Angles: kinds and measuring with a protractor
Name angles and measure them with a protractor, to the nearest degree. Read one step, play with it, then tap “I understand this”.
An angle is a turn
An angle forms where two lines (the arms) meet at a point (the vertex). The further one arm turns, the bigger the angle. We measure angles in degrees (°).
The angle maker
Turn the blue arm and watch the name change.
A full turn is 360°, a half turn 180° and a quarter turn 90°.
The ancient Babylonians divided the circle into 360 parts, almost like the 365 days of a year. 360 divides neatly into halves, thirds, quarters, fifths, sixths and more, so it is easy to work with.
The kinds of angles
Always compare with a right angle (the corner of a page): smaller is acute, bigger is obtuse.
Name the angle
Which kind of angle?
Look at the yellow turn and choose the name.
Correct: 0Angles around us
A rectangle and a square have four right angles. The hands of a clock make angles too: between two numbers is 30°.
Clock angles
Change the hour and look at the angle between the hands.
Make an angle tester: fold a piece of paper twice; the corner is a perfect right angle. Hold it against any angle to compare.
Measure with a protractor
- Put the centre of the protractor exactly on the vertex.
- Line up the 0 line along one arm of the angle.
- Read where the other arm crosses. Use the scale that starts at 0 on your arm.
- Check: if it is an acute angle, the number must be smaller than 90.
A protractor has two scales. If you read 120° for an acute angle, you used the wrong scale: it is 60°.
In the angle maker at step 1 you can see a protractor scale behind the angle.
An angle can open to the left or to the right. The scale that starts at 0 on your arm counts how far the other arm has turned away from yours.
Check yourself
- Angles are measured in degrees (°). Full turn 360°, half turn 180°.
- Acute < 90° · right = 90° · obtuse between 90° and 180° · straight = 180° · reflex > 180°.
- Always compare with a right angle (the corner of a page).
- Protractor: centre on the vertex, 0 on one arm, read on the same scale.
Write these points in your maths book. Read them again the night before the test.
Quick questions
Tap an answer. If you get one wrong, read why and go back to that step. You get new questions every time.
You ticked all 5 steps! Now you are ready for the quiz.- Practice sheet for this classQuestions + memo · 2 A4 pagesPractice sheet
- Geometry8 pages · PDFPaperMemo
- Space and shape8 pages · PDFPaperMemo
Ready for more? The Grade 6 geometry quiz gives you new questions every time.
- One step a day is enough. Ten calm minutes work better than an hour the night before the test.
- Find right angles at home together (doors, windows, books) and an obtuse angle (an open laptop).
- Ask your child to tell you the rule in their own words. If they can explain it, they understand it.
- The ticks (“I understand this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 6 Maths. Always check your teacher’s notes and textbook too.