# Activities

• • • ##### Author 6-8

60 Minutes

• ##### Device
• TI-73 Explorer™
• ##### Other Materials
This is Activity 4 from the EXPLORATIONS Book:
Shaping Middle Grades Mathematics: Activities for Geoboard and the TI-73

Slide Along

#### Activity Overview

In this activity, students use the Geoboard to determine the areas of quadrilaterals between parallel lines.

#### Before the Activity

• Start the Geoboard App and format it
• See the attached PDF file for detailed instructions for this activity
• Print pages 37 - 46 from the attached PDF file for your class
• #### During the Activity

Distribute the page to the class.

• Construct two parallel line segments, with a distance of 5 units between them
• Between these two parallel lines build three different parallelograms with the same base of 1 unit and same height of 5 units
• Calculate the area of the parallelograms, and observe that it is the same as the area of a rectangle with the same height and base (5 square units)

• Draw three trapezoids between the parallel lines that have the same bottom base length of 2 units, top base length of 1 unit and height 5 units
• Calculate the area of the trapezoids
• Note the area of trapezoids is equal to 7.5 square units
• Observe that the area of quadrilaterals between parallel lines with same base and height area equal
• #### After the Activity

Review student results:

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