Practical skills
This lesson builds density practical method, calculation and uncertainty for GCSE Physics.
Use the core lesson first, then match the exam-board guidance to your school route. Many pupils meet this content through Combined Science as well as Separate Physics.
What you will learn
Exam-board fit
Exact paper labels and specification-point numbering vary by board and cohort, so match this lesson to your school route before using past-paper questions.
Density practical data supplied on this page
Use the cuboid, stone and liquid examples to practise choosing the right volume method before calculating density.
Clear explanation
Density tells you how much mass there is in each unit volume. The equation is density = mass ÷ volume.
For a regular solid, measure length, width and height, then calculate volume. For an irregular solid, use water displacement and read the change in water volume.
For a liquid, measure the mass of an empty container, then the mass of the container with liquid, and subtract to find the liquid mass.
Key diagram
Worked examples
Density of a cuboid
A cuboid has mass 240 g and volume 80 cm3.
density = mass ÷ volume
density = 240 ÷ 80
Quick checks
Choose an answer, then check your thinking.
1. Which equation is used for density?
2. How can you find the volume of an irregular stone?
Practice questions
Question 1
A solid has mass 180 g and volume 60 cm3. Calculate density.
Reveal answer and marking guidance
Answer: 3 g/cm3.
Marking: Credit density = mass ÷ volume and 180 ÷ 60 = 3 g/cm3.
Question 2
A measuring cylinder reads 40 cm3 before a stone is added and 68 cm3 after. What is the stone volume?
Reveal answer and marking guidance
Answer: 28 cm3.
Marking: Credit 68 - 40 = 28 cm3.
Question 3
Why should the balance be zeroed before measuring mass?
Reveal answer and marking guidance
Answer: To avoid a zero error affecting the mass reading.
Marking: Credit reducing systematic error.
Question 4
How do you find the mass of a liquid using a container?
Reveal answer and marking guidance
Answer: Subtract the empty container mass from the container plus liquid mass.
Marking: Credit mass difference method.
Exam practice ladder
Answers and marking guidance
The exact practice answers are hidden under each question so you can try first. For this lesson, marks come from using the correct physics model, choosing the right equation where needed, keeping units with values, and explaining changes with precise words such as transfer, resultant force, acceleration, evidence and uncertainty.
Common mistakes
- Using volume divided by mass.
- Forgetting to subtract the empty container mass.
- Reading the measuring cylinder from above or below the meniscus.
- Mixing cm3 and m3 without converting.
Exam-board guidance
All supported routes assess the core physics idea, but they may group topics, practicals and paper wording differently.
AQA GCSE Physics
AQA GCSE Physics: use this lesson for density practical method, calculation and uncertainty, then check whether your class is taking Separate Physics or Combined Science.
OCR GCSE Physics
OCR GCSE Physics: the core physics idea is shared, but Gateway and Twenty First Century may organise questions differently.
Pearson Edexcel GCSE Physics
Pearson Edexcel GCSE Physics: practise the concept, the equation use and the practical language because questions often connect them.
Eduqas GCSE Physics
Eduqas GCSE Physics: learn the core explanation and practise applying it to unfamiliar contexts, data and practical questions.
WJEC Wales
WJEC Wales: check whether your class is using the current GCSE Physics route or a newer science route, then use this lesson for the shared physics idea.
CCEA GCSE Physics
CCEA GCSE Physics: connect the idea to your unit and remember that practical skills are assessed directly.
Extension challenge
Compare two methods for measuring the volume of an irregular solid and explain which has lower uncertainty.
Reveal answer
Example answer: A strong extension response names the physics model, uses accurate units and explains why the evidence supports the conclusion.
Next lesson
Next, continue with Terminal Velocity and Free-Body Diagrams.