into squares and subsequently compare this process to cell division. In doing so, the girls recognized that despite the increased number of chocolate pieces, the pieces were smaller than the whole bar of chocolate. “But in case of a cell, it wouldn’t yield anything; it would be the same size.” The girl assumed the cell would not divide in the sense of getting smaller but rather ending up with two cells of similar size: “It is more like copying itself.” The other students agreed upon this. After a while, one student pushed it a little bit further: “The cell divides itself in the middle and grows thereupon.”
K. Niebert (*) • T. Riemeier • H. Gropengießer Institute for Science Education, Leibniz Universita¨t Hannover, 30167 Hannover, Germany e-mail: [email protected]; [email protected]; [email protected] D.F. Treagust and C.-Y. Tsui (eds.), Multiple Representations in Biological Education, Models and Modeling in Science Education 7, DOI 10.1007/978-94-007-4192-8_16, # Springer Science+Business Media B.V. 2013
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Fig. 16.1 Drawing of cell division by a student aged 15 years
What Happened? A Brief Analysis of the Learning Episode At the outset, the students conceptualized “growth” as a normal process that happens perpetually. There was no need for them to explain this process. It just happens, if the conditions of growth are given. Later, however, cells came to mind, and the term cell division was used. Even though the students were using this scientific term, they adhered to its literal meaning. They thought of division and thus multiplication of cells exclusively. Thus, the students got the idea that more cells suffice to accomplish the growth of onion root
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