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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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Share activities with pupils
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.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. You can estimate angles by comparing to a right angle of 90 degrees.
  2. Half a right angle is 45 degrees.
  3. One and a half right angles are 135 degrees.

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.

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.

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 (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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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?
An image in a quiz
Any angle that is less than 180°
Correct answer: Any angle that is less than 90°
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?
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Smaller than a right angle.
Equal to a right angle.
Correct answer: Greater than a right angle.
Q3.
Look at the hands on this clock face and the arrow. The angle formed is __________.
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an acute angle.
a right angle.
an obtuse angle.
Correct answer: a reflex 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.
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Correct Answer: 2
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.
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Correct Answer: 2
Q6.
Complete the sentence. This is an example of an angle.
An image in a quiz
Correct Answer: obtuse, obtuse angle

Exit quiz

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6 Questions

Q1.
What type of angle is shown here?
An image in a quiz
Correct Answer: acute, acute angle
Q2.
Which of these is the best estimate for the angle shown?
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80°
Correct answer: 120°
170°
Q3.
Which of these is the best estimate for the angle shown?
An image in a quiz
1°
5°
Correct answer: 25°
40°
Q4.
This is a triangle. Which of these is a good estimate for the angle of the circled vertex?
An image in a quiz
20°
25°
Correct answer: 45°
75°
90°
Q5.
This is a hexagon. Which of these is a good estimate for the angle of the circled vertex?
An image in a quiz
75°
90°
Correct answer: 110°
145°
Q6.
This is a hexagon. Which of these is a good estimate for the angle of the circled vertex?
An image in a quiz
90°
Correct answer: 140°
175°
200°