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You have named turns before: quarter turn, half turn, full turn. Now Ali swings his bedroom door open, from shut to wide open.
The swinging door makes an angle. What does the angle tell you?
Understanding angles
Recognise angles as a property of shape or a description of a turn
What a learner can do afterwards
- Identify angles at the corners of 2-D shapes
- Describe a turn (e.g. quarter turn, half turn) in terms of the angle made
- Explain that an angle measures the amount of turn between two lines meeting at a point
1 · Read
An angle is the space between two straight edges that meet at one point. A square has four corners, so it has four angles. A triangle has three corners, so it has three angles. Count the corners to count the angles.
Try it together
Ali swings his bedroom door open. A door that turns a little makes a small angle. A door that turns a lot makes a big angle. Two doors that turn the same amount make the same angle, whatever their size. A quarter turn, like a clock hand going clockwise from 12 to 3, makes a square corner angle.
From least to most turn: tiny turn, quarter turn, half turn, full turn. A full turn is four quarter turns. Keep going the same direction to turn more than a full turn.
Turns add up when you turn the same way. A quarter turn clockwise takes the hand from 12 to 3. A half turn clockwise takes it from 12 to 6. A full turn is four quarter turns. A quarter turn and a half turn clockwise take it from 12 to 9. From 3, a quarter turn clockwise reaches 6.
An angle is the corner a shape makes, or the amount something has turned: big turns make big angles, small turns make small angles.
Extra items and two readings are authored originals. Two readings are adapted from Khan Academy 'Right angles in shapes (informal definition)' and 'Angles in circles word problems'. Two videos are Khan Academy 'Recognizing angles' and 'Acute, right, & obtuse angles'.
2 · Watch
3 · Play
Take it off screen
Print a worksheetA4 with an answer key page for grown-ups. No screen, no internet.
Where it sits
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
Then practise
33 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.