Home » Math Theory » What makes a Quadrilateral?

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The short answer to “what is a quadrilateral?” is that it is a four-sided polygon. In other words it is four-sided, two-dimensional enclosed shape with straight sides.

Your children will learn (typically in 5th Grade) that there are many different types of quadrilaterals and they can be arranged in a hierarchy based on their properties.

Discuss the relationship between the quadrilaterals with your children. Follow the arrows down to see how certain ones are also special types of others as they exhibit all their properties. For example, a square is a special type of rectangle. Indeed a square can be said to be a special case of all the other quadrilaterals shown in the table.

The table shows different types of special quadrilaterals arranged in a hierarchy.

Follow the arrows down (or up if your prefer) the table to view the various categories and sub-categories.

Square

A Square is a quadrilateral with equal-length sides forming four right-angles.