What are Quadrilaterals?

Nico and Nia 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 directions. 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, four things must always be true: It must have four straight sides, four corners, be fully closed, and be two-dimensional, or flat. These are called defining attributes 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 characteristics are called non-defining attributes. So, quadrilaterals can be any color, size, or face any direction. Let's use this checklist to see which glow in the dark quadrilaterals we need to put the extra sticky tac on. First, we need to determine if this shape has all four defining attributes of a quadrilateral. It has four straight sides. It has four corners. It is closed and it's two dimensional. This shape IS a quadrilateral because it meets all four defining attributes. Let's put extra sticky tac on it. Take a look at this shape: does it have all four defining attributes 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 since it can't meet all the requirements. This shape does not need extra sticky tack. Let's look at THIS shape now. Does it meet all four defining attributes of a quadrilateral? It has four straight sides. It has four corners. It is closed and it's two dimensional. This shape IS a quadrilateral because it meets all four of the defining attributes. Let's put extra sticky tack on it. Now, try this shape on your own. Use the checklist to see if the shape meets all four defining attributes. 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 corners. 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 four defining attributes: four straight sides, four corners, be fully closed and be two-dimensional. However, the size, color, 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!"