TI-84 Tutorial: Building Geometric Foundations for the Primary Grades Using Calculator-Based Cabri

Abstract

This tutorial demonstrates techniques to enhance student learning through the integration of calculator-based Cabri geometry activities and experimentation. Examples and activities from courses for prospective primary teachers illustrate the interconnection of the activity materials and corresponding pivotal steps in the development of geometric understanding. The activities highlight how geometric concepts can be experimentally developed to enhance future primary school teachers' understanding of key geometric results.

Tutorial participants work with TI-84 calculators on four sets of Cabri Junior activities. To introduce the activities an instructor demonstrates how to open the calculator files used in the activities, how to construct straight objects associated with a given triangle, and how to animate the triangle and its associated straight objects. After the introduction, the participants use Cabri's animation feature to complete tasks and answer questions about the objects they construct. In each of the activities, prepared files enable the tutorial participants to animate the triangle and the constructed straight objects, and to observe changes in the positions of concurrent points and in the measures of the vertex angles.

Concluding activities provide opportunities for extensions by constructing triangles formed by the concurrent points and vertices of the original triangle. The participants then construct and measure interior triangles and make conjectures based on these measures. The last part of the tutorial provides participants an opportunity to compare their assessments of the activities with those of recent classrooms of prospective primary school teachers. Commentaries from those classes emphasize the ease in using these activities to explore, generalize, conjecture, and make connections between disparate geometric phenomena. Comments from in-class instructors provide evidence that students gain a deeper understanding of the geometry in the sense that they are better at formulating interpretations and visualizing situations with Cabri. Finally, remarks from both prospective teachers and their in-class instructors indicate that these teaching applications facilitate new insights and excitement about the teaching of geometry.