This activity is a based on an activity I saw in Exploring Geometry with the Geometer's Sketchpad.
Student will construct a trapeziod and then use rotation to create a parallelogram from the trapeziod. The follow up questions lead the student to derive the formula for the area of a trapeziod.
This activity really only takes one 45 minute class period and the students seem to have a better understanding of area after completing the activity.
Before the Activity
Print out and make copies of this TI Interactive file to use with the activity. A free demo copy of the TI Interactive program can be downloaded at the TI web site.
During the Activity
Be sure to use the QUAD tool to construct the trapeziod. If segments are used the area cannot be calculated
After the Activity
The students should be able (with some help) to come up with the formula for the area of a trapeziod from this activity.