The Effects of Cabri Geometry for
Exploring Geometry in Classroom
Tuyosi
Nomura
t-nomura@ma3.justnet.ne.jp
Board of Education in Yuki City Japan
Japan
Abstract
In order to develop students' logical and
mathematical reasoning, geometrical proof has been part of the junior high schools'
mathematics curriculum in Japan; but recent research reported that only about
twenty percent (20%) of students are able to solve geometrical
proof-problems. The fact that many
students could not succeed in writing a proof does not mean that they could not
develop logical and mathematical reasoning. For developing their reasoning, the
exploration of constructions must be taught a different way. Dynamic Geometry
Software, like Cabri Geometry (Cabri) offers a new environment for exploring constructions.
This paper discusses the change of reasoning that occurs using Cabri for the learning
of geometry. Junior high school students, from twelve to fifteen years old,
studied geometry using Cabri. Their change of reasoning is discussed from the
following points: exploring the basic constructions in a different way than that
of the text book, which could not be observed in the classroom before Cabri;
and exploring and understanding the proposition before the proof. It was
believed that proof was the only way to understand a proposition in the
geometry classroom. But Cabri offers a different way of exploring figures, and
also helps students' reasoning from the proposition to the conclusion. Through
three years in-class observation, this study points out three major effects of
using Cabri: visualizing the character of a figure clearly, a better
understanding of the meaning of the theorem, and making clear what the students
should be proving.
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