Year 4 - Maths
Explore symmetry by joining two identical shapes
Properties of 2D and 3D shapes and symmetry
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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 complete and compose symmetrical shapes from two congruent shapes and investigate lines of symmetry in 2D shapes.
Lesson Summary
You will learn to compose symmetrical shapes from two identical shapes.
Key Notes
- A shape is symmetrical when one half is a reflection of the other half.
- When you fold a shape on a line of symmetry, the two halves will match exactly.
- You can join two identical shapes together to create a new shape.
- When you join two identical shapes, sometimes the new shape will be symmetrical.
- When you join two identical shapes, sometimes the new shape will have no lines of symmetry.
Vocabulary To Learn
- Symmetrical: When a shape, pattern or image has two halves that match exactly when folded, it can be described as symmetrical.
- Line of symmetry: If you were to fold a shape at its line of symmetry, both halves would match exactly.
- Identical: Two shapes that are exactly the same can be described as identical.
Common Mistakes To Avoid
- Some children will think that a parallelogram is symmetrical because it can be divided in half.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
A shape is symmetrical when one half is a reflection of the other half. When you fold a shape on a line of symmetry, the two halves will match exactly.
2. Use this key word in a maths sentence and explain it clearly. 'Symmetrical'
When a shape, pattern or image has two halves that match exactly when folded, it can be described as symmetrical. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Some children will think that a parallelogram is symmetrical because it can be divided in half. Correction: Demonstrate with folding and by using mirrors why dividing a parallelogram in half does not result in a line of symmetry. Allow children to explore this concept with cut-outs of different parallelograms.
More Lessons In This Unit
- Complete a symmetrical pattern Study Guide
- Diagonal lines of symmetry Study Guide
- Explore, sort and classify triangles Study Guide
- Find lines of symmetry in 2D shapes Study Guide
- Identify different types of triangle Study Guide
- Investigate lines of symmetry in 2D shapes by folding Study Guide
- Investigate symmetry and symmetrical patterns Study Guide
- Reflect polygons in a line of symmetry Study Guide
- Reflect polygons that are dissected by the line of symmetry Study Guide
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