Education Technology

Investigating Properties of Trapezoids

Activity Overview

Students draw trapezoids and investigate their properties. They derive the area formula for a triangle from the area formula for a trapezoid. They also investigate the terms: Isosceles trapezoid and Tessellation.

Before the Activity

  • See the attached PDF file for detailed instructions for this activity
  • Print page 5 from the attached PDF file for your class
  • During the Activity

    Distribute the page to the class.

    Follow the Activity procedures:

  • Determine 3 ways to draw a trapezoid and drag independent points to ensure that the figure remains a trapezoid
  • Note that the sum of all interior angles is 360 degrees
  • Find a relationship regarding angle measurement that appears to be true
  • Drag the vertex and observe the relationship
  • Determine 3 ways to construct an isosceles trapezoid
  • Find at least 3 properties that are true for all isosceles trapezoids
  • Drag a vertex along the shorter base till its length becomes zero and the trapezoid becomes a triangle
  • Explore how the area of the trapezoid can be used to find the area of the triangle
  • Find the relationship between midsegment of a trapezoid and a triangle
  • Use the Transformation tool to tesselate a trapezoid and observe the figure formed
  • After the Activity

    Review student results:

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