Year 6 - Maths
Reason about compound shapes using the relationship between side lengths and area and perimeter
Draw, compose and decompose shapes
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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 use knowledge of shape properties to draw, sketch and identify shapes.
Lesson Summary
You will learn to reason about compound shapes using the relationship between side lengths and area and perimeter.
Key Notes
- Area and perimeter are calculated from the side lengths of 2D shapes.
- Area and perimeter are measured in different units.
- Compound shapes can be decomposed and rearranged in different ways.
Vocabulary To Learn
- Compound: A compound shape is a shape created using two or more basic shapes.
- Dimension: A dimension is a measurement of length in one direction.
Common Mistakes To Avoid
- The numbers used as side lengths in this lesson are generally relatively low, and based around times tables. As a result, pupils might be tempted to guess / estimate the missing side lengths.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Area and perimeter are calculated from the side lengths of 2D shapes. Area and perimeter are measured in different units.
2. Use this key word in a maths sentence and explain it clearly. 'Compound'
A compound shape is a shape created using two or more basic shapes. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: The numbers used as side lengths in this lesson are generally relatively low, and based around times tables. As a result, pupils might be tempted to guess / estimate the missing side lengths. Correction: Remind pupils that the shapes are not to scale and encourage them to use subtraction skills instead - what is the difference between this known side length and this known side length?
More Lessons In This Unit
- 3D shapes can be composed from 2D nets Study Guide
- Any parallelogram can be decomposed and the parts rearranged to form a rectangular parallelogram Study Guide
- Reason about shapes using the relationship between side lengths and area and perimeter Study Guide
- Shapes with the same areas can have different perimeters and vice versa Study Guide
- The same 3D shapes can be composed from different 2D nets Study Guide
- Two congruent triangles can be arranged to compose a parallelogram Study Guide
- Use knowledge of shape properties to draw shapes accurately using rulers and protractors Study Guide
- Use knowledge of shape properties to sketch and identify shapes Study Guide
- When a 2D shape is decomposed and the parts rearranged, the areas remains the same Study Guide
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