Education Technology

Cross-Fencing Pastures

Published on 06/09/2008

Activity Overview

In this activity, students use the Geoboard to determine the areas of polygons by dissecting them into parts that are squares, rectangles, and triangles.

Before the Activity

  • Start the Geoboard App and format it
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 51 - 60 from the attached PDF file for your class
  • During the Activity

    Distribute the page to the class.

    Follow the Activity procedures:

  • Construct a hexagon and find its area by counting squares and half squares


  • Find the area of a trapezoid by using a surrounding rectangle and check the answer using the calculator
  • Find the area of the trapezoid by dividing it into rectangles and triangles


  • Dissect triangles and ensure that every smaller triangle has at least one vertical or horizontal line segment as one of its sides, so that both the base and height of each triangle are whole numbers


  • Draw given shapes on the geoboard and find their area by using the dissection method
  • After the Activity

    Student complete the Activity sheet and answer questions.

    Review student results:

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