Year 8 - Maths
Circumference of a circle
Perimeter, area and volume
Study Hub
Study Guides
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 use the relationship C=πd to calculate unknown lengths in contexts involving the circumference of circles.
Key Notes
- The formula can be used to find the circumference when you know the diameter.
- The formula can be used to find the circumference when you know the radius.
- The formula can be used to find the radius or diameter when you know the circumference.
- These answers will be rounded to an appropriate degree of accuracy.
- For the answer to be exact it needs to be left in terms of π.
Vocabulary To Learn
- Circumference: The circumference of a circle is the perimeter of the circle.
- Radius: The radius of a circle is any line segment that joins the centre of a circle to its edge.
- Diameter: The diameter of a circle is any line segment that starts and ends on the edge of the circle and passes through the centre.
Common Mistakes To Avoid
- When writing answers in terms of π, pupils may think that π is the units.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The formula can be used to find the circumference when you know the diameter. The formula can be used to find the circumference when you know the radius.
2. Use this key word in a maths sentence and explain it clearly. 'Circumference'
The circumference of a circle is the perimeter of the circle. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When writing answers in terms of π, pupils may think that π is the units. Correction: π is a constant and makes up part of the numerical component of the answer. Units (such as square metres) still need to be stated.
More Lessons In This Unit
- Area of a circle Study Guide
- Area of composite shapes Study Guide
- Checking understanding of area Study Guide
- Checking understanding of perimeter 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.