We now begin to think about shapes made from four straight lines. All such shapes are called quadrilaterals.

Some quadrilaterals have special names, depending on the lines and angles used to form them.

The simplest shape is a trapezium. It has one simple property:

If just two of its sides are parallel, it is a trapezium.

The shape enclosed by the four lines in the diagram is a trapezium, because there are just two lines that are parallel.

Remember the rules about parallel lines and angles, and how we know whether two lines are parallel as we move on to make a trapezium for ourselves.