Activity Overview
Students explore the properties of triangles formed by connecting the midpoints of two sides of a triangle, and examine the relationship between the two triangles. They study the Triangle Midsegment theorem.

Before the Activity
Install the Cabri™: Jr. App on the students' graphing calculators using one of these two methods:

TI-Connect™ , a TI Connectivity Cable, and the Unit-to-Unit Link Cable
TI-Navigator™ "send to class" feature
See the attached PDF file for detailed instructions for this activity
Print pages 31 - 35 from the attached PDF file for your class

During the Activity
Distribute the pages to the class.
Follow the Activity procedures:

Draw a triangle and label its vertices
Construct a midsegment by joining the midpoints of two sides of the triangle
Check whether the midsegments are parallel to their opposite sides
Measure the length of the midsegment and the length of the opposite side of the original triangle
Observe that the midsegment is half the length of the opposite side
Drag one of the vertices to alter the triangle
Verify that for all triangles, a midsegment is parallel to the opposite side and length of the midsegment is half that of the opposite side
Find the perimeter and area of the original triangle and the midsegment triangle
Alter the triangle and tabulate the perimeter and area of the original triangle and the midsegment triangle
Observe that the perimeter of the midsegment triangle is half the original triangle
Note that the area of the midsegment triangle is one fourth that of the original triangle
Measure the angles of the midsegment triangle and the original triangle
Alter the triangle to create an acute triangle, an obtuse triangle, and then a right triangle
Notice that the type of triangle formed by the midsegments is the same type of triangle as the original triangle

After the Activity
Review student results:

As a class, discuss questions that appeared to be more challenging
Re-teach concepts as necessary