New
New
Year 5
Know that the angles on a straight line sum to 180 degrees and use this to solve problems
I know that the angles on a straight line sum to 180 degrees and use this to solve problems.
New
New
Year 5
Know that the angles on a straight line sum to 180 degrees and use this to solve problems
I know that the angles on a straight line sum to 180 degrees and use this to solve problems.
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Lesson details
Key learning points
- Angles on a straight line have a sum of 180 degrees.
- To calculate missing angles you can use addition and subtraction.
- Use mental or written strategies to calculate with angles up to 180 degrees.
Keywords
Sum - The sum is the result of adding two or more numbers.
Opposite - If something is opposite, it is placed on the other side.
Common misconception
Pupils think that the angles on a straight line only applied to lines that are horizontal.
Ensure pupils are exposed to straight lines in a range of orientations, encouraging them to draw on the 180 degree angle and how this can apply to both sides of the straight line.
You might like to create two straight lines that are joined by a split pin at the centre. Slowly rotate one of the lines around to reveal the angles it creates. Once pupils know the size of one of the angles, they can then identify the other angles by beginning to generalise about opposite angles.
Teacher tip
Licence
This content is © Oak National Academy Limited (2025), licensed on
Open Government Licence version 3.0
except where otherwise stated. See Oak's terms & conditions (Collection 2).Starter quiz
Download starter quiz
6 Questions
Q1.
Look at the hands on this clock face and the arrow. The angle formed is __________.

a right angle
obtuse
reflex
Q2.
It is 2 o’clock. Imagine the clock now shows half past two. How has the minute hand turned?

A quarter turn
Three-quarter turn
A full turn
Q3.
180° is the same as __________.
a quarter turn
three quarters turns
a full turn
Q4.
The image is not to scale. The image shows part of a right angle. What is needed to complete the right angle? °

Q5.
What is the missing value in this bar model? °

Q6.
The image is not to scale. What is the value of missing angle a? a = °

Exit quiz
Download exit quiz
6 Questions
Q1.
The image is not to scale. What is the value of missing angle a? a = °

Q2.
The image is not to scale. What is the value of missing angle a? a = °

Q3.
The image is not to scale. What is the value of missing angle a? a = °

Q4.
The image is not to scale. What is the value of missing angle p? p = °

Q5.
The image is not to scale. What is the value of missing angle p? p = °

Q6.
The image is not to scale. What is the value of missing angle c? c = °
