Year 8 - Maths
Checking understanding of perimeter
Perimeter, area and volume
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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 extend their knowledge of shapes by exploring the properties of circles and composite shapes before developing understanding of 3-D shapes including surface area and volume.
Lesson Summary
You will learn to find the perimeter of many polygons or compound shapes.
Key Notes
- The perimeter of any polygon can be found by summing the sides.
- The perimeter of shapes made from polygons can be found.
- Some methods for finding perimeters are more efficient than others.
- Missing lengths can be found when the perimeter is known.
Vocabulary To Learn
- perimeter: the distance around a 2D shape
- polygon: flat (2D), closed figure made up of straight line segments
- compound/composite shape: a shape created using two or more basic shapes
Common Mistakes To Avoid
- Summing all of the given lengths and only the given lengths to find the perimeter.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The perimeter of any polygon can be found by summing the sides. The perimeter of shapes made from polygons can be found.
2. Use this key word in a maths sentence and explain it clearly. 'perimeter'
the distance around a 2D shape. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Summing all of the given lengths and only the given lengths to find the perimeter. Correction: With each example discuss which lengths are part of the perimeter, which lengths are not and whether any lengths are equal to others.
More Lessons In This Unit
- Area of a circle Study Guide
- Area of composite shapes Study Guide
- Checking understanding of area Study Guide
- Circumference of a circle Study Guide
- Finding a length in composite shapes Study Guide
- Multiplicative relationships in circles Study Guide
- Perimeter of composite shapes Study Guide
- Problem solving with perimeter, area and volume Study Guide
- Properties of prisms Study Guide
- Surface area of cuboids Study Guide
- Surface area of cylinders Study Guide
- Surface area of prisms Study Guide
- Using the formula for the area of a circle Study Guide
- Volume of cylinders Study Guide
- Volume of prisms Study Guide
Browse all guides in the Year 8 Maths guide library.