Year 5 - Maths
Measure the size of angles accurately using a protractor
Angles: compare, name, estimate and measure angles
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will compare the size of angles where there is a clear visual difference and use the terms acute, obtuse and reflex when describing the size of angles or amount of rotation with relation to right angles using a unit called degrees.
Lesson Summary
You will learn to measure the size of angles accurately using a protractor.
Key Notes
- A protractor is an angle measurer.
- Protractors have two scales from 0 to 180 degrees.
- Start from zero when reading the scale on a protractor.
- Line the protractor up with one of the lines forming the angle.
Vocabulary To Learn
- Angle: An angle is a measure of turn. It shows how far something has rotated. It is often displayed as the rotation between two line segments.
- Point: A point is an exact location. It has no size, only position.
- Vertex: A vertex is a point where two or more lines meet.
- Scale: A scale is a number line with equal divisions for equal values.
Common Mistakes To Avoid
- Pupils incorrectly place the protractor on the angle and therefore cannot measure the angle. Pupils use the incorrect scale to read the angle.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
A protractor is an angle measurer. Protractors have two scales from 0 to 180 degrees.
2. Use this key word in a maths sentence and explain it clearly. 'Angle'
An angle is a measure of turn. It shows how far something has rotated. It is often displayed as the rotation between two line segments. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils incorrectly place the protractor on the angle and therefore cannot measure the angle. Pupils use the incorrect scale to read the angle. Correction: Stress the importance of using the middle spot on the protractor to line this up with the vertex of the angle as well as placing one of the lines on a zero line, ensuring the remaining line crosses the scale of the protractor.
More Lessons In This Unit
- Angles in quadrilaterals Study Guide
- Angles in triangles Study Guide
- Describe rotations using the standard unit of degrees when compared to a right angle Study Guide
- Describe static angles using the standard unit of degrees when compared to a right angle Study Guide
- Draw angles accurately using a protractor Study Guide
- Estimate acute and obtuse angles using the standard unit of degrees Study Guide
- Know that the angles at a point sum to 360 degrees and use this to solve problems Study Guide
- Know that the angles in a full turn sum to 360 degrees and use this to solve problems Study Guide
- Know that the angles on a straight line sum to 180 degrees and use this to solve problems Study Guide
- Reasoning about angles in polygons Study Guide
- Review understanding and identification of right angles Study Guide
- Review understanding of angles as a measure of turn Study Guide
- Use the terms acute, obtuse and reflex when comparing angles to a right angle Study Guide
- Use the unit of degrees as a standard unit to measure angles Study Guide
Browse all guides in the Year 5 Maths guide library.