Chapter 15 Lesson 3 Quadrilaterals and Other Polygons

A polygon  is a flat, closed figure that is made up of three or more straight line segments called sides.  FLAT  CLOSED  3 or MORE STRAIGHT SIDES

A vertex  is the point where two sides of a polygon meet.  Show me a vertex!  Hint- Remember the Very, Very Tickly spot?

A polygon can be named by the number of sides it has. These Are Polygons:

Triangle “tri” means 3  3 sides  3 angles

Quadrilateral “quad” means 4  4 sides  4 angles

Pentagon “pent” means 5  5 sides  5 angles

Hexagon “hex” means 6  6 sides  6 angles

Octagon “octo” means 8  8 sides  8 angles

These Are Not Polygons: Can you tell me why?

Some Quadrilaterals Have Special Names

A rectangle  has opposite sides that are parallel  four right angles.

A square  has four sides of the same length  four right angles

A trapezoid  has only one pair of parallel sides. What does that sound like? TRAP reminds me of a trap that gets skinnier and skinnier as you go in! Then, POOF! You are trapped!

A parallelogram  has opposite sides that are parallel.

A rhombus  has opposite sides parallel  four sides of the same length.

Quadrilateral Game Each student needs to get one dice, a pencil, and a piece of paper.

You and the person across from you are partners. If we have a group of 3, that is fine too!

Take turns rolling the dice and name the figure that has that many sides. ( 1 and 2 rolls do NOT make quadrilaterals. Skip to the next player.)

See how many you can quietly get right in the next 2 minutes.