Year 3 - Maths
Investigate the shapes made when rectangles are cut on the diagonal
Right 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 rotate 2 lines around a fixed point to make different angles. They identify vertices and describe half, quarter and three-quarter turns in terms of right angles.
Lesson Summary
You will learn to describe the shapes made when rectangles are cut on the diagonal.
Key Notes
- An angle can be exactly a right angle.
- An angle can be less than or greater than a right angle.
- When you cut a square using two diagonal lines, you get four identical triangles.
- When you cut a rectangle that is not a square using two diagonal lines, you get two pairs of identical triangles.
Vocabulary To Learn
- Diagonal: A straight line connecting one vertex to another, but is not the side or edge.
Common Mistakes To Avoid
- Pupils may find it hard to recognise when an angle is greater than a right angle.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
An angle can be exactly a right angle. An angle can be less than or greater than a right angle.
2. Use this key word in a maths sentence and explain it clearly. 'Diagonal'
A straight line connecting one vertex to another, but is not the side or edge. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils may find it hard to recognise when an angle is greater than a right angle. Correction: You can model this by trying to move the obtuse angle (though pupils don't need to know the term yet) within a right angle checker. They should be able to see that it is too large to fit.
More Lessons In This Unit
- Identify and describe right angles Study Guide
- Identify properties of quadrilaterals Study Guide
- Identify properties of triangles Study Guide
- Investigate and draw other polygons with right angles Study Guide
- Join four right angles at a point using different right-angled polygons Study Guide
- Know that a rectangle is a four-sided polygon with four right angles Study Guide
- Know that a right angle describes a quarter turn Study Guide
- Know that a square is a rectangle in which the four sides are of equal length Study Guide
- Make different sized angles by rotating two lines around a fixed point Study Guide
Browse all guides in the Year 3 Maths guide library.