What are lines?
Lines are straight paths that go on forever in both directions. They do not curve or bend.
- A line can be shown with arrows at both ends.
- The edges of a long ruler can help you imagine a straight line.
Lines never stop. They do not have a beginning or an end, even though drawings show only part of them.
What are parallel lines?
Parallel lines are lines that stay the same distance apart and never meet, no matter how far they extend.
- Train tracks are parallel because they run side by side and do not cross.
- The sides of a rectangle show pairs of parallel lines.
If two lines go in the same direction and never touch, they are parallel.
What are perpendicular lines?
Perpendicular lines are lines that meet to form a right angle, which is a square corner.
- The corner of a piece of paper shows perpendicular lines.
- A plus sign (+) is made of two perpendicular lines.
A right angle looks like the corner of a book. When two lines form that corner, they are perpendicular.
What are intersecting lines?
Intersecting lines are lines that cross each other at one point.
- The letter “X” is made of two intersecting lines.
- Roads that cross each other show intersecting lines.
All perpendicular lines are intersecting, but not all intersecting lines form a right angle.
Using line relationships in real life
Understanding parallel, perpendicular, and intersecting lines helps you notice patterns, shapes, and structures in the world around you.
- Parallel lines help designers create neat and even patterns.
- Perpendicular lines help builders make strong corners and walls.
- Intersecting lines help mapmakers show streets and routes clearly.
When you look closely at objects, buildings, and drawings, you can find these different types of lines everywhere.