TI84
Tutorial: Building Geometric Foundations for the Primary Grades
Using CalculatorBased Cabri
Beverly Ferrucci
bferrucc@keene.edu
Mathematics
Keene State College
Jack Carter
jcarter@csuhayward.edu
Mathematics & Computer Science
California State University
United States
Abstract
This tutorial demonstrates techniques to enhance
student learning through the integration of calculatorbased 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 TI84 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 inclass 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 inclass instructors indicate that these teaching applications
facilitate new insights and excitement about the teaching of geometry.
