Kinds of lines

1Straight and curved lines

A straight line does not bend. The edge of your ruler is straight. A curved line bends, like the Nyabarongo river on a map or the edge of a round plate.

2Which way does a line go?

A horizontal line lies flat, like the water of Lake Kivu on a calm day. A vertical line stands straight up, like a flagpole. A slanting line leans to one side, like a ladder resting on a wall.

3Two lines together

When there are two straight lines, we look at how they meet.

• Intersecting lines cross or meet at a point, like two roads meeting at a roundabout.
• Parallel lines never meet, however far you make them. They stay the same distance apart all the way, like the two side lines of the football pitch or the lines in your exercise book.
• Perpendicular lines meet at a square corner, called a right angle. The top edge and the side edge of your exercise book are perpendicular. We mark the square corner with a small square.

4How do you know lines are parallel?

Measure the gap between them in two places. If the gap is the same everywhere, the lines are parallel. If the gap gets smaller, the lines will meet somewhere, so they are intersecting.

Perpendicular lines are a special kind of intersecting line: they cross, and the corner is square.

Try it yourself

Work each one in your exercise book first. Then tap Show answer to check.