• Research in Mathematical Education
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• v.14 no.3
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• pp.211-218
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• 2010

It is a truism that mathematics is about relations (cf. [Halford, G. S. (1999). The properties of representations used in higher cognitive processes: Developmental implications. In: Sigel, I. E. (Ed.), The Development of Mental Representation: Theories and Applications (pp. 147-168). Mahwah, New Jersey: Erlbaum]). In this article we are considering few problems related to the Viviani's and Routh's Theorems. All Problems are connected by the relation which exists between the distances of the point inside the triangle to it sides. We show how reasoning about the relations could lead the student's problem solving process and give easy to understand solutions of the problems. Among the problems being considered are the proof of the Converse to Viviani's Theorem, the formulas for areas of all figures formed by the sides of triangle and its cevians.

• Communications of Mathematical Education
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• v.30 no.1
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• pp.23-46
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• 2016

This study is aimed to implement a preferred generalization classes for gifted students. By designing and applying the generalization lesson using GSP, we tried to investigate the characteristics on the class. To do this, we designed a lesson on generalization of Viviani theorem and applied to 13 8th grade students in a math gifted class. As results, we could extract five subjects as followings; mediating the conjecture by GSP and checking the pattern, misunderstanding the confirm by GSP as a proof and its overcoming, digressing from the topic and cognitive gap, completing the proof by incomplete conjecture, gap between the generalization and understanding generality. Based on this subjects, we discussed the educational implications in order to help implement a preferred generalization classes for gifted students.