Classifying Quadrilaterals

Lesson Plan - Get It!

Audio:

Polygons with four sides are called quadrilaterals.

Parallelograms, rhombuses, trapezoids, squares, and rectangles are quadrilaterals. On a piece of paper, draw an example of these shapes and describe the properties of each shape out loud.

Quad means four and lateral means side. Quadrilaterals have these special properties:

• four sides and four corners
• 2-dimensional (flat shape)
• straight sides
• closed shape

Quadrilaterals can also have parallel sides — sides that stay the same distance apart and never cross each other. The interior, or inside, angles add up to 360 degrees.

As you watch Math Antics - Quadrilaterals, from mathantics, write down one special property about each quadrilateral:

• square
• rectangle
• rhombus
• parallelogram
• trapezoid

Next, review this quadrilateral chart so you can become more familiar with each shape:

Example 1

Name the quadrilateral and explain your reasoning:

This shape has four sides and four right angles, which are 90 degrees each. The opposite sides are parallel and of equal length, so this quadrilateral is a rectangle.

The tick marks on the sides of the rectangle help you see that the opposite sides are equal. The sides with one tick mark mean that those two sides are equal length and the same is true for the opposite sides with two tick marks, even though the actual measurements are not given.

Example 2

The following shapes are not quadrilaterals. Explain why they are not quadrilaterals:

Quadrilaterals have only four sides and have straight sides. The first figure has more than four sides and is three-dimensional. The second figure has more than four sides. The third figure does not have straight sides.

• Can a quadrilateral have 5 sides? Why or why not?
• What special features are used to classify a quadrilateral?

In the Got It? section, you will play games and complete interactive practice to classify quadrilaterals.