Primary 3 maths · Geometry · About 10 minutes
Recognise perpendicular and parallel lines
Extend the lines mentally and check the right-angle mark or equal spacing.
Start the interactive lesson →Open practice activity
What you will learn
- Recognise perpendicular and parallel lines
Models used: number sentences, stories, diagrams.
Look at the space between the lines
These horizontal lines stay the same distance apart. They are parallel.
These horizontal lines stay the same distance apart. They are parallel.
Turning the page changes orientation but not the relationship. Crossing alone does not guarantee perpendicular lines.
Two parallel lines These lines meet at a square corner. They are perpendicular.
Two perpendicular lines In a rectangle, opposite sides are parallel. Neighbouring sides meet at right angles.
Look for both relationships in a rectangle
What did the picture help us see?
In a rectangle, opposite sides are parallel. Neighbouring sides meet at right angles.
Worked example: A new example, together
Which relationship do the marked lines show?
Extend the lines mentally and check the right-angle mark or equal spacing.
Perpendicular lines meet at a right angle.
A square mark indicates a right angle. Locate the right-angle mark.
A square mark indicates a right angle. Which relationship do the marked lines show?
perpendicular
Locate the right-angle mark.
A square mark indicates a right angle. A right angle measures 90°.
A square mark indicates a right angle. The relationship is perpendicular.
A square mark indicates a right angle. Check the result against the question we started with.
Each of the four angles at the intersection is 90°.
We found perpendicular. Perpendicular lines meet at a right angle.
A square mark indicates a right angle.
Common mistakes to discuss
- Lines that look close are parallel. Parallel lines stay exactly the same distance apart however far they are extended, and never meet.
Check your understanding
- Recognise perpendicular and parallel lines
- recognise or construct line relationships independent of orientation
- check the answer against the original quantities and units
Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.
Try this lesson →Related Primary 3 lessons
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