New
New
Year 5
Estimate acute and obtuse angles using the standard unit of degrees
I can estimate acute and obtuse angles using the standard unit of degrees.
New
New
Year 5
Estimate acute and obtuse angles using the standard unit of degrees
I can estimate acute and obtuse angles using the standard unit of degrees.
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Lesson details
Key learning points
- You can estimate angles by comparing to a right angle of 90 degrees.
- Half a right angle is 45 degrees.
- One and a half right angles are 135 degrees.
Keywords
Estimate - To estimate is to find a value that is close enough to the right answer, usually with some thought or calculation involved.
Degree - A degree is a unit of measure for angles.
Common misconception
Pupils significantly over or under-estimate the size of angles, particularly when the initial line of the angle is not vertical or horizontal.
Encourage pupils to rotate the angle so that one of the lines is vertical or horizontal, or if possible, look at the angle from a different point of view which may help to view a line of the angle from a vertical or horizontal position.
Spend time moving on from the use of angle tools to estimate angles to estimating only with the two given lines. Pupils should look to develop a sense of different angle sizes in different orientations.
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).Lesson video
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Starter quiz
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6 Questions
Q1.
This is an example of an acute angle. Which of these is the definition of an acute angle?
Any angle that is less than 180°
Any angle that is more than 90°
Any angle that is exactly 90°
Q2.
Look at the hands on this clock face and the arrow. How does the angle created by the hands compare to a right angle?
Smaller than a right angle.
Equal to a right angle.
Q3.
Look at the hands on this clock face and the arrow. The angle formed is __________.
an acute angle.
a right angle.
an obtuse angle.
Q4.
This is a triangle. Look carefully at the vertices and the angles inside the shape. Complete the sentence. There are acute angles in the triangle.
Q5.
This is a hexagon. Look carefully at the vertices and the angles inside the shape. Complete the sentence. There are obtuse angles in the hexagon.
Q6.
Complete the sentence. This is an example of an angle.
Exit quiz
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6 Questions
Q1.
What type of angle is shown here?
Q2.
Which of these is the best estimate for the angle shown?
80°
170°
Q3.
Which of these is the best estimate for the angle shown?
1°
5°
40°
Q4.
This is a triangle. Which of these is a good estimate for the angle of the circled vertex?
20°
25°
75°
90°
Q5.
This is a hexagon. Which of these is a good estimate for the angle of the circled vertex?
75°
90°
145°
Q6.
This is a hexagon. Which of these is a good estimate for the angle of the circled vertex?
90°
175°
200°