Year 5 - Maths
Reasoning about angles in polygons
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 reason about the sum of the angles within different polygons.
Key Notes
- Angles describe and measure a turn or rotation.
- Protractors can be used to measure and draw angles.
- Use knowledge of right angles to estimate and compare angles.
Vocabulary To Learn
- Angle: An angle is a measure of turn.
- Sum: The sum is the result of adding two or more numbers.
- Vertex: A vertex is a point where two or more lines meet.
- Polygon: A polygon is a 2D shape made up of three or more straight lines.
Common Mistakes To Avoid
- Pupils think that composing larger polygons of smaller triangles that are not formed as a result of drawing a line from one vertex to another will help them to identify the sum of the angles.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Angles describe and measure a turn or rotation. Protractors can be used to measure and draw angles.
2. Use this key word in a maths sentence and explain it clearly. 'Angle'
An angle is a measure of turn. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils think that composing larger polygons of smaller triangles that are not formed as a result of drawing a line from one vertex to another will help them to identify the sum of the angles. Correction: Highlight how the formation of triangles within a polygon must be from vertex to vertex and demonstrate how the angles of each triangle where they meet sum to the internal angle of the polygon.
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
- Measure the size of angles accurately using a protractor 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
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