Quadrilaterals

Nico and Nia have bought glow-in-the-dark shapes to stick to the attic ceiling! They can't wait to put them up, but first they must read the instructions. The directions say to put extra sticky-tack on the quadrilaterals but Nia and Nico don't know what a quadrilateral is! Let's help them by learning about quadrilaterals! Quadrilaterals are special flat, four sided shapes. The quad part of the word, quadrilateral, means four. In order for a shape to be called a quadrilateral, these things must always be true: It must have four straight sides, four angles, four vertices, be fully closed and be two-dimensional, or flat. These are called the shape's properties and can never change, if a shape is to be called a quadrilateral. They are characteristics that have to stay the same. However, some characteristics can change and the shape can still be called a quadrilateral. These are features that a quadrilateral may have. Quadrilaterals can be any colour size, or face any direction. Let's use this checklist to see which glow in the dark stickers are quadrilaterals that need extra sticky-tack. First, we need to determine if this shape has all the properties that are characteristic of a quadrilateral. It has four straight sides. It has four angles. It has four vertices. It is closed and it's two dimensional. This shape is a quadrilateral because it has all these properties. Let's put extra sticky-tack on it. Now look at this shape, does it have all the properties of a quadrilateral? It does not have four straight sides, it has ten. This shape does not have four sides so we can stop checking as it does not have all the requirements. This shape does not need extra sticky-tack. Let's look at this shape now. Does it have all the properties of a quadrilateral? It has four straight sides. It has four angles. It has four vertices. It is closed and it's two dimensional. This shape is a quadrilateral because it has all of these properties. Let's put extra sticky-tack on it. Now, try this shape on your own. Use the checklist to see if the shape has all the properties of a quadrilateral. Is this shape a quadrilateral? This shape is not a quadrilateral. While it is closed and its sides are straight, it has more than four sides and more than four vertices. It's also not flat, it's three dimensional! So this shape does not get extra sticky-tack. While Nico and Nia continue to sort through the other shapes, let's review. Today we learned about quadrilaterals. In order for a shape to be called a quadrilateral, it must have these important properties: four straight sides, four angles, four vertices, be fully closed and be two-dimensional. However, the size, colour and direction of a quadrilateral can change. "That's the last one. Nico, can you hit the lights?" "I think I want to make a wish!"