New
New
Year 5

Use the terms acute, obtuse and reflex when comparing angles to a right angle

I can use the terms acute, obtuse and reflex when comparing angles to a right angle.

New
New
Year 5

Use the terms acute, obtuse and reflex when comparing angles to a right angle

I can use the terms acute, obtuse and reflex when comparing angles to a right angle.

Lesson details

Key learning points

  1. Angles are marked with a curve between the lines which have been rotated
  2. Angles with a bigger turn are larger than those with a smaller turn
  3. Angles can be bigger than a right ange or smaller than a right angle

Common misconception

Angles must always be formed with one horizontal line. Angles must also have two straight lines that are exactly the same length.

Provide pupils with examples where acute, obtuse and reflex angles are shown in a wide range of orientations and where the length of the lines leading into the angles differ in size to support generalising the features of each angle type.

Keywords

  • Angle - An angle is a measure of turn. It shows how far something has rotated.

  • Right angle - A right angle is a square corner or a quarter turn.

  • Acute angle - An angle that is smaller than a right angle is an acute angle.

  • Obtuse angle - An angle that is greater than a right angle but smaller than a straight line is an obtuse angle.

  • Reflex angle - An angle that is greater than a straight line up to a full turn is a reflex angle.

Encourage children to make sense of the language used to label each type of angle. Relate this to everyday examples so that pupils can connect the terminology used more easily with examples of each angle.
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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6 Questions

Q1.
Look at the image. This shape has right angles.
An image in a quiz
Correct Answer: 2, two
Q2.
This shape has one pair of parallel sides. True or false?
An image in a quiz
Correct answer: True
False
Q3.
Complete the sentence. A parallelogram has vertices.
Correct Answer: 4, four
Q4.
Match the shape to its properties.
Correct Answer:square,A polygon with four equal sides and four right angles.

A polygon with four equal sides and four right angles.

Correct Answer:triangle ,A polygon with three sides and three vertices.

A polygon with three sides and three vertices.

Correct Answer:pentagon ,A polygon with five sides and five vertices.

A polygon with five sides and five vertices.

Q5.
The minute hand shows 4 o’clock. The minute hand moves a quarter turn clockwise. What time is shown?
An image in a quiz
Correct answer: Quarter past 4
Half past 4
Quarter to 5
5 o’clock
Q6.
Which of the angles shown is the smallest?
A
Correct answer: B
C

6 Questions

Q1.
Which type of angle is shown?
An image in a quiz
Acute
Right
Correct answer: Obtuse
Reflex
Q2.
Which type of angle is shown?
An image in a quiz
Correct answer: Acute
Right
Obtuse
Reflex
Q3.
Look at the hands on this clock face and the arrow. The angle formed is __________.
An image in a quiz
Acute
A right angle
Correct answer: Obtuse
Reflex
Q4.
Look at the hands on this clock face and the arrow. The angle formed is __________.
An image in a quiz
Acute
A right angle
Obtuse
Correct answer: Reflex
Q5.
This is a trapezium. Look carefully at the vertices and the angles inside the shape. Complete the sentence. There are acute angles in the trapezium.
An image in a quiz
Correct Answer: 2, two
Q6.
This is a trapezium. Look carefully at the vertices and the angles inside the shape. Which statement is correct?
An image in a quiz
The trapezium has four obtuse angles.
The trapezium has two right angles and two acute angles.
The trapezium has two right angles and two obtuse angles.
Correct answer: The trapezium has two right angles, one acute angle and one obtuse angle.