Year 4 - Maths
Know that the perimeter of a rectangle can be calculated by addition and multiplication
Perimeter
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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 pupil will learn perimeter as the distance around the edge of a 2D shape. They will learn perimeter is measured in units of length found by counting units and by calculating by adding the side lengths of a 2D shape.
Lesson Summary
You will learn to calculate the perimeter of a rectangle using addition and multiplication.
Key Notes
- To calculate the perimeter of a rectangle you can double the lengths of the shorter and longer sides and add the values.
- To calculate the perimeter of a rectangle you can add one long and one short side and double the total.
- Mental and written methods can be used to calculate the perimeter of a 2D shape.
Vocabulary To Learn
- Perimeter: The distance around a two-dimensional shape.
- Double: Have two of something.
Common Mistakes To Avoid
- Pupils may not realise that, even when one of the long side and short side lengths is missing in a rectangle, they still have enough information as these are the same as the given lengths.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
To calculate the perimeter of a rectangle you can double the lengths of the shorter and longer sides and add the values. To calculate the perimeter of a rectangle you can add one long and one short side and double the total.
2. Use this key word in a maths sentence and explain it clearly. 'Perimeter'
The distance around a two-dimensional shape. 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 not realise that, even when one of the long side and short side lengths is missing in a rectangle, they still have enough information as these are the same as the given lengths. Correction: Counters are encouraged in this unit. It may be that some pupils still need the missing side lengths written on counters, but as with all scaffolding, this should only be temporary. Ask them - do you need this counter? Do you already know the number?
More Lessons In This Unit
- Calculate the side length of a regular polygon by division where the perimeter is known Study Guide
- Know that a regular polygon has sides that are the same length and angles that are the same size Study Guide
- Know that perimeter can be calculated by adding together the side lengths of a 2D shape Study Guide
- Know that perimeter is measured in units of length and can be found by counting or measuring units Study Guide
- Know that the perimeter is the distance around a 2D shape Study Guide
- Know that unknown side lengths can be calculated from the perimeter and known side lengths Study Guide
- Solve problems involving the perimeter and side lengths of polygons Study Guide
- Understand that different shapes can have the same perimeter Study Guide
- Understand that the perimeter of a regular polygon can be calculated by multiplication Study Guide
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